A Bello, DI Dabai, MA Umaru, SA Shehu and MI Jimoh
Histomorphometric study was conducted on the kidneyof seventeen (17) fetuses of the Yankasa sheep (Ovis aries) collected from the Sokoto metropolitan abattoir, over a period of one month at different gestational ages. The approximate age of the fetuses was estimated from the crown vertebral rump length (CVRL) and samples were categorised into first, second and third trimester. Out of the seventeen (17) fetuses at different gestational age used for the study, 7 (48%) were females while 10 (52%) were males. 6(35%) fetuses belong to first trimester, 5(30%) belong to second trimester and 6(35%) belong to third trimesters of pregnancy respectively. The mean crown vertebrate-rump length (CVRL) ranged from 12.47 ± 1.80 cm at first trimester to 33.79 ±1.52 cm at third trimester. Histological observation shows that the kidney appeared to have two zones via cortex and medulla right from first to third trimester. The development of renal tissues were found to be in succession, from the stage of mesenchyme cells, developing glomerulusand finally to fully developed glomerulus with advancement of gestational age among the three groups. The duct system also followed the same trend of development from immature to matured duct system. The cortex of the first trimester kidney was found to have numerous mesenchymal cells and connective tissues with few developing glomerulus. At second trimester few fully developed glomerulus were found, moderate number of mesenchyme cells and immature developing duct system. Numerous developed glomerulus and matured duct system with moderate developing glomerulus and connective tissue were seen at third trimester. The medulla at first trimester shows only various types of connective tissue (collagen, reticular and elastic) fibers and mesenchyme cells. At second trimester the medulla was found to have numerous developing collecting ducts, few developed collecting ducts and few mesenchyme cells. Developed collecting ducts were predominant in the medulla at third trimester with few mesenchyme cells. The histological differentiation of the Yankasa sheep kidney is similar to that of ovine, bovine, equine, Llama, and guanaco but differs from that of the feline, canine and porcine. Meanwhile, considering the histological features observed in the study, the Yankasa sheep kidney may become fully matured and functional at post-natal age.