Equine Stomach Development in the Foetal Period of Prenatal Life—An Immunohistochemical Study

SIMPLE SUMMARY: The endocrine cells of the alimentary tract (APUD) are an important component of the mucosa structure and significantly influence the stomach and intestine physiology. Prenatal development of the stomach is not limited to the qualitative and quantitative changes observed in the gastric wall, but is also reflected in APUD cell occurrence and their potential function in the development and maturation of the organ. Moreover, the perinatal period, crucial for the colostral globulin intake by the new-born animal, requires an adequately prepared gastric mucosa and its excretory function must be controlled. This study was aimed at immunohistochemical changes observed in the foetal period in equine foetuses. The changes were related to the reactivity of the endocrine cells and allowed us to better understand the developmental processes taking place both in the prenatal and perinatal period. ABSTRACT: The study consisted of the immunohistochemical analysis of fundic and pyloric mucosa in the equine stomach between the 4th and 11th month of gestation. The accessible material was classified into three age groups using the CRL method. The adult reference group was used to define potential differences between foetal and adult populations of gastric APUD cells. The samples were preserved, prepared, and stained according to the standard protocols. The immunohistochemical reaction was assessed using the semi-quantitative IRS method. The results were documented and statistically analysed. The most significant increase was seen in gastrin (G) cell activity. The activity of other endocrine cells (cholecystokinin (I) cells, somatostatin (D) cells, and somatotropin receptor (SR) cells) was less dynamic. This study proved that the development of APUD cells within the stomach mucosa undergoes quantitative and qualitative changes during stomach development. Our results correspond with the findings described in the accessible literature and prove a strong correlation between morphological changes in the stomach wall and the organ development, growth, and maturation.