The Relative Distribution of High Endothelial Venules in the Subepithelial Lymphoid Compartments of Human Palatine Tonsil

Objective: To study the distribution of high endothelial venules of lymphoid compartments of human palatine tonsils beneath the epithelium of the surface, mouth of the crypt and the crypt. Materials and Methods: This descriptive study was carried at the department of Anatomy, CPSP regional center, Islamabad, from January to July 2005.Thirty samples of palatine tonsils were collected by convenience sampling technique Haematoxylin and eosin stained paraffin sections were examined. The high endothelial venules in lymphoid compartments beneath the epithelial lining of surface and mouth of the crypt, and reticulated crypt epithelium were studied. Their number was counted and compared statistically. Results: The high endothelial venules found in the subepithelial compartments as well as within the reticulated crypt epithelium were characterized by prominent nuclei of the endothelial cells with non epithelial cells adherent on the luminal side. The mean count of high endothelial venules was 0.98 ± 0.12, 1.08 ± 0.12 and 2.07 ± 0.21 in the high power fields (under the oil immersion lens using 100X objective) beneath the surface, mouth of the crypt and reticulated crypt epithelium respectively. The difference between the former two was statistically insignificant (p=0.543). The number of high endothelial venules beneath the reticulated crypt epithelium was significantly more than the other two locations (p= 0.000 in each case). Conclusion: The high endothelial venules are distributed throughout the subepithelal compartments of human palatine tonsils. The number increases gradually yet insignificantly from the surface to the mouth of the crypt, whiles the lymphoid tissue beneath and within the reticulated crypt epithelium has significantly higher distribution of high endothelial venules than other subepithelial locations