Embryology - 16 Apr 2024 Expand to Translate
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Gladstone RJ. and Wakeley C. The Pineal Organ. (1940) Bailliere, Tindall & Cox, London. PDF

Historic Disclaimer - information about historic embryology pages
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 6 The Eyes of Round Worms, Nemathelminthes

Many of these, such as Ascaris lumbricoides, A . suilla, A . megalocephala, Dochmius duodenalis, Oxyuris, Trichina spiralis, Filaria medianensis

Fig. 55. A — Dorsal aspect of head of Sagitta bipunctata, showing paired eyes connected by optic nerves with the brain. E. : eye. Ol. n. : olfactory nerve.

Op. n. : optic nerve. Br. : brain.

Ol. 0. : olfactory organ.

B — Section through eye of Sagitta hexaptera, after O. Hertwig. Ep. : cutaneous epithelium. Rh. : rods.

L. : lens. Ret. c. : retinal cells.

P. : pigment.

(guinea worm), F. sanguinis hominis, and Trichocephalus dispar, are parasitic and have no eyes. Among the non-parasitic round worms, which live in fresh-water near the sea-shore or on the surface of the ocean, we may mention the arrow worm, Sagitta hexaptera, which has two eyes placed laterally on the dorsal surface of the head. Each eye is rounded in form and contains three biconvex lenses ; these are separated by a tri-radiate pigment zone and are surrounded by converging rod-like sensory cells. The latter end in nerve fibres which are grouped together into a pair of optic nerves which end in the cerebral ganglion (Fig. 55). This triradiate arrangement of the pigment zone, and of the refractile elements and sensory cells of the paired eyes of Sagitta hexaptera, is very similar to that which is seen in the median triplacodal eyes of arthropods (Figs. 248, 249, 250), and like these it appears to have originated by the fusion of 3 separate ocelli, see pp. 360, 361, 362. !

1 Hertwig, O., 1880, Die Chaetognathen. Gustav Fischer, Jena.

Historic Disclaimer - information about historic embryology pages
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. (2024, April 16) Embryology Book - The Pineal Organ (1940) 6. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_The_Pineal_Organ_(1940)_6

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