Book - The Pineal Organ (1940) 9

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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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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)

The Pineal Organ - Eyes of Invertebrates

Chapter 9 The Eyes of Echinodermata

This phylum includes the star-fishes, Asteroidea ; the sea-urchins, Echinoidea ; feather-stars, Crinoidea ; and sea-cucumbers, Holothuroidea.

Eye-spots are found at the bases of the terminal tentacles, which spring from the tip of each of the five rays of a starfish (Fig. 60). They are of a bright red colour and form a slight elevation which is called the optic cushion (Fig. 61). On microscopic examination, the cuticular epithelium is seen to be specially modified in this area, and to line a series of small conical pits or ocelli. The cells are elongated and form a single layer. Their outer ends are directed towards the hollow of the pit, and are clear and rod-like. The middle portion of each cell is deeply pigmented, while the outer part which contains the nucleus is in relation with a subepidermal plexus of nerve-fibres ; this is continuous with the radial nerve of the corresponding arm which terminates in the central pentagonal nervering surrounding the mouth.




Fig. 60. Semi-diagrammatic drawing of a very young Asteroid, showing the positions of the optic cushions — oc. — at the base of each terminal tentacle, or. : mouth.

Each eye-spot is connected by the superficial or epidermal radial nerve of the corresponding arm with one of the angles of the " nerve pentagon " which surrounds the mouth. The ocelli are of a bright red colour.

(From Arnold Lang, Textbook of Comparative Anatomy.)


Fig. 61. — Section through the optic cushion at the base of the terminal tentacle of an asteroid.

c. : cuticle of the optic cup. ep. t. : epithelium of tentacle.

p.c. : pigment cells. I.n.f.: layer of nerve fibres.

cut. : cuticle of the epithelium of c.t. : connective tissue.

the tentacle. ep. t. c. : epithelium of tentacle canal.


In the sea-urchins slight elevations are present on the " ocular plates." These are situated in a position which corresponds to that of the " optic cushions " of star-fishes, namely at the tips of the five ambulacral zones of the shell, in the " periproctal " region, round the anus. The ambulacral zones are homologous with the rays of a star-fish ; the rays having, as it were, been bent backwards towards the anal or aboral pole, which lies opposite the oral pole on which the mouth is found.


The small elevation on the " ocular plate," although it was at one time thought to be a rudimentary eye, has, however, been shown to be a vestigial tentacle. This vestigial tentacle, however, corresponds to the " terminal tentacle " of the star-fish at the base of which the " optic ganglion " is developed.



   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
Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
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. (2020, October 21) Embryology Book - The Pineal Organ (1940) 9. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_The_Pineal_Organ_(1940)_9

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