. A laboratory manual and text-book of embryology. Embryology. TRANSVERSE SECTIONS OF A TEN MM. PIG EMBRYO 133 each section is indicated by guide lines on Fig. 123. The student should compare this with Figs. 113 and 118, and orient each section with reference to the embryo as a whole. Keep in mind the fact that the transverse sections are drawn from the cephalic surface so that the right side of the figure is the left side of the em- bryo. Transverse Section through the Eyes and Otocysts (Fig. 124).—The brain is sectioned twice, lengthwise through the myelencephalon, transversely through the f
. A laboratory manual and text-book of embryology. Embryology. TRANSVERSE SECTIONS OF A TEN MM. PIG EMBRYO 133 each section is indicated by guide lines on Fig. 123. The student should compare this with Figs. 113 and 118, and orient each section with reference to the embryo as a whole. Keep in mind the fact that the transverse sections are drawn from the cephalic surface so that the right side of the figure is the left side of the em- bryo. Transverse Section through the Eyes and Otocysts (Fig. 124).—The brain is sectioned twice, lengthwise through the myelencephalon, transversely through the fore-brain. The brain wall shows differentiation into three layers: (1) ah inner cpcndymal layer densely MyelcncephaJon n ! Ganq n access. Fig. 123.—Reconstruction of a 10 mm. pig embryo, showing the chief organs of the left side. The numbered lines indicate the levels of transverse sections shown in the corresponding figures (124-138). For the names of the various structures not lettered see Fig. 118. X S. Gang, and n. access., ganglion and n. accessorius; Gang. sup. n. g., superior ganglion of glossopharyngeal nerve; Pidm. artery, pul- monary artery. cellular; (2) a middle mantle layer of nerve cells and fibers; (3) an outer marginal layer chiefly fibrous. These same three layers are developed in the spinal cord. A thin vascular layer differentiated from the mesenchyma surrounds the brain wall and is the anlage of the pia mater. The myelencephalon shows three neuromeres in this section. The telencephalon is represented by the paired cerebral hemispheres, their cavities, the lateral ventricles, connecting through the interventricular foramina with the third ventricle of the dicnccphalon. Close to the ventral wall of the diencephalon is a section of the anterior lobe of the hypophysis (Rathke's pocket). Lateral to the diencephalon is the optic cup and lens vesicle of the eye, which are sec- tioned caudal to the optic stalk. The outer layer of the optic cup forms th
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectembryology, bookyear1
