The origin and development of the umbilical cord, and its relation to the amnion / by James Foulis, M.D.

  • Foulis, James.
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: The origin and development of the umbilical cord, and its relation to the amnion / by James Foulis, M.D. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    whole rump end of such an embryo is tightly encased in the amnion. A study of transverse sections carried through the root of the ventral string, or Bauchstiel, and through the rump end of the embryo, makes it perfectly clear that it is a mistake to de- scribe the ventral string as a continuation of the tail end of the embryo towards the chorion. The external genital organs, the anus, and tail develop in connection with this rump end of the embryo, but distally to the attachment of the amnion at the root of the Bauchstiel as the latter comes off from the ventral surface of the embryo. In all the early embryos examined, and they were many, this rump end was well marked, and in every case the amnion was found to embrace it closely, and then turn forward some distance to be attached to the root of the ventral string or Bauchstiel. This tail or rump end of the embryo is probably produced at an earlier stage when the hind gut is being formed. According to Quain, all the three la>'ers of the blastoderm are involved in the forward growth and overfolding which produces the head of the embryo, so that a prolongation from the blastoderm cavity, which is, of course, lined by hypoblast, becomes included in the head, and the anterior part of the primitive alimentary canal, ox fore gut, is thereby produced. Formed in this way, its front end is neces- sarily blind, and for a long time there is no mouth nor any communication between the fore gut and the exterior of the em- bryo The mouth becomes formed later by an invagmation from the exterior. Lastly, at the tail end of the embryo a hind gut is produced. In most mammals and birds it is produced by a folding over of the tail end of the embryo like that which occurs at the head to enclose the fore gut. The hind gut remains for a considerable time blind, until the anus becomes formed by invagination from the exterior. This explanation of the formation of the rump end of the embryo, namely, by a folding over of the blastodermic layers at an early stage to enclose a hypoblastic hmd gut also ex- plains how it is that the Bauchstiel which contains the tubular hypoblastic diverticulum from the intestine, comes off from the ventral surface of the embryo at some distance from its caudal or rump end, and we know that the external genital organs, the anus and the tail are formed externally to the root of the Bauchstiel ; but it also explains how the amnion, after embracing the rump end of the embryo, appears to be