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Gladstone RJ. and Wakeley C. The Pineal Organ. (1940) Bailliere, Tindall & Cox, London. PDF

   The Pineal Organ (1940): 1 Introduction | 2 Historical Sketch | 3 Types of Vertebrate and Invertebrate Eyes | Eyes of Invertebrates: 4 Coelenterates | 5 Flat worms | 6 Round worms | 7 Rotifers | 8 Molluscoida | 9 Echinoderms | 10 Annulata | 11 Arthropods | 12 Molluscs | 13 Eyes of Types which are intermediate between Vertebrates and Invertebrates | 14 Hemichorda | 15 Urochorda | 16 Cephalochorda | The Pineal System of Vertebrates: 17 Cyclostomes | 18 Fishes | 19 Amphibians | 20 Reptiles | 21 Birds | 22 Mammals | 23 Geological Evidence of Median Eyes in Vertebrates and Invertebrates | 24 Relation of the Median to the Lateral Eyes | The Human Pineal Organ : 25 Development and Histogenesis | 26 Structure of the Adult Organ | 27 Position and Anatomical Relations of the Adult Pineal Organ | 28 Function of the Pineal Body | 29 Pathology of Pineal Tumours | 30 Symptomatology and Diagnosis of Pineal Tumours | 31 Treatment, including the Surgical Approach to the Pineal Organ, and its Removal: Operative Technique | 32 Clinical Cases | 33 General Conclusions | Glossary | Bibliography
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The Pineal Organ

Chapter 32 Clinical Cases

The following clinical cases have come under observation and treatment since 1919.

Case 1. — Elsa B., aged 26, was admitted to hospital under the late Sir David Ferrier, in May, 1919, complaining of headache and vomiting. Up to a year prior to admission the patient was a cheerful individual who was employed in a laundry, and was very keen on tennis. Gradually she lost interest in her work and gave up all games. For a month previous to her admission to hospital she had attacks of vomiting, and was unsteady while walking.

On Examination. — The patient appeared rather depressed, but was quite keen to cooperate in the hope that something could be done to relieve her symptoms. She walked with a staggering gait, but there did not seem to be any tendency to fall to either side. She had a good sense of smell. The visual fields were complete. Bilateral papilloedema was present, more marked on the right side — right, four diopters ; left, three diopters. The pupils were dilated and did not react to light or accommodation. There was loss of conjugate upward movement of the eyes. There was weakness of the right Vlth nerve and bilateral nerve deafness. The other cranial nerves appeared normal. There was a fine lateral nystagmus to the right. Ataxia was marked and Romberg's sign was positive. The diagnosis of a pontine or pineal tumour was made, and a subtentorial decompression advised.

Operation. — On 15th May, 1919, a large subtentorial decompression was performed under ether anaesthesia ; there was marked increase of the intracranial pressure, but no tumour was discovered. The wound was closed without drainage. Healing was sound and the stitches were removed after ten days. The patient rapidly improved after the operation, the vomiting stopped completely, and the papilloedema subsided. However, a month after the operation the decompression area began to bulge (Fig. 301), and the papilloedema returned. The patient began to go downhill and died two months after her operation.

An autopsy was performed and the brain removed entire and hardened. No obvious tumour could be seen. After the hardening process was complete, several sections were made through the entire brain, and a pineal tumour was discovered.

Pathology. — The tumour was situated between the splenium of the corpus

callosum and the quadrigeminal plate of the midbrain, both these parts being

invaded by an ingrowth of the tumour (Fig. 302). Its maximum transverse

diameter in the section examined was 17 mm. and its vertical measurement

15 mm. There was no definite capsule, the growth being limited by the tissues with which it came into contact. Thus it was covered laterally by vascular

Fig. 301. — Photograph of Case i, showing Bulging through a Sub-tentorial


pia mater, and where it was invading nerve-tissue this was pushed aside and compressed, the original covering having been either partially or completely destroyed. The aqueductus cerebri had been flattened by pressure, its roof

Fig. 302. — Case i. Brain after Removal, show Position of Pineal Tumour.

being almost in contact with the floor except in the centre, where in the position of the median groove in its floor the section showed a triangular space with the apex directed downwards. The single layer of cubical epithelium which lines the duct was retained on the right side, but had disappeared for the most part on the left side, where it was replaced by an ingrowth of vascular glial tissue. In the nerve-tissue of the splenium and quadrigeminal plate which surrounded the growth there was a considerable increase in the number and size of the blood-vessels. Many of these contained thrombi, in which there was a relatively very high proportion of lymphocytes as compared with red blood-corpuscles. The walls of the vessels were thickened, and there was a considerable nuclear proliferation in surrounding glial tissue.

The surface of the tumour was very irregular and in places lobulated. The central parts were broken down, an irregular cavity being present in the lower part of the section, with spaces running out from the main cavity into the central axes of the lobules, where the destruction of tissue was less complete. The

Fig. 303. — Case i. Small Cyst in Base of Tumour containing Choroidal Villi. Ca. : calcareous body. C.V. : choroidal villus,

central axes of the lobules showed a canal which was in some places lined by flattened epithelial cells, external to which was a layer of condensed glial tissue continuous with that of the tumour. These spaces were for the most part empty, but occasionally contained a small amount of cell debris or degenerated blood-corpuscles. They probably represent remnants of the lumen of the original pineal outgrowth which had become cystic.

The tumour cells were loosely arranged in a lobular manner around these cystic spaces, the lobules being separated by vascular ingrowths from the surface. Two principal types of cell were present : the majority had spherical nuclei, deeply stained with hematoxylin, and surrounded by a small amount of feebly stained cytoplasm. Among these were larger cells with a feebly stained round or oval nucleus. They appeared to belong to the supporting glial tissue, which in some places formed a trabecular network similar to that seen in the normal gland. No mitotic figures appeared to be present, though in some parts the cells were of small size and closely packed together, suggesting an active proliferation. In the upper part of the tumour there were extensive areas of necrosed tissue showing an irregular fibrinous network containing degenerated red blood-corpuscles and leucocytes, which were intersected by strands of degenerated glial tissue.

A small cyst lined by ependyma and containing choroidal villi was present at the base of one of the lobules in the lower part of the tumour (Fig. 303).

This was probably a remnant of the dorsal diverticulum, which was present during foetal life and projects backwards over the pineal body from the posterior part of the roof of the third ventricle. This figure should be compared with Fig. 304, which represents a small cyst, lined by cylindrical ependymal cells, found in the substance of the epiphysis of an ox.

Fig. 304. -Small Cyst, lined by Cylindrical and Irregularly Shaped Ependymal Cells, in an Epiphysis of Bos taurus.

Some of the ependymal cells send processes outward towards the periphery. (After Dimitrowa, 1901.)

Case 2. — Harry P., aged 12, was admitted to hospital in October, 1923, with a history of constant headaches for nearly two years. He had been fitted with various glasses without any benefit. Four months before admission he had his tonsils and adenoids removed, as it was thought that this treatment might alleviate the headaches.

On Examination. — The patient was thin, and inclined to be irritable. There was no sign of pubertas praecox. The pupils reacted sluggishly to light and accommodation, and there was bilateral papilloedema of 4-5 diopters in each eye. The visual fields were normal. There was complete paresis of upward gaze and some weakness of the right Vlth nerve. The hearing on the right side was somewhat diminished. The other cranial nerves were normal. There was a slight lateral nystagmus to the right. The gait was somewhat ataxic and Romberg's sign was positive. There was very slight weakness of the right arm. All the deep reflexes were normal.

Radiographs revealed a calcified pineal body and some opening up of the sutures of the skull. After the boy had been in hospital for a week attacks of vomiting and sweating commenced, and it was thought that the condition might possibly be due to a tuberculoma. This diagnosis was supported by the fact that although the boy had a good appetite, he put on no weight and remained exceedingly thin. However, owing to the very definite paresis of upward gaze, it was decided that the more probable diagnosis was that of pinealoma.

Operation. — Under rectal ether and local anaesthesia a large osteoplastic flap was turned down over the right parieto-occipital region. The lateral ventricle was tapped, but owing to the poor condition of the patient no further exploration was carried out. The patient never really rallied, and died three days later.

At autopsy the pathologist unfortunately cut into the brain, and exposed a large but somewhat fragmentary vascular pineal tumour. Microscopically there was a definite mosaic arrangement of the cells, with one or two giant cells surrounded by a definite layer of small cells. It was unfortunate that the brain was not hardened before it was sectioned.

Case 3. — Hilda H., aged 25, was admitted to hospital on 30th October, 1930, complaining of headaches, sickness, and occasional attacks of double vision. The headaches were not continuous, but occurred spasmodically, the patient being quite free from them for several weeks at a time. The headaches first commenced about two years previously. A month before admission to hospital she became unsteady in her gait and could not see to mend her clothes. She was seen as an out-patient, and was found to have bilateral papilledema, and admission was recommended.

On Examination. — The patient was found to be well-nourished and quite cheerful and very keen to get well in order that she could go back to her work.

There was bilateral papilledema, four diopters of swelling in the right eye, and three diopters in the left. The pupils reacted sluggishly to light and accommodation. The visual fields were full. There was weakness of both Vlth cranial nerves. There was limitation of upward gaze, which increased while under observation in hospital. An X-ray examination showed some increase in the meningeal grooves in the skull, which was significant of increased intracranial pressure. There was no sign of calcification of the pineal gland. There was some ataxia on walking, but this on the whole was slight. There was a fine lateral nystagmus to the right, and slight deafness in the right ear. Rombergism was present. The deep reflexes were slightly increased on the right side of the body. There were no other neurological symptoms. The diagnosis of tumour of the pineal gland was made, and a supratentorial approach was advised.

Operation. — On 21st November, 1930, under intratracheal gas and oxygen anaesthesia combined with local infiltration, a large occipito-parietal osteoplastic flap was turned down on the right side. The dura mater was very tense, and to relieve the intracranial pressure the right lateral ventricle was tapped. The dura mater was incised and the cerebral hemisphere was carefully retracted ; several cerebral veins required to be secured by silver clips, as they entered the superior longitudinal sinus. On exposing the falx cerebri, a little more retraction brought the corpus callosum into view. Two silver clips were placed on the inferior longitudinal sinus and the falx was divided between them. The corpus callosum was then divided longitudinally, and a large tumour of the pineal gland was exposed. An attempt to remove this with the diathermy knife failed owing to excessive bleeding from the great vein of Galen and its tributaries. When the bleeding was more or less under control the condition of the patient was so very poor that the osteoplastic flap was replaced and the scalp wound closed. A blood transfusion of 400 c.c. of citrated blood was given immediately the patient returned to the ward. The condition of the patient rapidly improved and next day she was talking quite happily. There was wellmarked lateral nystagmus to the left and right.

Thirty-six hours after the operation the patient became drowsy and then unconscious, with a pulse-rate of 50. The upper part of the scalp wound was opened, the bone flap removed, and the lateral ventricle tapped. Some 40C.C of cerebrospinal fluid were withdrawn. The patient rapidly improved after this, but by the tenth day after operation, when the stitches were removed, there was considerable bulging of the scalp in the region of the wound ; 200 c.c. of a 15 per cent, sodium chloride solution were given intravenously. This worked like a charm, and the bulge completely disappeared for four days, when it became more tense again. As a further operation for the complete

Fig. 305. — Case 3.

Showing Bulging of Decompression Area in the Right Occipitoparietal Region.

removal of the tumour was refused by the patient, it was decided to give a course of X-ray treatments. Four treatments were given at two- weekly intervals, the applications being given over the decompressed area. This kept the patient quite fit, the papilloedema subsided, and the patient was able to go home.

On re-admisson. — She was readmitted in May, 193 1, with bulging of the decompression area and an increase in the papilloedema (Fig. 305). Operation was again refused and a further course of X-ray treatment was given. The patient was discharged in June, 193 1, in an improved condition ; the papilloedema was subsiding again and the cerebral hernia was less. She died quite suddenly in August, 1 93 1, but no autopsy was obtainable.

Case 4. — Albert P., aged 23, was admitted to hospital under the care of Dr. Worster-Drought, on 9th October, 1931, complaining of headaches, drowsiness, dizziness, and a constant " vacant " feeling. He was quite well until three months ago, when he first complained of occipital headache, which had persisted ever since. Soon after the headaches began he became drowsy and had attacks of " vacancy," during which he would sit or stand motionless for as long as half an hour. He slept well and ate well. Apart from headaches he did not feel ill. He had noticed dimness of vision on occasions. He had had several attacks of giddiness, in one of which he fell downstairs. He had only vomited once prior to admission. He had grown fatter during the last three months.

On Examination. — The patient was found to be somewhat slow in his movements. He weighed 12 st. i lb. A considerable amount of subcutaneous fat was noticeable (Fig. 306).

Cranial nerves. — The pupils were equal, but reaction to light and accommodation was slow. The visual fields were normal to rough tests. Bilateral papilloedema was present ; five diopters in the right and four in the left. There was no nystagmus, and the ocular muscles were normal. Speech was slow, and ponderous, and the whole attitude was slow and heavy ; he never smiled, and the facial expression seemed lost.

Sensation to cotton-wool and pin-pricks was quite normal. The cold tube felt hot on the right side of the trunk from the acromion process to the midline nearly down to the umbilicus. All limb reflexes were normal. The gait was slow, but with no obvious defect. Co-ordination, finger-nose test, was poor. Rombergism was slight. The heart, lungs, etc., were normal, and the blood-pressure 100 85. An X-ray examination made on 16th October, 1931, showed that the sella turcica was enlarged and erodefl, and the pineal body calcified. Cushing's thermic reaction was negative. The blood-sugar curve was normal. The visual fields were constricted. The cerebrospinal fluid showed : total protein 0-03 per cent. ; globulin, no excess. The Wassermann reaction was negative.

First Operation. — Air ventriculography was carried out on 31st October, 1931, under local anaesthesia. A small trephine was made in the right parietal bone and a cannula passed into the ventricle ; 200 c.c. of ventricular fluid were withdrawn and 140 c.c. of air introduced (Fig. 307).

The ventricular fluid was clear and colourless, cells 1 per There were no red corpuscles. Total protein was 0-015 P er cent. There was no excess of globulin, and the Wasserman reaction was negative. The patient was very drowsy after the ventriculography.

Fig. 306. — Case 4. Photograph of Patient suffering from a Pineal Tumour.

The vacant expression in this patient is well marked.

Second Operation. — On 5th November, 1931, a right subtemporal decompression was carried out under local anaesthesia. Considerable intracranial pressure was found. The patient stood the operation well, but afterwards became more drowsy and gradually got weaker. He suddenly collapsed and died on 21st November, 193 1. He had been running a high temperature for three days. The wound had quite healed and was healthy.

Pathology. — A post-mortem examination was carried out by Dr. Carnegie Dickson. The body was that of a well-nourished, well-developed young adult male, with little of note externally except that the figure showed a tendency to the female type. There was marked general flattening of the convolutions, more especially of the left hemisphere, which appeared to be slightly larger

Fig. 307. — Case 4. Radiograph after Ventriculography, showing Dilated Lateral Ventricles and Area of Pineal Tumour just beneath the Corpus Callosum.

than the right. The larger surface veins were somewhat dilated and the Pacchionian bodies about the vertex were numerous and prominent. Over the central portion of the base, e.g. over the pons and the interpeduncular space and dilated infundibulum, there was some thickening of the pia arachnoid.

On horizontal section of the brain at the level of the upper surface of the corpus callosum, the lateral ventricles were found to be very considerably dilated, especially the left, and the section at this level passed through a pearly " epidermoid " or " cholesteatomatous " tumour to the left side of the middle line, just posterior to the central point of the hemisphere, and occupying roughly the normal position of the left optic thalamus, which was displaced by the tumour forwards and outwards. This tumour had evidently arisen from the pineal region, the tumour lying mostly to the left side of this, pushing downwards the corpora quadrigemina and lamina quadrigemina and compressing the subjacent aqueduct of Sylvius, thus producing the hydrocephalus. The body of the pineal gland was still present, about the size of a small cherry-stone, and apparently more or less independent of the tumour, which, however, was in contact with its upper and left surface. The central portion of the pineal was removed for section, and the remaining sides of the gland sewn together to preserve the continuity of the specimen. The tumour was about the size of a large walnut or small plum, and it reached and pushed downwards and backwards the upper and anterior part of the cerebellum.

On the right side of the brain, just external to the dilated posterior ventricular horn, there was considerable softening and haemorrhage due to the compression, and the cerebrospinal fluid had evidently ruptured outwards at this point during the removal of the specimen. The right optic thalamus showed considerable bulging into the dilated right lateral ventricle, suggesting the possibility that this also contained tumour, but on cutting into it, this was disproved and it was found to be due merely to pressure displacement by the tumour to the left side, pushing it towards the right and upwards. Sections of the tumour itself had a glistening, pearly white iridescence, suggestive of the presence of cholesterol. Horizontal sections at a lower level showed much the same appearance, with dilatation of the ventricles, including the third ventricle, thus producing the prominent infundibulum as seen from below.

Histological Examination — Sections from various parts of the pearly tumour showed it to be a typical epidermoid consisting of a series of cysts or tumours, showing a concentric laminated appearance due to the production from the periphery inwards of squamous epithelium The outer or formative layer in most of these cysts is much degenerated or has largely disappeared, i.e. is now more or less inactive. Where it persists it shows a tendency to the production of multinucleated plasmoidal squamous cells. Here and there, however, the formation of outward budding and the production of further small cysts at the periphery of the main mass persist. The central portions of the cysts consist of desquamated epithelial cells and debris, including cholesterol crystals.

Sections of the pineal itself show at some parts more or less normal pineal structure, but at others there is distinct proliferation, with the production of what may be considered a simple pinealoma, involving more especially the larger pineal cells, and with little or no proliferation of the so-called " small lymphocytelike " cells.

The adenomatous cells are somewhat loosely arranged, the stroma varying in amount and in some parts being scanty and containing numerous thinwalled blood-vessels.

Case 5. — George W., aged 32, came under observation in March, 1932, complaining of giddiness and some difficulty in walking. The patient was a bank clerk, and was able to do his work until February, 1932, when he had an attack of influenza which kept him in bed for three weeks. On getting out of bed he found he was very unsteady on his feet and could not stand alone. He was treated with tonics and massage, but did not improve.

On Examination. — When seen on ioth March, 1932, he appeared to be somewhat dull and listless. His pupils were dilated and reacted sluggishly to light. There was bilateral papilloedema, there being five diopters of swelling in the right eye and four in the left. Except for slight bilateral deafness, the other cranial nerves appeared normal. There was a slight lateral nystagmus to the right. Rombergism was marked, and the patient was quite ataxic. The deep reflexes were normal, and there was no impairment to sensation.

Lumbar puncture revealed a clear colourless cerebrospinal fluid under pressure ; there were no abnormal constituents. The day following the lumbar puncture the patient was incontinent three times, and there was a well-marked lateral nystagmus. Also for the first time there was limitation of upward gaze and a definite weakness of the right sixth cranial nerve. Both lower limbs became spastic two days later. Radiographs of the skull revealed a midline calcified pineal shadow. This case was looked upon as a typical pinealoma, and removal was advised.

Operation. — On 21st March, under avertin and local anaesthesia, a large

right occipito-parietal osteoplastic flap was turned down, the lateral ventricle tapped, and the dura mater opened. Bleeding was reduced to a minimum by the application of silver clips and the use of the diathermy knife. The falx was exposed and the inferior longitudinal sinus severed between the clips. The inferior border of the falx was divided to the extent of half an inch. The splenium of the corpus callosum was split with a curved diathermy knife and a large pineal tumour exposed. Large FlG „ 308.— Case 5. Actual Size vdns could be seen surroun di ng the of Pineal Tumour after Removal. .... . , °

tumour. An incision into the tumour

was made with the diathermy knife, and a definite capsule appeared to cover the tumour. With a curved dissector the tumour was shelled out of its capsule. The bleeding, which was not great, was controlled by the use of diathermy. The retracted cerebral hemisphere was replaced and covered by dura mater. A small piece of corrugated rubber tubing was inserted into the region of the tumour and brought out through the upper part of the wound. The bone flap itself was removed, as it was thought that as the capsule had been left behind it would be advisable to give a course of X-ray treatment later. The patient stood the operation very well.

The following day the right ventricle was tapped and 30 c.c. of blood-stained cerebrospinal fluid were withdrawn. The drainage tube was removed after forty-eight hours. The fifth day following operation lumbar puncture was performed — the fluid was under slight pressure and blood-stained. From this day recovery was uneventful, and the patient left hospital a month after the operation.

The tumour was about the size of a plum (Fig. 308) and was quite hard in consistency. Histologically the tumour was a typical pinealoma.

Subsequent History. — At the end of May, 1932, the patient was given a course of X-ray treatment ; he seemed very well, and was able to go back to his office in September, 1932 ; he was able to walk quite well. There was no papilledema, but still some lateral nystagmus to the right. The patient had a bad attack of influenza in December, 1932, which was followed by pneumonia which proved fatal in four days. Every effort was made to obtain an autopsy, but this was refused by the relatives.

Case 6. — Harry F., aged 27, was admitted to hospital on 5th February, r 935j complaining of headaches. The duration of the present headache was about three weeks, but he had had a similar bout of headaches one year previously. The headaches were mostly occipital, but sometimes were on top of the head, mostly on the right side. They lasted for a quarter of an hour, and were worse in the morning. On two occasions he had vomited in the last three weeks, and frequently was nauseated without vomiting. He had double vision for moderately distant objects, which was getting worse. Movement of the eyes was painful. He suffered from giddiness two or three times a week, mostly when standing. There was no tendency to fall to one side more than to the other. There was no deafness, no noises in the head, no loss of power in any part of the body, and no unconscious attacks. There was no difficulty in speech, but he experienced difficulty in swallowing. There was no urinary trouble. He sometimes had numbness at the back of the head, but did not suffer from pins-and-needles in the extremities.

There was no previous history of ear trouble or of trauma. The patient had fainted once five years ago, and had had Vincent's angina three years ago.

On Examination. — On examining the fundi on 12th February, 1935, the edge of the left disc was less distinct than that of the right. Papilloedema on the left side was in sharp contrast to a lesser amount on the right. The veins in both fundi were distinctly enlarged.

On 19th February a stereoscopic X-ray examination of the skull showed a small rounded shadow of calcified pineal, a linear shadow situated at a certain distance from the rounded shadow and quite close to the right temporal bone.

On 24th February examination of the fields showed no abnormality. The patient continued to complain of severe headaches, and diplopia was still present.

Operation. — Ventriculography was performed on 7th March. Both lateral ventricles were very dilated (Fig. 309). The patient was given avertin anaesthesia with gas, oxygen, and ether. A large flap was turned down over the right occipito-parietal region. The dura was quite tense, and the lateral ventricle was therefore tapped and some 80 c.c. of fluid withdrawn. The dura mater was then incised and the occipital pole of the brain was retracted outwards. The inferior border of the falx was now incised after having clipped the inferior sagittal sinus by means of silver clips. The splenium of the corpus callosum was pushed upwards by the underlying tumour ; the splenium was cut through with a knife and the tumour exposed. It was a vascular tumour and a portion was removed with punch forceps. It was considered impossible to remove the tumour owing to the great vascularity, and therefore the occipital pole of the brain was replaced and the dura held together by three interrupted sutures ; the bone flap was removed and the scalp united by a double row of interrupted sutures. The patient stood the operation very well, and after three weeks deep X-ray therapy was given through the defect in the skull made by removal of the bone flap.

The portion of tissue removed showed a typical pineal tumour, with plenty of large cells (Fig. 310).

Fig. 309. — Radiograph after Ventriculography, showing Dilated Lateral Ventricle.

Subsequent progress. — The patient was discharged from hospital two months later, but the stigmata of the pineal tumour, due to pressure on the corpora quadrigemina, still persisted.

The patient was admitted on 19th October, 1935, for a second course of deep X-ray therapy ; but this did not have a very beneficial effect, and the

Fig. 310. — Case 6. Histological Appearance of Pineal Tumour ( 32).

patient left hospital very little improved by this treatment. We were informed that he died a month afterwards at his home, no autopsy being obtained.

Case 7. — Herbert O., aged 23, was admitted to hospital on 4th March, 1935, complaining of double vision, which was first noticed some six weeks prior to admission. The onset had been gradual and seemed to follow a series of head aches. The patient blamed his left eye, as he said the false image was to the left of the real one. There had been no vomiting or blurring of vision. His speech was normal and memory good. He had had no fits.

On Examination. — The pupils were equal and reacted to light. There was absence of accommodation and of the upward and downward movements of the eyes. There was some slight ptosis of the left eye and some rotary nystagmus.

The cranial nerves appeared normal, with the exception of some weakness of the right Vllth, IXth, and Xllth. There was no sensory loss in the arms, but some slight intention tremor. Reflexes were increased in the arms, but were equal on the two sides. There was no weakness of the legs and no sensory loss. Knee and ankle-jerks were brisk and the plantars were extensor in type. There was bilateral papilloedema — right three diopters, left four diopters.

Fig. 311. — Case 7.

Photograph of Brain, showing Position of Pineal


Lumbar puncture gave a clear, colourless fluid with a pressure of 270 mm. Cells . . . . . . . . . . 10 per



Globulin test



Wassermann reaction

50 mg. per 100 c.c.

710 mg. per 100 c.c.


Within normal limits



A radiograph of the skull was normal except for some erosion of the posterior clinoid processes. The visual fields were normal.

The patient gradually became comatose and paralysed down the right side of the body, and died on 10th March, 1935, some six days after his admission, without any operation being contemplated.

Post- Mortem Examination. — At autopsy there was bilateral pulmonary collapse and enlargement of the heart. A very large tumour was found in the pineal region (Fig. 311). The photograph reveals the right half of the brain, showing a tumour 2-J- in. in diameter occupying almost the whole of the third ventricle, and extending forwards to the anterior commissure and below to the tuber cinereum. The tumour is infiltrating the superior corpora quadrigemina

Fig. 312. — Case 7. Low-power Picture of Histological Section of the

Pineal Tumour.

Fig. 313. — Case 7. High-power Picture of Histological Section of the

Pineal Tumour.

and the midbrain, extending to the interpeduncular space and the upper border of the pons. The point of origin of the tumour is not obvious, but from the mode of extension forwards into the third ventricle, and the direction of infiltra


tion downwards and forwards into the midbrain, it would seem that the tumour arose in the pineal gland, which is no longer distinguishable.

Histology. — Sections show a cellular tumour intersected by numerous capillaries. Some areas show the characteristic carrot-shaped cells arranged in circles, with their long, protoplasmic processes forming a fibrillary network in the centre (pseudo-rosettes) (Figs. 312, 313).

Case 8. — Henry B., aged 11, came under observation on 4th July, 1935, with a history of more or less constant headaches for two years. However, he was free for some weeks at a time. A week prior to admission he had repeated vomiting attacks which could not be stopped with any kind of treatment.

On Examination. — He was a well-built and well-nourished boy, and quite intelligent. He complained of double vision and inability to look upwards beyond the horizontal plane. The pupils did not react to light, but reacted quite well to accommodation. The visual fields were normal. There was slight weakness of the right external rectus. There was bilateral papilledema, more marked on the right side. The rest of the cranial nerves appeared normal. There was no loss of sensation in the body and the deep reflexes were normal. The cerebrospinal fluid was under tension, the manometric reading being 250. The fluid was clear and colourless and did not contain any abnormal constituents.

A radiograph of the skull (Fig. 314) revealed definite hammer markings owing to the increased intracranial pressure. The Wassermann reaction in the blood and cerebrospinal fluid was negative.

Four days after admission the patient was found to develop skew deviation of the eyes on looking at objects in front of him, and the double vision became constant.

Operation. — A ventricular puncture was performed and 100 c.c. of air injected into the lateral ventricle. Ventriculography revealed bilateral dilatation of the lateral ventricles. A diagnosis of pineal tumour was made, and a large osteoplastic flap was turned down over the right occipito-parietal region. The lateral ventricle was tapped and the occipital pole of the brain retracted outwards through the opening in the skull. The splenium was cut through revealing a large pineal tumour. A portion was removed for examination and the operation was terminated. The general condition of the patient improved somewhat and the wound healed well.

The microscopical examination revealed an undifferentiated form of pinealoma (Fig. 315).

Subsequent Progress. — After three weeks, deep X-ray therapy was given to the pineal region through three ports of entry, some nine treatments being given, and the boy was discharged on 1st September with very slight papillcedema and slight ataxia. On writing to the patient three months later from the followup department it was found that the boy had died in his sleep six weeks after leaving hospital and no post-mortem examination was held.

Case 9. — The specimen was obtained from a brain supplied to the Anatomy Department of King's College, London. No history of the case was available. A median longitudinal section of the brain showed a cyst which occupied the centre of the pineal body and compressed the quadrigeminal plate of the midbrain. The aqueductus cerebri was also compressed, but it was not completely obstructed, and there was no marked distension of the third or lateral ventricles (Fig. 316). The pia mater around the pineal body and neighbouring parts was considerably thickened.

The pineal cyst was removed for microscopical examination and serial longitudinal sagittal sections were cut and stained with hematoxylin and eosin and with picro-indigo-carmine.

These showed that the cavity of the cyst was formed by the breaking down of the central part of the pineal body. Its wall showed, in a modified form, the structure of the pineal gland (Fig. 317, A). There was a pseudo-epithelial stratum lining the cavity, the tissue immediately bounding the lumen being fibrillar and glial in nature. A middle zone, which formed the major part of

Fig. 314. — Case 8. Radiograph demonstrating hammer marking owing to the increased Intracranial Pressure due to a Pineal Tumour.

Fig. 315. — Case 8. Histological Picture showing Appearance of a Pineal Tumour ( 320).

the thickness of the cyst wall, showed typical parenchymatous pineal cells. These were of small size, but had relatively large nuclei ; they were imbedded in a loose glial network, which forms the supporting tissue throughout the whole thickness of the cyst wall.

There were some irregular plaques of calcareous deposit in the wall of the cyst, and corpora arenacea were abundant in the surrounding membranes, but were not present in the actual wall of the cyst.

Lying dorsal to the pineal body was a tubular diverticulum of the ependyma, which extended the whole length of the pineal body (Fig. 318). It opened into the third ventricle at the suprapineal recess, and contained groups of choroidal villi, which projected into its lumen (Fig. 317, B). This represents the persistent dorsal sac which is present in foetal life, and is formed as a tubular outgrowth from the roof of the posterior part of the third ventricle. It would probably have contributed to the secretion of the cerebrospinal fluid. Should its opening have become blocked, it might have given rise to a thin-walled cyst, which would have differed from the pineal cyst described above in having



Fig. 316. — Mesial Section of the Brain, showing Large Pineal Cyst lying between the splenium of the corpus callosum and the corpora Quadrigemina.




Fig. 317. — Case 9.

A — Section through the wall of the pineal cyst shown in Fig. 316. The lumen of the cyst lies below ; it is lined by a layer of condensed glial tissue, no ependymal epithelium being visible. The middle zone is formed of a degenerate tissue containing few parenchyma cells and showing numerous spaces. In the upper part of the section is the fibrous capsule.

Gli : glial tissue. Gl. st. : glial stratum. Lum. : lumen.

B — Portion of the wall of the dorsal diverticulum or suprapineal recess which lay above the pineal cyst. It shows sections of corpora arenacea and choroidal villi.

Ca. : corpus arenaceum. Cv. : choroidal villi.

a wall lined with ependymal epithelium, and most probably containing tufts of choroidal villi projecting into its lumen.

Pineal cysts lined by ependyma also occur, and vary in size from small microscopic cysts such as that shown in Fig. 304, in which the lining 30


epithelium is columnar in type, to larger cysts which are formed, as is indicated by septa projecting into the lumen, by the coalescence of adjacent smaller cysts. The lining membrane in the larger cysts, found in old

Fig. 318. — Case 9. Drawing of a Longitudinal Section of the Pineal Cyst, and the Suprapineal Recess above it, D.D. (R. J. G.)

A. : anterior end. P. cyst. : lumen of the pineal cyst.

C.V. : choroidal villi projecting into P. : posterior end. the lumen of the diverticulum.

subjects, is formed by flattened cells which have been described as " pseudo-ependymal." Whether these cells are responsible for the secretion of the fluid which fills the cyst or whether this fluid is derived from the vessels supplying the gland appears to be undetermined. 1

1 Further information on the development and nature of pineal cysts will be found in an article by Eugenia R. A. Cooper in the J. Anat., 67, 1932-3, p. 28.



The surgery of the pineal organ, although yet in its infancy, may be said to be advancing rapidly owing to the fact that neurological diagnosis becomes more established and more accurate each year.

The symptomatology tends to be more definite : there is usually a severe degree of raised intracranial pressure, associated with headache, vomiting, papilledema, epileptiform fits, and some cranial nerve paralysis. The eye signs are definite, with loss of pupillary reaction and failure of upward movement of the eyes.

Operations for the removal of pineal tumours have become standardized ; and even if the complete removal cannot be undertaken, a postoperative course of deep X-ray therapy will complete the cure, as the majority of pineal tumours are radio-sensitive.


1. The pineal system, including the parietal eye, its nerves, and the related cerebral ganglia is one of the most ancient sensory systems of the vertebrate phylum. The existence of a parietal sense-organ being plainly indicated in certain of the primitive ostracoderm fishes by the presence of a pineal plate, showing either a complete pineal canal or a pineal pit on the inner surface of the plate. The canal and plate are well seen in the examples of Anaspida and Cephalaspida, which are found in strata ranging from the lower Silurian 1 to the Devonian eras and in specimens of Pterichthys and Bothriolepis belonging to the Order Antiarchi, found in upper Devonian strata.

2. In these fishes there is definite evidence that the parietal eye coexisted with other sensory organs of the head, namely : the lateral eyes, the olfactory organs, and the vestibular or static organs ; and also that these had approximately the same relative positions to each other and the parietal foramen or pit that they have in the heads of living cyclostomes and other vertebrates.

3. The closure of the outer or superficial end of the parietal canal by a thin plate of bone in certain examples indicates that in these specimens

1 The Silurian Epoch has been estimated by Barrell to embrace a period from 390,000,000 to 460,000,000 years ago.



regression of the organ had already commenced, and that it had ceased to function as a visual organ.

4. In some palaeozoic fishes, e.g. Pholidosteus, Rhinosteus, and Titanichthys, bilateral pineal impressions are visible, either (a) on the dorsal or outer aspect of the pineal plate, or (b) on its inner or intracranial surface. Moreover, evidence of the bilateral nature of the pineal system is also present in existing species. Thus in some species in which two separate parietal eyes are present, e.g. Petromyzon or Geotria, each eye is connected by its own nerve with the habenular ganglion of the same side ; and when the two parietal organs differ in size there is a corresponding difference in size of the habenular ganglion and also of the fasciculus retroflexus of Meynert of the two sides.

5. In those animals in which there is normally only one parietal sense-organ or an unpaired epiphysis, the normal connections of the basal part of the stalk of the parietal organ or of the epiphysis with the right and left habenular ganglia and posterior commissure are bilateral. Moreover, the occasional occurrence of accessory parietal sense-organs and indications of coalescence of two retinal placodes, or of two lenses in a single eye, may also be regarded as evidence pointing to a primary bilateral origin of the system. Bifurcation of a single pineal stalk into two terminal vesicles has also been observed as a variation in different classes of vertebrates, more particularly in fishes (Cattie) ; in amphibia (Cameron) ; in reptiles (Spencer, Klinckowstroem) ; in birds, e.g. Emys europea (Nowikoff ) ; and among mammals several instances in human embryos.

6. The development of two separate pineal diverticula, in the median plane and in the interval between the habenular commissure and the posterior commissure, seems to be a rare occurrence, although two terminal vesicles which have arisen from a common stalk may lie one behind the other. If one parietal vesicle only is developed and it is later cut off from its stalk of origin, the latter is usually displaced backwards so that the epiphysis lies behind the parietal eye. Apart from the paraphysis, which originates anterior to the velum transversum, diverticula arising from the roof of the third ventricle in front of the habenular commissure are developed from the dorsal sac or postvelar arch, and give rise to the suprapineal recess or are an outgrowth from the choroid plexus. Neither the paraphysis nor diverticula originating from the postvelar arch are epiphyseal in nature.

7. The parietal eye, which seems to have attained its maximum development in certain extinct amphibia, reptiles, and mammal-like reptiles, and the epiphysis or pineal body usually show signs of regression in specimens of mature living species. The most important of these


indications are : (1) the frequent absence or disappearance during the later stages of development of the nerve or nerves connecting the parietal eye or epiphysis with the central nervous system ; (2) excessive development of pigment in or around the retinal cells, or development of pigment in the lens or cornea ; (3) degeneration of the retinal epithelium of the parietal organ ; in the epiphysis of anamniota degeneration of the lining epithelium of the pineal stalk ; or in the pineal organ of adult birds, degeneration of the epithelium lining the follicles, accompanied in some cases by obliteration of the lumen of the follicles ; and in the pineal organ of adult mammals frequent degeneration of the parenchyma cells. The degree of degeneration of the parenchyma cells in adult mammals varies both in different individuals and in different parts of the organ in the same individual. In the latter case it is common to find areas in which the parenchyma cells have disappeared altogether and been replaced by neuroglial plaques or bands. These often break down in the centre to form cysts, and deposits of calcareous salts are frequently seen in the walls of the cysts or in the trabecular or capsule. See Figs. 221, A, B, C, 2 %5> 317? and 318.

8. In addition to the evidence in some extinct and living vertebrates of a single pair of pineal organs which are united, either partially in the stem of a Y-shaped organ bearing two terminal vesicles, or completely fusion having taken place throughout the whole length of the stalk which terminates in a single composite vesicle, there are indications, according to certain authors, of the existence of two pairs of parietal organs arranged serially, one pair lying in front of the other. Thus in the Palaeozoic fish Bothriolepis (Fig. 319), Patten describes, in addition to the median eye tubercle situated on the pineal plate between the two orbital cavities, a pair of bilateral impressions which are visible only on the internal aspect, and are present on the deep surface of the post-orbital plate (Fig. 320). These he believed lodged a pair of posterior median or parietal eyes. The three impressions or pits form a triangular group disposed in a similar manner to the median eyes of many invertebrates, and, more particularly, the triplacodal entomostracan eye which is found in certain Branchiopods, e.g. Apus and Branchipus (Figs. 248, 250), and in the " carp louse " Argulus foliaceus, which is typical of many other crustaceans. Another interpretation of the meaning of these two impressions is given on p. 472 by Stensio, who suggests that they are produced by the attachment of paired muscles of the lateral eyes. The existence and exact position of two pairs of retinal placodes which will give rise to the median eyes of vertebrates and which lie one in front of the other on each side of the open medullary plate, has not, we believe, been definitely established, nor is there agreement with respect to their exact position



__^ „-n h op

~-~-p orb pi.

relative to the pair of placodes which give origin to the lateral eyes. Thus, Patten assumes that two pairs of retinal placodes which become incorporated in the roof of the third ventricle and give rise to the parietal eyes of vertebrates lie in front of those for the lateral eyes in a position which he describes as typical, in the development of Arachnids (Figs. 257, 258, 259), whereas Locy in his account of two pairs of

p pi , n h " accessor y " or pineal eyes in

Acanthias, figures these as lying behind the placodal pits, which will develop into the optic vesicles of the lateral eyes (Fig. 143). Moreover, the intermediate stages between the first appearance of the two pairs of rudiments for the accessory eyes and the outgrowth of the pineal diverticulum in the later stages do not appear to have been definitely established by Locy. The appearance, however, of symmetically arranged sensory placodes or pigment spots formed in series around the margin of the medullary plate (Figs. 257, 258, 259), or head region (Fig. 19) in invertebrates suggests the possibility that one pair of a series of simple eyes being more favourably placed for the reception of visual impressions than the others — e.g. at the

Fig. 319. — Dorsal Aspect of Bothriolepis canadensis, showing the nasohypophyseal Opening, Lateral Orbits, Pineal and Postorbital Plate, and the Cephalic Appendages WHICH HAVE RECENTLY BEEN SHOWN TO

be True Pectoral Fins. (After Patten.)

n.h. op. : naso-hypophyseal opening.

orb. : orbital cavity.

p.f. : pectoral fin.

p. orb. pi. : postorbital plate.

p. pi. : pineal plate.

antero-lateral margins of the head on each side — becomes more highly evolved than those in front of or behind this pair The more favourably situated pair, it may be assumed, gains the ascendancy over the others and becomes the principal pair, whereas the less favourably situated ocelli retain their primitive simple character and tend to degenerate. If this is the case, and if as is commonly believed both the lateral and median eyes of vertebrates have been evolved from the simple eyes of a lowly organized type of invertebrate, the discrepancy which exists with regard to the position of the



median or accessory placodes relative to the optic pits for the lateral eyes in vertebrates may be readily explained.

The presence of the two impressions on the deep aspect of the posteromedian plate of Bothriolepis described by Patten has recently (1929-1930) been confirmed by Stensio, who gives an illustration (Fig. 321) of the same two pits in Aster olepis, an allied genus. He suggests that the pits are produced by the attachment of one or several of the recti muscles of


P^W J><>V P ek

v pp

Fig. 320. — Dorsal Aspect of the Ocular and Olfactory Plates of Bothriolepis ENLARGED. (AFTER PATTEN.)

A part of the olfactory and rostral plates has been removed on the left in order to expose the deeper-lying sclerotic plates. Between the lateral eyes is the quadrangular parietal plate, nearly perforated by a deep conical pit opening inward and covered externally by a thin, lens-like tubercle, beneath which was the parietal eye. On the deep aspect of the post-orbital (post median) plate are two similar pits, which Patten believed were occupied by a pair of posterior parietal eyes.

a.s. pi. : anterior sclerotic plate. le. : lateral ethmoid. Is. pi. : lateral sclerotic plate. me. : mesethmoid.

0. : corneal opening.

01. : site of primitive olfactory organ. p.e.t. : parietal eye tubercle.

po. pi. : postorbital plate.

p.p. : position of paired pits on inner

aspect of po. pi. p.s. pi. : posterior sclerotic plate. r. : rostrum. rs. : shelf plate on inner surface of


the lateral eye on each side ; a supposition which appears much more probable than Patten's hypothesis ; more especially since the investigations of Stensio and others into the general anatomy of these fishes have definitely proved that the cephalic appendages of Bothriolepis, Asterolepis ornata, and allied genera — which were at one time thought to closely resemble the cephalic appendages of the Merostomata, e.g. Eurypterus — are true pectoral fins, consisting of two segments, each of which contains inside the dermal bony exoskeleton, an axial cartilaginous endoskeleton, which in Bothriolepis was provided with a perichondral layer



of lime-bearing tissue, intermediate between true bone and calcified cartilage. The endoskeleton in the specimen described did not participate either in the axial articulation or in the articulation between the two segments of the fin, since both these articulations were formed solely by the dermal bones. In the proximal articulation the inner ends of the dermal bones embraced the neck, of the processus brachialis of the anterior ventro-lateral plate ; the opening in the dermal bones of the appendage which surrounded the process is called the axial foramen, and besides enclosing the head or condyle of the processus brachialis transmitted vessels and nerves to the appendage. The intermediate position in a direct line of descent between fishes and the invertebrate Merostomata, which was claimed for the Antiarchi (Bothriolepis,

Pterichthys), is thus not confirmed by recent work. This Order being now considered to belong definitely to the fishes, their appendages being true pectoral fins and their resemblance to the large paddle-like appendages of the Merostomata (Eurypterus or Pterygotus) being functional rather than structural.

9. The theory that a higher race of animals which was " predominant " arose directly from a lower race in the geological period which immediately preceded it, must, in the light of modern knowledge, be radically modified, since it is evident that the common ancestor of two highly differentiated and in many respects divergent classes must have been of a much simpler type than either of the two classes under consideration. Moreover, the divergence of the two classes must have taken place long before dominance of one class over the other could have existed as a factor in their evolution. Certain points of similarity in particular organs or systems seem to have been preserved in the two divergent classes, although even these when critically examined are found to present modifications in detail ; and the modifications or divergences are in general more pronounced in the phylogenetically older races and in adult animals as compared with their larval or embryonic stages. To take a concrete instance, the difference between the compound faceted eye of an arthropod and the inverted eye of an adult vertebrate is very great, and since the upright faceted eyes of certain arthropods were already highly evolved in some trilobites which were living in the Upper Cambrian period and since median eye tubercles have been found in both larval and adult specimens of Trinucleus and

Fig. 321. — Intracranial Surface of postmedian plate of asterolepis ornata. (after Stensio.)


other closely related forms of trilobites, it is evident that the distinction between median eyes and lateral eyes had occurred at a very early date and that the time required to produce the differentiation of the complex faceted eyes must place the actual origin of the lateral eyes of arthropods at a still earlier period.

The degree of differentiation of the lateral eyes of invertebrates varies greatly in different classes, and the divergence from the simpler types is greater in the adult animal than in the larva and in the more highly organized types of animal than in the more primitive.

Now the earliest known fossil vertebrates, the ostracoderms, agree with the invertebrate Eurypteridae in possessing both lateral and median eyes, and they were contemporary with each other, living in the sea under much the same conditions and in the same geological period. Comparisons were therefore made between the ostracoderms and the eurypterids, and between the living representatives of these two extinct classes, the cyclostomes, which are the direct descendants of the ostracoderms and certain of the more primitive types of cartilaginous fishes on the one hand, and the land scorpions, spiders, Limulus, and certain of the Crustacea on the other ; all of which resemble each other in possessing lateral and median eyes in the same relative positions with regard to each other and other organs in the head.

It will be unnecessary to refer to more than two or three of the more salient points which have recently been settled by a critical examination of the alleged similarities between the ostracoderm fishes and the eurypterids. One of these apparent similarities was the possession in Cephalaspid fishes of an exoskeleton which seemed to closely resemble the chitinous exoskeleton of eurypterids and Xiphosura. Now the exoskeleton of the fishes, whether it consists of denticles, scales, scutes, or " armour plating," consists of an outer layer of epidermal bone or of enamel, which covers a dermal bony stratum, or osteodentine ; and it will be recalled that in the development of a tooth the formation of the enamel is at the inner or deep end of the enamel cells or ameloblasts ; further, the increase in thickness of the enamel is by the laying down of new layers on the superficial surface of those which have already been deposited ; and also that the dentine which is formed on the surface of the dermal papilla by the odontoblasts is layed down in the reverse direction to the enamel, namely, from without inwards, the increase in thickness of the dentine being due to its formation at the outer or superficial ends of the odontoblasts. The shields or plates forming the armour plating of the ostracoderm fishes are of the nature of a vaso-dentine, and the


rhombic scales on the posterior part of the body, in some examples, e.g. Pteraspis (Fig. 322), were coated on their superficial aspect by an enamellike layer. In the formation of the chitinous exoskeleton of an arthropod, however, there is a secretion of a cuticular nature from the outer ends of the columnar hypoblast cells or deric epithelium, this becoming condensed forms a hard chitinous shell on the surface of the hypoblast. The shell thus consists of a thickened and hardened cuticle and differs both structurally and chemically from enamel and osteodentine. Chitin is a nitrogenous and carbohydrate substance allied in its composition to horn ; it may be impregnated with lime salts, but no true Haversian systems, such as those present in bone, are found in it. Increase in size of the animal including its appendages is obtained by a series of moults (ectdyses) in which the hardened cuticle undergoes softening and is cast off; the

Fig. 322. — Lateral Aspect of Pteraspis rostrata, an Ostracoderm Fish characterized by the absence of pectoral or pelvic flns, a hypocercal Tail, Large Plates or Scutes covering the Head and Anterior Part of the Body, and Rhombic Scales covering the Remaining Part of the Body and Tail.

The pineal plate is not perforated in P. rostrata, but in some specimens a pit is present on its internal surface. In P. monmouthensis a complete perforation is found. (E. Ivor White.)

growth of the animal taking place chiefly in the intervals between the moults ; whereas the increase in size of vertebrates which possess an exoskeleton is similar to that of the skull, a continuous process, taking place partly along the lines of suture between the plates and in the case of dermal bones which have sunk beneath the surface of the skin also by deposit of new bone on the surface of the old, and absorption of bone on the internal surface.

Another important distinction between the fishes and the palaeostracan arthropods is the existence of median dorsal and caudal fins in the former, as compared with the long, tapering caudal spine of the Xiphosura, as well as the presence in some, e.g. Asterolepis, Remigolepis, Bothriolepis, of a cartilaginous endoskeleton, having the structure of a true pectoral fin inside the bony plates forming the exoskeleton. Finally the existence of a notochord (Fig. 238, p. 341), and the vertebrate position of the heart and main blood-vessels relative to the alimentary canal are fundamental


differences which serve to place the ostracoderms definitely among the fishes, and not, as was formerly supposed, in an intermediate position within the direct line of descent of the vertebrates from a highly differentiated ancestral arthropod, such as Limulus, or a species resembling any other of the living arachnids.

Summary of Observation on the Development and Structure of the Human Pineal Organ

1. The pineal diverticulum first appears in human embryos of approximately 15 mm. length.

2. The apex of the diverticulum is primarily directed forwards.

3. The pineal outgrowth lies a short distance in front of the posterior commissure, and sometimes presents a constriction subdividing it into an anterior and posterior segment.

4. The whole thickness of the neural wall participates in the formation of the pineal evagination.

5. In some specimens there is an indication of the anterior segment being subdivided into right and left lobes.

6. The " anterior lobe " first described by Krabbe appears in embryos of about 22 mm. length as several neuro-epithelial buds which grow forward into the surrounding connective tissue.

7. A well-marked supra-pineal recess (dorsal sac) is present at the 22-mm. stage.

8. Transverse grooves, which are produced by folding of the roof of the aqueductus cerebri in the region of the posterior commissure, represent temporary infrapineal recesses.

9. Between the third and fourth months of foetal life there occurs an active proliferation of cells derived from the inner or ependymal zone of the pineal diverticulum. These grow outward in the form of cords, the component cells of which are arranged radially round a central axis which is destitute of nuclei. This is accompanied by a simultaneous ingrowth of vascular processes of mesenchyme.

10. A special mass of proliferating cells growing from the anterior wall of the main diverticulum gives rise to the solid anterior lobe of Krabbe, whereas the cords which grow from the fundus of the diverticulum form the principal solid part of the posterior lobe. The cavities at the base of the stalk and that of the posterior diverticulum appear to open out, and their lumina thus become incorporated in the cavity of the third ventricle, whereas the cavity of the main or anterior diverticulum, which may be cut off as the " cavum pineale," usually disappears.

11. The neuro-epithelial cells give rise to (1) the glia lining the fibrous capsule and covering the trabecular, (2) the parenchyma cells, and (3) the


neuroglial cells (astrocytes). The surrounding connective tissue and ingrowing vascular mesenchyme form the fibrous capsule and the connective tissue basis of the septa and finer trabecular, including the contained vessels. Many of the sinusoidal vessels in the central part of the pale vascular areas, which are seen in the earlier stages of development, disappear, leaving only a very fine capillary plexus in the parenchymatous tissue of the lobules.

12. The parenchymatous tissue in the adult consists of a reticulum of branched pineal cells, among which are a few neuroglial cells, chiefly of the astrocyte type. The " alveolar " appearance which is sometimes seen in adult specimens is due to the persistence of primary neuroepithelial cords, cross-sections of which appear as rosettes.

13. Cells and nerve-fibres belonging to the sympathetic system accompany the vessels entering and leaving the pineal organ ; and medullated nerve-fibres connect the habenular and posterior commissures with the parenchymatous tissue, but the exact mode of termination of their axons with regard to the pineal cells is not certain. True ganglion cells belonging to the central nervous system and having an axis cylinder process, although described by some authors, appear to be very rarely seen in the human pineal gland, but transitional forms exist, which are intermediate between true nerve ceils and parenchymatous cells. These are described as " neuronoid."

The experimental and clinical evidence with respect to function of the mammalian pineal body is at the present time too conflicting to allow of any definite conclusions being drawn. We know that before the age of puberty, more especially in boys, pineal tumours have sometimes been associated with premature growth in size of the body, precocious development of the genital organs, and the early appearance of secondary sexual characters. But it seems probable that certain other factors have been involved in the production of these symptoms — more particularly pressure, either direct or indirect, of the pineal tumour on neighbouring parts of the brain, such as the hypothalamus and pituitary region, combined with the irritative reflex effects produced by increased intracranial tension — and that the symptoms are not directly attributable to disturbance of any special function possessed by the pineal body itself. Moreover, a considerable number of cases have been reported in which sexual precocity and macrogenitosomia have been present but there has been no pineal tumour, and the reverse condition in which a pineal tumour has been present in young boys but unaccompanied by the Pellizzi syndrome. Further, that although some cases of premature development of the breasts in girls and gynecomastia in males have been reported, these con


ditions appear to have been absent in the majority of cases of pineal tumour.

An accurate knowledge of the immediate anatomical relations of the pineal body, is essential in order to clearly distinguish the symptoms due to implication of neighbouring parts and those due to a supposed special function of the pineal gland. Some of the structures in close relation with the pineal body are : the aqueduct of Sylvius, the quadrigeminal plate, the geniculate bodies, the nuclei and nerve tracts of the ventral part of the midbrain, the thalamencephalon, the hypothalamus and " portal system " of vessels supplying the pituitary gland, the cerebellum, and the related intracranial nerves and blood-vessels. The mere enumeration of these parts which are liable to be involved in a growth of the pineal body will indicate that when the pressure symptoms are eliminated from the total " symptom complex " accompanying the growth of such tumours there is little left in support of the contention that the human pineal gland has a regulating influence on the normal development of the body and the genital organs, and more especially in the direction of inhibiting or retarding their growth.

In Fig. 323 we have tried to show in a diagrammatic manner the general distribution of the different types of median and lateral eyes in the animal kingdom. We have not attempted to include in this scheme any of the aberrant forms of eye such as those met with on the back of the Chitons, or " coat-of-mail shells," or invertebrate eyes with inverted retina; such as those on the back of Oncidium or at the edge of the mantle in Pecten, since these are not specially concerned in the phylogeny of either the paired median or paired lateral eyes of vertebrates, and although of great interest in showing how special organs are sometimes evolved in anomalous situations in adaption to special needs, they do not assist in tracing the general evolution of the eyes of vertebrates. We hope that the diagram will be of some assistance in showing graphically how very far removed the more highly organized classes of living vertebrates are from the highly organized living invertebrates ; and, although the form and dimensions of the " tree " are not intended to accurately represent the periods of time which have elapsed since the divergence of the various classes took place in the course of evolution, that it will give some indication of the way in which certain of the simple types have persisted to the present day without, it may be presumed, having undergone marked modifications in general form and structure, while others have diverged from the primary simple type, but have nevertheless retained some of their older traits, which appear either in a simple form in the early larval condition, or may be present in the adult, in a modified and highly differentiated form. We have limited the term " parietal eye " to the parietal


sense-organ of vertebrates, and designated the median eyes of invertebrates as such, or as frontal, triplacodal, or entomostracan eyes. We do not, however, wish it to be inferred that we consider the parietal senseorgan of vertebrates has arisen quite independently of the median eyes









Parietal foramen well developed. paired lateral orbital cavities.












simple uprighteyes

types of simple upright eyes, lateral; dorsal; on edge of mantle, having ectodermal cellular lens & inverted retina. highly differentiated eyes in cephalopods.




Fig. 323. — Scheme indicating the General Distribution of Different Types of Median and Lateral Eyes in the Animal Kingdom.

of invertebrates. Further, we have used the term " parietal eye " in the singular although, as explained elsewhere, it may represent in some cases one member of a pair of median eyes or in other cases be formed by the fusion of the right and left members of a pair of primarily bilateral organs.








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550,000 OOO TO 700,000,000


















Fig. 324 t — Geological Chart indicating the Order in which Organs Sensitive to Light and various Types of Eye have been evolved, and also the Estimated Age in which the Different Classes of Animals have been found. (Modified from Scheme and Data published by Gaskell and

   The Pineal Organ (1940): 1 Introduction | 2 Historical Sketch | 3 Types of Vertebrate and Invertebrate Eyes | Eyes of Invertebrates: 4 Coelenterates | 5 Flat worms | 6 Round worms | 7 Rotifers | 8 Molluscoida | 9 Echinoderms | 10 Annulata | 11 Arthropods | 12 Molluscs | 13 Eyes of Types which are intermediate between Vertebrates and Invertebrates | 14 Hemichorda | 15 Urochorda | 16 Cephalochorda | The Pineal System of Vertebrates: 17 Cyclostomes | 18 Fishes | 19 Amphibians | 20 Reptiles | 21 Birds | 22 Mammals | 23 Geological Evidence of Median Eyes in Vertebrates and Invertebrates | 24 Relation of the Median to the Lateral Eyes | The Human Pineal Organ : 25 Development and Histogenesis | 26 Structure of the Adult Organ | 27 Position and Anatomical Relations of the Adult Pineal Organ | 28 Function of the Pineal Body | 29 Pathology of Pineal Tumours | 30 Symptomatology and Diagnosis of Pineal Tumours | 31 Treatment, including the Surgical Approach to the Pineal Organ, and its Removal: Operative Technique | 32 Clinical Cases | 33 General Conclusions | Glossary | Bibliography
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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Cite this page: Hill, M.A. (2021, May 7) Embryology Book - The Pineal Organ (1940) 32. Retrieved from

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