The morphological and functional differentiation of the alimentary canal of the pig during ontogeny. I. Development and differentiation of the fundic portion of the stomach

Abstract

Several periods of intensive growth are observed in the development of the fundus of pig's stomach: at the end of the 2nd and the beginning of the 3rd month of embryogenesis, the periods shortly prior to and after birth, and between the 10th and 20th day following birth. The gastric pits are formed at about the 45th day of embriogenesis. At the beginning of the third month the fundic glands are formed. The parietal cells first differentiate and are found in 60-day old embryos. The mucous neck cells are differentiated at the beginning of the 3rd month but secretion of mucoid substance starts on about the 45th to 50th day of the prenatal development. With increasing age of the pigs the quantity of PAS-positive substances in the surface epithelium, as well as in the mucous neck cells gradually increases. The differentiation of the chief cells rich in RNA occurs approximately on the 90th day of the prenatal development.