File:Florian1930-text-fig06.jpg

Text-fig 6. Schemes of the chief stages in the development of the human embryo

In stage 6 (text-fig. 6, corresponding approximately with the embryo Peh. 1-Hochstetter, Rossenbeck, 1923) a new diverticulum is seen extending almost vertically upwards from the caudo-dorsal extremity of the yolk-sac in to the stalk mesoderm. I propose to speak of this as the allanto-enteric diverticulum since its proximal part represents the later hind-gut, its distal portion the entodermal allantoic canal. The proximal part coincides in position with the cloacal membrane ,furnishing its entodermal layer,whilst the allantoic canal is situated caudally to that membrane. The allanto-enteric diverticulum in this stage appears at first sight to be very similar to the diverticulum described in stage 4, which has been regarded by many authors, including myself, as the allantoic primordium, but there is a very important difference between the two, apart from the fact that the one is transitory, the other permanent. The cloacal membrane is situated in stage 4 at the end of the diverticulum there present, but in stage 6 it lies at the opening of the diverticulum into the yolk-sac cavity. The part of the diverticulum caudal to the cloacal membrane (the above-mentioned "allantoic" canal) is, therefore, in stage 4 not yet present. The axis of the stalk is now situated caudally to the amniotic cavity and its tip is directed to the upper or caudal end of the allantoic canal.

Ectoderm black; entoderm lined horizontally, primitive streak vertically, head process and chorda plate obliquely. Mesoderm dotted. The axis of the connecting stalk is marked by an arrow. The limits of the connecting stalk are marked by * and ʘ, the limits of the umbilical stalk by + and ʘ). The direction of the extension of the amniotic cavity towards the connecting stalk is marked by arrows. The parts of the allantois and of the axis of the connecting stalk situated out of the median plane are finely dotted. A. Connecting stalk; B. umbilical stalk; Cl.m. cloacal membrane.

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Links: Text-fig 1 | Text-fig 2 | Text-fig 3 | Text-fig 4 | Text-fig 5 | Text-fig 6 | Text-fig 7 | Text-fig 1-7 | Text-fig 8 | Text-fig 9 | Text-fig 8-9 | Florian 1930 | Historic Embryology Papers

Reference

Florian J. The formation of the connecting stalk and the extension of the amniotic cavity towards the tissue of the connecting stalk in young human embryos. (1930) J. Anat., 64: 454-476.

Cite this page: Hill, M.A. (2024, April 27) Embryology Florian1930-text-fig06.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Florian1930-text-fig06.jpg

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