File:Ewart1897 04.jpg

Fig. 4. Represents a five-weeks (35 days) Horse Embryo

Note that the absorbing area (a, b, c) is smaller than in the 28 days' embryo, while the capacity of the allantois is greater. Delicate villi (c.v.) now project from the allantois towards the yolk sac, and the girdle (t.g.) now consists of distinct nearly parallel ridges, with furrows between — these ridges, as well as the ridges of the ring (an.) around the absorbing area, have been exaggerated in the drawings.

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Reference

Ewart, J.C. A Critical Period in the Development of the Horse. London: Adam and Charles Black (1897).