File:Wen1928-Fig07.jpg

Fig. 7 Lateral Views of the Brain

A, 16—somite C.C.470;

B, 17~somite H951;

C, 22—somite H1093—all drawn from models and reduced to a magnification of 66% diameters. Note the absolute decrease in the size of the optic vesicle and the relations of the midbrain to the cranial fiexnre.

A’, B’. C’, are sections (nos. 28, 25, and 34, respectively) taken from the corresponding embryos and magnified 66% times. The region which in external view appears as optic vesicle is deeply stippled.

Externally, the optic vesicle first appears to spring from the greater part of the forebrain (fig. 7, A) and extends laterally, dorsally, and slightly caudad. Soon each vesicle is marked off from the forebrain wall by a deeper, caudally located groove and a shallow rostral sulcus (fig. 7, B). With the separation of the vesicle from the brain wall, these grooves become ventral and dorsal in position with reference to the forebrain, but not the embryo as a whole, as may be seen in figure 7, 0. They may accordingly be termed ventral and dorsal limiting sulci, respectively. In the 17 somite embryo the more caudal ventral sulcus, beginning almost at the torus, extends dorsally behind the optic vesicle and has begun to arch over it to become continuous with the dorsal sulcus which fades out at about the middle of the vesicle. From the ventricular surface we see (fig. 4) the optic ventricle opening into the third ventricle by a large oval orifice, bounded caudally (ventrally) by a strongly indented ridge which corresponds to the ventral limiting sulcus.

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Reference

Wen IC. The anatomy of human embryos with seventeen to twenty-three pairs of somites (1928) J. Comp. Neural., 45: 301-376.

Cite this page: Hill, M.A. (2024, April 27) Embryology Wen1928-Fig07.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Wen1928-Fig07.jpg

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