Histogenesis of the metanephric duct system in goat

Abstract

Histogenesis of the duct system of metanephros was studied in goat embryos of different age groups ranging from 6 to 350 mm crown rump length (CRL). The primordium of duct system originated in the form of ureteric bud from caudal part of the mesonephric duct in embryos of 8 mm CRL (17 days). It divided into the cranial and caudal primary branches at ampullated end by 18 mm CRL (30 days). Each one of these redivided dichotomously in to secondary branches in embryos of 22 mm CRL (34 days). Subsequent branches (3rd, 4th and 5th orders) became evident by 35 mm CRL (46 days). These formed network of channels throughout the gland by 45 mm CRL (50 days) and arranged as medullary rays in embryos of 70 mm (56 days) to 120 mm CRL (74 days). The straight collecting ducts, coursed upward into the cortex and terminated finally as arched collecting ducts by 160 mm CRL (89 days) . The ducts of all orders showed cpithelial reaction for PAS-positive and Sudanophilic material in embryos of 180 mm CRL (96 days) and onwards. Their orientation and structure did not change further in embryos of subsequent ages except a gradual increase in staining intensity for PAS-positive and sudanophilic materials.