Histological and ultrastructural study on the juxtaglomerular apparatus in the kidney of the dromedary camel (camelus dromedarius)

The histology and ultrastructure of the different components of the juxtaglomerular apparatus (JGA) in the kidney of the dromedary camel (Camelus dromedarius) were described in the present study. Five samples selected randomly from the renal cortex of eight female adult dromedary camels were used for histology and ultrastructure. Results obtained showed that the macula densa (MD)cells were located at the terminal part of the cortical straight distal tubule and they were present either as single layer of cuboidal to columnar cells or as pseudostratified cells. MD cells rested on an irregular thick basement membrane and were characterized by strong PAS +ve stain, sparse collagen fibres and the lack of underlying reticular fibres. Numerous vesicles were often observed within this basement membrane whichwas characterized by a remarkable irregular arrangement. The most striking feature of the luminal surface of the MD cells was the presence of a single cilium. The MD cells were attached by gap junctions and the lateral surfaces of adjacent cells were separated by irregular intercellular spaces which were more prominent in the columnar type. The cytoplasm of the juxtaglomerular cells (JGCs) showed microfilaments and two types of cytoplasmic granules. The basal laminae of the JGCs, extraglomerular mesangeal cells (EMCs) and of the endothelial cells of the afferent arteriole near the JGCs appeared to have different types of vesicles. The cytoplasm of the EMCs was filled with spherical mitochondria, well developed rough endoplasmic reticulum and homogeneous granules.