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Fig. 271. Sections through the wall of the caecum

Of (a) a rabbit 2.5 days and (b) 5 days after birth, showing the development of the lymph follicles.

Stohr.

Lymphoid infiltration in the stroma; r, wandering cells in the epithelium; 2, lymphoid cells in the core of a villus.


In the development of the lymph follicles in the gastrointestinal tract the same question arises as in the case of the tonsils and thymus. Are the lymphoid cells of mesodermal or of entodermal (epithelial) origin? Evidence at present favors the mesodermal origin. In the case of Peyer's patches, collections of lymphoid cells appear near the blood vessels in the stroma and neighboring parts of the submucosa. These increase in extent, the lymphoid cells dividing actively, and grow into the bases of some of the villi and deeper into the submucosa (Fig. 271). Germinal centers appear in many of the follicles, and the surrounding stroma becomes densely infiltrated with the lymphoid cells. Individual follicles may develop, in the manner described, in any part of the gastrointestinal tract. The appendix especially is the seat of extensive lymphatic tissue formation. It is stated in the section on the lymphatic system that lymph glands may arise at any time in any region as the result of unusual conditions (p. 251), and this also holds true in the case of lymph follicles in the digestive tract.


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Reference

Bailey FR. and Miller AM. Text-Book of Embryology (1921) New York: William Wood and Co.



Cite this page: Hill, M.A. (2024, February 22) Embryology Bailey271.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Bailey271.jpg

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current23:01, 23 January 2011Thumbnail for version as of 23:01, 23 January 2011691 × 428 (72 KB)S8600021 (talk | contribs){{Template:Bailey 1921 Figures}} Category:Human Category:Gastrointestinal Tract Category:Liver