Prenatal histomorphological development of the rumen in Dama dama

Abstract

This work studies the morphological changes taking place in the Dama dama rumen during prenatal development using histomorphometrics, surface microstructure and immunohistochemistry analysis as well as carrying out a comparative analysis of this species with other wild (red deer) and domestic-type ruminants. A total of 25 fallow deer embryos and fetuses were used, from the first stage of prenatal life until birth. The appearance of the rumen from the primitive gastric tube was observed at 51 days of prenatal life (CRL 3 cm, 21% gestation). By 57 days (CRL 4.3 cm, 24% gestation) the ruminal wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Ruminal pillars were visible at 72 days (CRL 6 cm, 30% gestation), and by 85 days (CRL 7.2 cm, 35% gestation) ruminal papillae were starting to appear. Under scanning electron microscopy, by 80 days (CRL 7 cm, 33% gestation) small ruminal papillae were observed protruding from the surface. Morphometric results showed accelerated growth of the epithelial layer and the tunica muscularis at 180 days (75% gestation). By contrast, the growth-rate of the lamina propria and submucosa declined from the early embryonic stages until birth. The serosa maintained a steady rate of growth until birth. Neuroendocrine cells (synaptophysin) were detected at 85 days (CRL 7.2 cm CRL, 35% gestation), while glial cell markers (glial fibrillary acidic protein and vimentin) were found at 108 days (CRL 31 cm, 45% gestation) and 63 days (CRL 4.4 cm, 26% gestation) respectively. Neuropeptide Y and vasoactive intestinal polypeptide were detected immunohistochemically at 180 days (CRL 33 cm, 75% gestation) and 192 days (CRL 35 cm, 80% gestation) respectively. In comparison to other wild and domestic-type ruminants, histomorphogenesis of the rumen in Dama dama was similar to that reported in red deer and goats, but rather slower than that observed for sheep or cattle.