Histomorphology of lymphatic structure associated in intestine in Persian sturgeon (Acipenser persicus) in warm and cold seasons

Abstract

There have been numerous reports on histomorphology differences of the immune system during cold and warm seasons. A total of 10 Persian sturgeons (A. persicus) (healthy and with the same size) were captured from fish ponds in International Sturgeon Research Institute (ISRI) during winter (water temperature 7.30 °C) and summer (water temperature 27.90 °C). First of all, the biometric evaluation was performed and then 0.5 cm of anterior, middle, and posterior of intestine were trimmed and placed in formalin (10%) as a fixative solution. Then, samples were prepared using the standard histological technique and then tissue sections were cut (4-6 μm thick slices) and stained by H&E. The results showed that in intestine the intestine-associated lymphatic tissue presence in two different forms. First, the presence of lymphatic cells scattered throughout the epithelium and second, the presence of lymphatic cells inside the lamina propria and within submucosal. In the lamina propria, the lymphatic cells had a strip shape and their density increased towards the posterior part of the intestine. Results showed a significant difference in the number of lymphocyte cells in intestinal epithelial tissue between cold and warm seasons, and their density were more in the cold season compared to the warm season. There was no sex difference in the histomorphology of intestine-associated lymphatic tissue between cold and warm seasons. These tissues can play an important role in the immune system with the production of abundant lymphocytes especially in the cold season due to the more activity.