. The development of the chick; an introduction to embryology . FiG. 6. — Primordial follicle from theovary of the hen. (After Holl.) Gr., Granulosa. N., Nucleus. Str.,Stroma. Y. N., Yolk nucleus. 28 THE DEVELOPMENT OF THE CHICK line membrane (Fig. 7). It becomes elliptical, and later the outersurface is flattened against the vitelline membrane, the innersurface remaining convex (Fig. 8). The point on the surface towhich the germinal vesicle migrates is situated away from thesurface of the ovary, and thus in the position of the pedicle of , V Jtr^r .J*- -*^, V ft Ou/. Fig. 7. — Section o
. The development of the chick; an introduction to embryology . FiG. 6. — Primordial follicle from theovary of the hen. (After Holl.) Gr., Granulosa. N., Nucleus. Str.,Stroma. Y. N., Yolk nucleus. 28 THE DEVELOPMENT OF THE CHICK line membrane (Fig. 7). It becomes elliptical, and later the outersurface is flattened against the vitelline membrane, the innersurface remaining convex (Fig. 8). The point on the surface towhich the germinal vesicle migrates is situated away from thesurface of the ovary, and thus in the position of the pedicle of , V Jtr^r .J*- -*^, V ft Ou/. Fig. 7. — Section of an ovarian ovum of the pigeon; drawn from a prepara-tion of Mr. J. T. Patterson. The actual dimensions of the ovum are mm. f. s., Stalk of follicle. G. V., Germinal vesicle. Gr., Granulosa. L.,Latebra. p. P., Peripheral protoplasm, pr. f., Primordial folhcles. Th. ex.,Theca externa. Th. int., Theca interna. Y. Y., Yellow yolk. Z. r., Zonaradiata. the follicle, when the latter projects from the surface of the ovary(Fig. 7). This determines the position of the future germ nucleus increases in size with the growth of the ovum; in theyoungest ovocytes its diameter is about 9 /x; in the ripe ovum it isflattened and may measure 455 ju in diameter by 72 ^ in thickness. THE EGG 29 While the nucleus is still near the center of the egg a verydense deposit of extremely fine granules is formed around it, andgradually extends out towards the periphery of the cell, butdoes not involve the peripheral layer of protoplasm. This centralaggregation of yolk-gran
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