Histomorphometric and immunohistochemical study of the goat rumen during prenatal development

This study sought to chart the ontogenesis of the goat rumen by histomorphometric examination, scanning electron microscopy and immunohistochemical analysis. A total of 140 goat 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 35 days of prenatal life (CRL 3 cm, 23% gestation). By 38 days (CRL 4.3 cm CRL, 25% 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 46 days (CRL 6 cm, 30% gestation), and by 76 days (CRL 18 cm, 50% gestation) ruminal papillae were starting to appear. Under scanning electron microscopy, by 50 days (CRL 7.7 cm, 33% gestation) small ruminal papillae were observed protruding from the surface. Finally, neuroendocrine cells (synaptophysin, SYP) were detected at 53 days (CRL 9 cm CRL, 35% gestation), while glial cell markers (glial fibrillary acidic protein--GFAP, and vimentin-VIM) were found at 108 days (CRL 31 cm, 72% gestation) and 39 days (CRL 4.4 cm, 26% gestation), respectively. Neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) were detected immunohistochemically at 113 days (CRL 33 cm, 75% gestation) and 120 days (CRL 35 cm, 80% gestation), respectively. In conclusion, histomorphogenesis of the rumen in goats was similar to that reported in deer, but rather slower than observed for sheep or cattle.