Paper - Observations concerning the comparative anatomy of the diencephalon (1912): Difference between revisions
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==Introduction== | ==Introduction== | ||
The purpose of this article is to describe briefly in the {{diencephalon}} of the lemur and the {{cat}} certain cell groups already described by me in the human. It will be necessary to give a short statement of the different methods of dividing the diencephalor into nuclei, as based upon histological evidence. | The purpose of this article is to describe briefly in the {{diencephalon}} of the lemur and the {{cat}} certain cell groups already described by me in the human. It will be necessary to give a short statement of the different methods of dividing the diencephalor into nuclei, as based upon histological evidence. | ||
A division of the diencephalon based upon histological evidence will vary according to the method of interpretation. Two methods of division may be recognized: | A division of the diencephalon based upon histological evidence will vary according to the method of interpretation. Two methods of division may be recognized: | ||
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1. The topographical, by which the diencephalon is divided into many fields termed (in many cases erroneously) nuclei. These fields are for the most part determined by the splitting up of the gray matter by fiber masses. Such a division according to the gross, mechanical grouping of gray matter may be obtained from Nissl preparations as readily as those of WeigertPal, if the cell preparations are studied merely as the positive of the Weigert-Pal negative; unless the cell character is considered, the correspondence of the Nissl picture to that of the fiber preparation is no indication of the correctness of the resulting division. When so interpreted the two pictures must necessarily correspond. | 1. The topographical, by which the diencephalon is divided into many fields termed (in many cases erroneously) nuclei. These fields are for the most part determined by the splitting up of the gray matter by fiber masses. Such a division according to the gross, mechanical grouping of gray matter may be obtained from Nissl preparations as readily as those of WeigertPal, if the cell preparations are studied merely as the positive of the Weigert-Pal negative; unless the cell character is considered, the correspondence of the Nissl picture to that of the fiber preparation is no indication of the correctness of the resulting division. When so interpreted the two pictures must necessarily correspond. | ||
2. The second method of division is that employed by me in my monograph Uber die Kerne des menschlichen Diencephalon," and divides the diencephalon into primary nuclei. A primary nucleus I have defined as a more or less circumscribed group of cells having an identical (histological) character. With our present knowledge we are justified in setting aside a group of cells as a primary nucleus, only when the histological character of these cells differs markedly from that of the surrounding cells. And if we take into consideration the fact that certain | 2. The second method of division is that employed by me in my monograph "''Uber die Kerne des menschlichen Diencephalon''," and divides the diencephalon into primary nuclei. A primary nucleus I have defined as a more or less circumscribed group of cells having an identical (histological) character. With our present knowledge we are justified in setting aside a group of cells as a primary nucleus, only when the histological character of these cells differs markedly from that of the surrounding cells. And if we take into consideration the fact that certain purely mechanical influences (such as compression by dense fiber masses) may change the histological picture of a cell, we are justified in assuming: that a fairly well circumscribed group of cells havhig an identical histological character (primary nucleus) has a definiie primary function, and further, that two primary nuclei whose cells show a marked difference in histological character possess a different primary function. To sum up: The division into primary nuclei depends upon (a) an entire indifference to the splitting up of cell masses by bundles of fibers, and (b) the bringing together of cells with an identical histological character to constitute a primary nucleus, even when these cells are intermingled with those of one or more other primary nuclei. The purpose of such a division is: (a) to prepare a basis for finer experimental and pathological study, and (b) by the location of certain definite cell types to enable us to state their function, even when these cells are not directly accessible to experiment. | ||
In making a comparative study of the diencephalon of different animals, one is impressed with the great difference in the structure and grouping of the cells. This difference is greatest in the thalamus, and since its development depends upon that of the cerebral cortex, these dissimilarities are to be expected. To give an adequate description of the relations between the thalamus of the cat and of man, would require a careful' study of several intermediate forms. But the hypothalamus is an older part of the diencephalon, and consequently we find here better differentiated cell groups, which show comparatively slight variations in different animals. Therefore it is possible to compare certain primary nuclei in the h^'pothalamus of the cat and man, with the aid of only the lemur as an intermediate form. Moreover the recent article of Friedemann on cercopithecus affords further material for such a comparison. | In making a comparative study of the diencephalon of different animals, one is impressed with the great difference in the structure and grouping of the cells. This difference is greatest in the thalamus, and since its development depends upon that of the cerebral cortex, these dissimilarities are to be expected. To give an adequate description of the relations between the thalamus of the cat and of man, would require a careful' study of several intermediate forms. But the hypothalamus is an older part of the diencephalon, and consequently we find here better differentiated cell groups, which show comparatively slight variations in different animals. Therefore it is possible to compare certain primary nuclei in the h^'pothalamus of the cat and man, with the aid of only the lemur as an intermediate form. Moreover the recent article of Friedemann on cercopithecus affords further material for such a comparison. | ||
The | In addition to the five series of the human diencephalon, which have been described in a previous article, the present description is based upon three complete transverse series of the cat, and one of the human. All series were stained with {{toluidine blue}}. | ||
The human hypothalamus I havo subdivided into the following primary nuclei: (1) Corpus hypothalamicum, (2) Nucleus medialis corporis mammillaris, (3) Nucleus intercalatus corporis mammillaris, (4) Nucleus mammillo-infundibularis, (5) Nucleus paraventricularis hypothalami, (6) Substantia reticularis hypothalami, (7) Substantia g;risea ventriculi tertii. All of these nuclei may be identified in the cat and lemur, although the picture is less clear than in the human. | |||
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Under the name of substantia reticularis hypothalami may be classed certain cells of diverse histological character which are distributed more or less diffusely throughout the hypothalamus. It seems inadvisable to attempt a thorough description of these cells until more material is available. But one point must be mentioned, to which I have already called attention in my monograph on the human diencephalon. The hypothalamus of the cat and lemur, just as in man, is characterized by containing the only cells in the entire diencephalon of a motor structure. These cells are similar to the motor cells of the anterior quadrigeminal body, and form a direct continuation of these cells into the hypothalamus. Of course it is not probable that these cells are part of peripheral neurones; the modified histological picture is | Under the name of substantia reticularis hypothalami may be classed certain cells of diverse histological character which are distributed more or less diffusely throughout the hypothalamus. It seems inadvisable to attempt a thorough description of these cells until more material is available. But one point must be mentioned, to which I have already called attention in my monograph on the human diencephalon. The hypothalamus of the cat and lemur, just as in man, is characterized by containing the only cells in the entire diencephalon of a motor structure. These cells are similar to the motor cells of the anterior quadrigeminal body, and form a direct continuation of these cells into the hypothalamus. Of course it is not probable that these cells are part of peripheral neurones; the modified histological picture is against this. But it is highly probiiblc that they are more or less directly associated with peripheral motor neurones. This view is strengthened by the fact that in the substantia reticuhiris of the hypothalamus numerous transition types of cells occur, from those entirely devoid of motor structure to such as can only with difficulty be distinguished from genuine peripheral motor cells. Another very significant fact is that no trace of motor structure can be detected in any of the cells of the thalamus, epi-, or metathalamus, which are exactly those -portions of the diencephalon which are known to contain sensory centers. | ||
==Conclusions== | ==Conclusions== | ||
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Malone EF. Observations concerning the comparative anatomy of the diencephalon. (1912) Anat. Rec. 6: 281-290.
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Observations Concerning the Comparative Anatomy of the Diencephalon
Edward F. Malone
From the Anatomical Laboratory uf the University of Cincinnati
Four Figures
Introduction
The purpose of this article is to describe briefly in the diencephalon of the lemur and the cat certain cell groups already described by me in the human. It will be necessary to give a short statement of the different methods of dividing the diencephalor into nuclei, as based upon histological evidence.
A division of the diencephalon based upon histological evidence will vary according to the method of interpretation. Two methods of division may be recognized:
1. The topographical, by which the diencephalon is divided into many fields termed (in many cases erroneously) nuclei. These fields are for the most part determined by the splitting up of the gray matter by fiber masses. Such a division according to the gross, mechanical grouping of gray matter may be obtained from Nissl preparations as readily as those of WeigertPal, if the cell preparations are studied merely as the positive of the Weigert-Pal negative; unless the cell character is considered, the correspondence of the Nissl picture to that of the fiber preparation is no indication of the correctness of the resulting division. When so interpreted the two pictures must necessarily correspond.
2. The second method of division is that employed by me in my monograph "Uber die Kerne des menschlichen Diencephalon," and divides the diencephalon into primary nuclei. A primary nucleus I have defined as a more or less circumscribed group of cells having an identical (histological) character. With our present knowledge we are justified in setting aside a group of cells as a primary nucleus, only when the histological character of these cells differs markedly from that of the surrounding cells. And if we take into consideration the fact that certain purely mechanical influences (such as compression by dense fiber masses) may change the histological picture of a cell, we are justified in assuming: that a fairly well circumscribed group of cells havhig an identical histological character (primary nucleus) has a definiie primary function, and further, that two primary nuclei whose cells show a marked difference in histological character possess a different primary function. To sum up: The division into primary nuclei depends upon (a) an entire indifference to the splitting up of cell masses by bundles of fibers, and (b) the bringing together of cells with an identical histological character to constitute a primary nucleus, even when these cells are intermingled with those of one or more other primary nuclei. The purpose of such a division is: (a) to prepare a basis for finer experimental and pathological study, and (b) by the location of certain definite cell types to enable us to state their function, even when these cells are not directly accessible to experiment.
In making a comparative study of the diencephalon of different animals, one is impressed with the great difference in the structure and grouping of the cells. This difference is greatest in the thalamus, and since its development depends upon that of the cerebral cortex, these dissimilarities are to be expected. To give an adequate description of the relations between the thalamus of the cat and of man, would require a careful' study of several intermediate forms. But the hypothalamus is an older part of the diencephalon, and consequently we find here better differentiated cell groups, which show comparatively slight variations in different animals. Therefore it is possible to compare certain primary nuclei in the h^'pothalamus of the cat and man, with the aid of only the lemur as an intermediate form. Moreover the recent article of Friedemann on cercopithecus affords further material for such a comparison.
In addition to the five series of the human diencephalon, which have been described in a previous article, the present description is based upon three complete transverse series of the cat, and one of the human. All series were stained with Toluidine blue.
The human hypothalamus I havo subdivided into the following primary nuclei: (1) Corpus hypothalamicum, (2) Nucleus medialis corporis mammillaris, (3) Nucleus intercalatus corporis mammillaris, (4) Nucleus mammillo-infundibularis, (5) Nucleus paraventricularis hypothalami, (6) Substantia reticularis hypothalami, (7) Substantia g;risea ventriculi tertii. All of these nuclei may be identified in the cat and lemur, although the picture is less clear than in the human.
As some of them have been described only once (in cercopithecus) since their existence was pointed out by me in my monograph on the human diencephalon, it seems advisable to mention certain observations, although a thorough description must await the preparation of further material.
The corpus mammillare in the cat and in the lemur presents the same nuclei described by me in man, and more recently by Friedemann in cercopithecus:
1. The ganglion mediale corporis mammillaris, which is composed of small cells and occupies the greater part of the mamillary body, is well known and may at once be dismissed.
2. The nucleus mammillo-infundibularis corresponds in part probabh' to the lateral ganglion of the authors. But in addition to forming the lateral portion of the mammillary body, its cells, which through their histological character can be distinguished from the surrounding cells, extend in a dorsal and oral direction into the region of the infundibulum. The existence of this nucleus has been confirmed by Friedemann, who adopts for it the name here given. This nucleus is less well developed in the cat and the lemur than in man, and does not stand out so distinctly.
3. The nucleus intercalatus corporis mammillaris is in the cat and lemur relatively better developed than in man. On the other hand it is not always so easily distinguished from the lateral ganglion (nucleus mammillo-infundibularis). This nucleus consists of a round or oval group of cells, which in its caudal portion lies on the latero-ventral margin of the corpus mammillare; it extends in a dorso-oral direction between the medial and lateral ganglion. Whether the nucleus accessorius, which Kolhker has described in man, is identical with my nucleus intercalatus, is doubtful, since according to Kolliker the cells of the nucleus accessorius are smaller than those of the other two groups of the corpus mammillare; the cells of the nucleus intercalatus are on the contrary larger than those of the medial ganglion. Since Kolliker has not given any accurate description of these cells, nor of the extent of this cell group, it seems probable that he has described one of the islands of cells often mechanically cut off bj^ a fiber mass from the medial ganglion. Friedemann describes a nucleus intercalatus in cercopithecus, and adopts this name, after discussing the nucleus accessorius of Kolliker.
An exceedingly sharply defined group of cells has been described by me in man under the name of 'nucleus paraventricularis hypothalami'. It consists of a compact column of large deeply staining cells, and lies near the third ventricle. It is well developed in the cat and lemur. Under the same name this nucleus has been recently described in cercopithecus by Friedemann. It probably corresponds to the nucleo sub ventricular described by Cajal in the rabbit. Possibly the nucleus paraventricularis hypothalami corresponds to the nucleus subcommissurahs described by Ziehen in marsupials.
Under the name of substantia reticularis hypothalami may be classed certain cells of diverse histological character which are distributed more or less diffusely throughout the hypothalamus. It seems inadvisable to attempt a thorough description of these cells until more material is available. But one point must be mentioned, to which I have already called attention in my monograph on the human diencephalon. The hypothalamus of the cat and lemur, just as in man, is characterized by containing the only cells in the entire diencephalon of a motor structure. These cells are similar to the motor cells of the anterior quadrigeminal body, and form a direct continuation of these cells into the hypothalamus. Of course it is not probable that these cells are part of peripheral neurones; the modified histological picture is against this. But it is highly probiiblc that they are more or less directly associated with peripheral motor neurones. This view is strengthened by the fact that in the substantia reticuhiris of the hypothalamus numerous transition types of cells occur, from those entirely devoid of motor structure to such as can only with difficulty be distinguished from genuine peripheral motor cells. Another very significant fact is that no trace of motor structure can be detected in any of the cells of the thalamus, epi-, or metathalamus, which are exactly those -portions of the diencephalon which are known to contain sensory centers.
Conclusions
- Among the cell groups of the hypothalamus of the cat and the lenmr the following primary nuclei may be identified with similarly named nuclei described in my monograph on the human diencephalon: (1) Ganglion mediale corporis mammillaris, (2) Nucleus mammillo-infundibularis, (3) Nucleus intercalatus coi-poris mammillaris, (4) Nucleus paraventricularis hypothalami, (5) Substantia reticularis hypothalami.
- Cells of an undoubted motor structure occur in the hypothalamus of the cat, lemur and man. Such cells are entirely absent from the other divisions of the diencephalon.
Bibliography
(For full bibliography see papers of Friedemann and myself)
Cajal, Ramon y 1904 Textura del sistema nervioso, etc.
Friedemann, ISl. 1911 Die Cytoarchitektonik des Zwischenhirns derCercopitheken mit besonderer Beriicksichtigung des Thalamus opticus. Journal fiir Psychologie und Neurologie, Bd. 18, Erganzungsheft 2.
KoLLiKER, A. 1896 Handbuch der Gewebelehre, Bd. 2.
Maloxe, E. F. 1910 tjber die Kerne des menschlichen Diencephalon. Aus dem Anhang zu den Abhandlungen der konigl. preuss. Akademie der Wissenschaften.
Ziehen, Zentralnervensystem der Monotremen und Marsupialer. Zoologische Forschungsreisen nach Australien und dem malayischen Archipel, von Richard Semon, Bd. 3.
Explanation of Figures
The figures represent cross sections through the human diencephalon. Drawings of the cat and the lemur have not been included, since they would necessitate a more definite expression of facts than would be justified by the amount of material at present available. The outlines of the drawings were made with aid of the Edinger drawing apparatus, and the details filled in under control of the microscope.
The original magnification was 10 diameters. Fig. 1. has been reduced to 3.75, and figs. 2 to 4 to 3.3 diameters; the magnification of the cells is much greater. The drawings show merely the position of the various nuclei, and the arrangement of the cells within each nucleus.
Abbreviations
com.med., comissura media . c.sth. corpus subthalamicum
f. fornix
ggl.hab., ganglion habenulae
ggl.med.c.mam., ganglion mediale corporis mammillaris
g.o.b. ganglion opticum basale (so called)
n.c, nucleus caudatus
n.cs.th., nucleus communis thalami
n.cs.th. {dors.), nucleus communis thaiami, pars dorsalis
n.cs.th. (lat.), nucleus communis thalami, pars lateralis
n.cs.th. (med.), nucleus communis thaiami, pars medialis
n.i.c.niam., nucleus intercalatus corporis mammillaris
n.mg.th.{arc.), nucleus magnocellularis thalami, pars arcuata
tr. th. mam., tractus
n.tng.th.ipr.), nucleus magnocellularis thalami, pars principalis
n.mam.infd., nucleus mammillo-infundibularis
n.pmd.th., nucleus paramedianus thalami
pped.lat., nucleus peripeduncularis lateralis (Jacobsohn)
n.pv.hyp., nucleus paraventricularis hypothalami
n.pv.ih., nucleus parvocellularis thalami
n.r.th., nucleus reuniens thalami
n.rub., nucleus ruber
s.gr III, substantia grisea ventriculi tei'tii, pars inferior
s. gr III, substantia grisea ventriculi tertii, pars superior
s.n., substantia nigra
s.ret.hyp., substantia reticularis hypothalami
t., cells of the telencephalon thalamo-mammillaris
Plate 4
Cite this page: Hill, M.A. (2024, April 19) Embryology Paper - Observations concerning the comparative anatomy of the diencephalon (1912). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Observations_concerning_the_comparative_anatomy_of_the_diencephalon_(1912)
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