Distribution of mucins in the abomasum and intestines of bovine fetuses during pregnancy

Aim: The aim of this thesis was to contribute to the understanding of organogenesis and cell differentiation by describing the histological development of the abomasum and lower digestive tract in bovine fetuses during gestation, and to reveal the histochemical and immunohistochemical characteristics of mucins (MUC2, MUC5AC and MUC6) in the secretions of epithelial and goblet cells and glands during the development of the abomasum and lower digestive tract. Materials and Methods: A total of 30 Holstein cow fetuses were used in this study. After the measurements, the abdominal region of the fetuses was opened and the stomachs and intestines were completely removed. Some of the sections were taken on normal slides for Crossmon's triple and histochemical staining. Some of the sections were transferred to slides coated with 3-ethoxysilane (APES) for immunohistochemical detection of MUCs and dried overnight at room temperature. Results: Parallel to the rotation of the rumen in the first period of gestation (63rd day of gestation), the abomasum was observed in a horizontal position on the left side just caudal to the fundus and reticulum and to the right of the omasum. In all three periods of gestation, finger-like mucosal protrusions of the duodenum, jejeunum and ileum mucosa towards the lumen, namely villi intestinalis, were observed. In both small and large intestine, mixed PAS (+) reactions were observed in the apical membranes and weak PAS (+) reactions were observed in the cytoplasm of prismatic epithelial cells covering the villi and crypts. It was noteworthy that MUC2 expression in the fetal abomasum showed a gradual increase as the pregnancy progressed. Conclusion: In this thesis, it was revealed that the morphological and histological development of the abomasum, small and large intestine of bovine fetuses during gestation was completed in the middle of the second period of pregnancy. It was revealed that neutral, sialo (COOH groups) and sulphated mucins and N-acetyl sialomucins were localized in the luminal and glandular epithelial cells and goblet cells in the abomasum, small and large intestine during gestation due to fetal development.