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. The development of the chick; an introduction to embryology . So/)/. Sp-pl. Fig. 70. — Mediun lungitudiiuil section through the hind end of an embryoof about 21 pi., -Vnal })hite. an. t., Anal tube. p. i. p., Posterior intestinal B., Tail-bud. t. f. Sopl., Tail fold in the Soniatopleure. t. f. Sppl., Tailfold in the .splanchnopleure. Other abbreviations as before. elongates forwards. There remains then an open portion of thealimentary tract, where its walls are continuous with the extra-embryonic splanchnopleure or yolk-sac. This is known as theyolk-stalk. The entrance from t
. The development of the chick; an introduction to embryology . So/)/. Sp-pl. Fig. 70. — Mediun lungitudiiuil section through the hind end of an embryoof about 21 pi., -Vnal })hite. an. t., Anal tube. p. i. p., Posterior intestinal B., Tail-bud. t. f. Sopl., Tail fold in the Soniatopleure. t. f. Sppl., Tailfold in the .splanchnopleure. Other abbreviations as before. elongates forwards. There remains then an open portion of thealimentary tract, where its walls are continuous with the extra-embryonic splanchnopleure or yolk-sac. This is known as theyolk-stalk. The entrance from the yolk-sac into the fore-gutis known as the anterior intestinal portal, and that from theyolk-sac into the hind-gut as the posterior intestinal portal (). At the 27 s stage the yolk-stalk is long and narrow (); the stems of the splanchnic (omphalo-mesenteric) veins runto the heart in its anterior portion, and the ()nii)h;ilo-mesentencarteries pass out about its center. As it gradually closes, thestems of the omjihalo-mesenteric arteries and ve
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