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. Anat Rec, 295:776-785, 2012. V C 2012 Wiley Periodicals, Inc.Key words: Capra hircus; forestomach; histochemistry; histology; prenatal developmentThe goat is among the ruminant species best able to make use of marginal pasturelands (Boyazoglu et al., 2005;Rancourt et al., 2006), and is highly adapted to grazing over a wide range of vegetation (El-Gendy et al., 2010). Browse appears to be an important component of its diet, and it is widely regarded as the best user of poor roughage (Gihad et al., 1980). Morphological analysis of the goat digestive tract has led to its being classed as an intermediate feeder, situated between the concentrate selectors at one extreme and the grass-roughage eaters at the other (Hofmann 1973(Hofmann , 1989.This ability to make use of grazing land is linked to the particular morphology of the ruminant stomach, which comprises four compartments: rumen, reticulum, omasum, and abomasum. The rumen, reticulum and omasum form the forestomach (proventriculus), whose tunica mucosa is lined by a squamous, keratinized stratified epithelium (Ramkrishna and Tiwari, 1979;