Histological studies of kidney in Emu (Dromaius novaehollandiae)*

Abstract

Histological studies of kidneys of adult Emu revealed a thin capsule which was closely adherent to the underlying tissue and the parenchyma consisted of large polyhedral cortical lobules and smaller medullary lobules. Former was a labyrinth of tubules and nephrons whereas renal medulla comprised of several converging medullary lobules populated with loops of Henle, distal tubules and collecting ducts in wide expanse of connective tissue.. Two types of nephrons viz., reptilian type (close to surface and in mid cortical region) and mammalian type (close to juxta medullary and deep cortical regions) were observed in renal parenchyma. Both types featured all parts such as macula densa and juxtaglomerular (JG) apparatus. Proximal tubules with narrow lumen were lined by tall cuboidal cells with brush border whereas distal tubules were smaller and lined by low cuboidal cells. Thick and thin limbs of Henle lined by cuboidal cells and either low cuboidal or flattened cells were seen in medullary lobules respectively. Several collecting tubules joined to form secondary branches which in turn emptied into two primary branches of ureter in medulla.