生物学と医学

概要

Embryonic Diffrentiation of the Colon of One Humped Camel (Camelus Dromedarius): A Histomorphology

Bello A, Onyeanusi BI, Sonfada ML, Umaru MA, Onu JE, Hena SA, Danmaigoro A, Oyelowo FO, Baraya YS, Onimisi BO and Aliyu A

A study involving histomorphological differentiation was conducted on the colon of 35 foetuses (both sex) 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 fetuses was estimated and categorized into first, second and third trimester. Grossly, the color of the large intestine was whitish at first trimester and grayish to white in second and third trimester. The colon was divided into three main portions namely the ascending colon, the coiled and the descending part which formed the long part of the colon in second and third trimesters. At first trimester the coiled part was not differentiated but divided into two parts such as the centripetal and centrifugal part at second and third trimester. Histological observation of the tissues in this study revealed a complete structure of the tubular organ. The colon was found to consist of four layers namely: Tunica mucosa, Tunica sub mucosa, Tunica muscularis and Tunica serosa. The epithelium of the Tunica mucosa was stratified squamous epithelium with varying degree of stratification at first trimester and transformed to low columnar /cuboidal epithelium at second trimester. At third trimester, the epithelium was simple columnar epithelium. The lamina propria mucosa was found absent at first trimester but prominent at second and third trimester. The Lamina muscularis mucosa was found prominent at third trimester but not identified at first and second trimester. At first trimester of age tunica submucosa was prominent while at second trimester, it consisted of connective tissue cells and fibres scattered all over the layers with preliminary blood vessels. The cells and fibres were undifferentiated at this stage. There was no evidence of lymphatic nodular cells within the layer. At third trimester of age, the connective tissues and blood vessels were found prominent and the lymphatic nodular cells were found throughout the length of the colon. The tunica muscularis of camel colon consist of inner skeletal and outer longitudinal smooth muscle layers. At first trimester this layer did not differentiate into these two zones but only longitudinal orientation of smooth muscle layer. At second trimester, the layers of two zones with clear demarcation were observed. A thin layer of connective tissue comprising of undifferentiated cells lined the colon externally was observed in all the stages of development. Based on the above findings, it showed that development of the camels’ colon was histologically in succession and different from other domestic animals by having an extensive skeletal muscle at the tunica muscularis.