The histogenesis of the ruminal mucosa was studied in 9 buffalo fetuses (CRL 90--730 mm) and one suckling female buffalo calf. The Lamina epithelialis was found to consist of a basal and superficial layer. The former consists firstly of 2--4 cell layers and becomes later reduced to only one, made up to columnar cells; the latter one consists firstly of about 9 cell layers and increases then to 28--35, depending on the ruminal compartment. The epithelium shows its embryological feature, i.e. all nuclei are directed to the luminal cell pole. The first incidence of the ruminal papillary formation in the Egyptian water buffalo is observed in fetuses of 170 mm CRL. The histogenetic steps of the formation of the ruminal papillae are the aggregation of the cells of the basal layer and of the Lamina propria; the undulations with involvement of the basal layer of the Lamina epithelialis, basement membrane and Lamina propria; formation of humps from the undulations; formation of papillae. The papillary primordia are seen first in the Atrium ruminis and in the caudoventral blind sac simultaneously. The suckling calf has still no definite ruminal papillae. Only their tips are projecting to a different extent into the lumen.