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Fig. 35. Diagram of dissection of chick of about 50 hours

(Modified from Prentiss.)

The spianchnopleure of the yolk-sac cephalic to the anterior intestinal portal, the ectoderm of the left side of the head, and the mesoderm in the pericardial region have been dissected away. A window has been cut in the spianchnopleure of the dorsal wall of the mid-gut to show the origin of the omphalomesenteric arteries.

While the secondary optic vesicles are usually spoken of as the optic cups, they are not complete cups. The invagination which gives rise to the secondary optic vesicles, instead of beginning at the most lateral point in the primary optic vesicles, begins at a point somewhat toward their ventral surface and is directed mesiodorsad. As a result the optic cups are formed without any lip on their ventral aspect. They may be likened to cups with a segment broken out of one side. This gap in the optic cup is the choroid fissure (Fig. 35).

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Patten BM. The Early Embryology of the Chick. (1920) Philadelphia: P. Blakiston's Son and Co.

Cite this page: Hill, M.A. (2019, August 26) Embryology Patten035.jpg. Retrieved from

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G

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