Histological development of bovine abomasum.

The histological development of the bovine abomasum during fetal and neonatal periods was studied. The abomasum in a fetus of 2.3 cm in length (estimated to be 1 month old) was a separated compartment situated to be caudo-ventral to the primordium on the median plane. On the later stages, the primitive stomach became distinctly separated into rumen, reticulum, omasum and abomasum. The epithelium of abomasum was pseudostratified histologically, consisting of cells low differentiation. The stomach in a fetus of 13-14 cm in length (estimated to be 3 months old) displayed the morphological feature with nearly same proportion as an adult stomach. In this stage, abomasal epithelium had a shape of simple column and also formed gastric pits. Pyloric gland cells could be recognized earliest of all the gastric exocrine cells in fetuses of 16-18 cm in length (estimated to be 3-4 months old). Mucous neck cells could be found in fetuses 43-45 cm in length (estimated to be 5-6 months old). Pyloric gland cell and mucous neck cell contained neutral and sialo- or sulfo mucosubstances in neonates. Chief cells, could be noticed in fetuses 58-65 cm in length (estimated to be 6-7 months old), and were devoid of demonstrable mucosubstance as well as parietal cells. Main abomasal gland cells began to develop to increase rapidly in number in the latter half period of gestation. All the types of gastric cells became to be present and mature in form at birth.