The distribution of four homeobox proteins in the bovine stomach compartments during the fetal period

Homeobox proteins undertake important roles in the determination of the cell identity during embryonic development, the differentiation of embryonic stem cells, morphogenesis, and the formation and development of the mammalian gastrointestinal tract. Based on these data, this study was designed to determine the immunohistochemical localization and expression levels of HOXA10, HOXA11, HOXC6 and HOXB6, which are subunits of the homeobox proteins, in the rumen, reticulum, omasum and abomasum during fetal development. For this purpose, fetuses obtained from private slaughterhouses and were grouped according to their crown-rump length (CRL) measurements, and the gestational trimester they belonged to, as follows: first trimester (69-89 days old/10 fetuses), second trimester (99-178 days old/10 fetuses) and third trimester (188-269 days old/10 fetuses). Gastric tissue samples taken from each group underwent routine histological processing and immunohistochemical staining. Immunohistochemical staining demonstrated that the HOXA10, HOXA11 and HOXC6 proteins were expressed at varying levels in the rumen, reticulum, omasum and abomasum, and their expression was stronger in the epithelial and smooth muscle cells. On the other hand, while there was almost no expression of HOXB6 in the epithelial cells of the rumen during the second and third trimesters of gestation, the remaining gastric components were immunonegative. Based on these findings, it was concluded that some homeobox proteins could have critical roles in the development, morphogenesis and histogenesis of fetal bovine gastric compartments, and thus, could contribute to the lifetime performance and productivity of cattle in terms of milk and meat yields.