On the Pate of the Blastopore and the Presence of a Primitive Streak in the Newt (Triton cristatus)
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چکیده
A.—At the close of segmentation the blastopore is placed in the normal position at the hind end of the embryo. With the greater growth of the dorsal surface, consequent on the appearance of the medullary folds and formation of the medullary canal, it comes to occupy a place on the ventral surface at some distance from the hind end (v i d e fig. 11). Its distance from the hind end increases as development goes on (vide figs. 12, 13). The tail
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تاریخ انتشار 2006