File:Bailey271.jpg

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.

Text-Book of Embryology: Germ cells | Maturation | Fertilization | Amphioxus | Frog | Chick | Mammalian | External body form | Connective tissues and skeletal | Vascular | Muscular | Alimentary tube and organs | Respiratory | Coelom, Diaphragm and Mesenteries | Urogenital | Integumentary | Nervous System | Special Sense | Foetal Membranes | Teratogenesis | Gallery of All Figures

Historic Disclaimer - information about historic embryology pages

Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Reference

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

Cite this page: Hill, M.A. (2024, April 25) Embryology Bailey271.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Bailey271.jpg

What Links Here?

© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G