Histomorphological studies of the prenatal development of oesophagus of one humped camel (camelus dromedarius)

Abstract

A Histomorphological study was conducted on the oesophagus of 35 foetuses of the one-humped camel collected from the Sokoto metropolitan abattoir, over a period of five months at different gestational ages. The approximate age of the foetuses was estimated from the crown vertebral rump length (CVRL) and samples were categorised into first, second and third trimester. At the first trimester, only three layers were identified, ie; Tunica mucosa, Tunica muscularis and Tunica adventitia. At the second trimester, the orientation of fibres changed, resembling that of the adult with all the four layers prominent i.e. Tunica mucosa, Tunica sub-mucosa, Tunica muscularis and Tunica adventitia. At the third trimester, the Oesophageal gland appeared prominently in the tunica sub-mucosa resembling that of the adult camel. The Tunica mucosa epithelium was simple squamous epithelium at first trimester and began to change at second trimester to stratified squamous epithelium. At third trimester, the epithelium was keratinized stratified squamous epithelium with the oesophageal (sub-mucosal) glands appearing to be prominent and abundant. The tunica muscularis showed clearly a single layer at second trimester while at third trimester; both inner circular and outer longitudinal layers appeared. The tunica adventitia was typical. Blood vessels and nerve fibres became very visible at the tunica sub-mucosa and muscularis in third trimester fetuses. Based on the above findings, it showed that development of the camels’ oesophagus (based on embryonic stages) was morphological in succession. Presence of keretinised stratified squamous epithelium throughout the length of the oesophagus showed adaptive features of the animal to its environment and mode of feeding. Base on histological differentiation, camels’ oesophagus had little/few similarities with true ruminants embryologically.