378 



THE PERIPHERAL NERVOUS SYSTEM 



Mesenchyma Lens vesicle Vitreous body Optic stalk Optic recess of brain 



^ 'V 'L ""'^7" ' 



' '-CV ' V/' 



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> /' '--^'^^i; 









1 of cornea Pigment layer of retina Nervous layer of retina 



Fig. 376. — A transverse section through the optic cup, stalk and lens of a 10 mm. human embryo. 



X 100. 



Epithelial layer of lev! Pigment layer of the retina 



Eitodi I m 



\ I nous layer of retina 



fe.. iChorioid fissure 



Mesenchyme 



Fig. 377. — Transverse section passing through the optic cup at the level of the chorioid fissure. 

 The central artery of the retina is seen entering the fissure and sending a branch to the proximal surface 

 of the lens; from a 12.5 mm. human embryo. X 105. 



cornea and its posterior epithelium, while the proximal mesenchyma (next the 

 lens) differentiates into the vascular capsule of the lens. The mesenchjmie sur- 

 rounding the optic cup is continuous with that which forms the cornea and later 



