الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
This work was carried out to investigate the structure of the camel’s kidney and its accommodation with the surrounding hard environment of the desert. This investigation was done on 6 kidneys of adult one-humped male camels (Camelus dromedarius) of apparently healthy ones with 7-9 years old. Each samples was examined by both light and electron microscopy (TEM and SEM). Light microscopical samples were taken from 7 pieces of each kidney. Electron microscopical samples were taken from both cortex and medulla of each kidney.
The obtained results revealed the following:
Capsule and interstitial tissue
The capsule of camel’s kidney is thick consisting of two layers, the outer one is very thick and the inner one is much thinner. The cortical and medullary interstitium are characterized by presence of intertubular cells with two main types, fibroblast and mononuclear cell.
Renal corpuscle
The renal corpuscles are mainly spherical in shape. The parietal layer of Bowman’s capsule is lined by simple squamous epithelium which sometimes possesses a single cilium extending into the Bowman’s space and also some short microvilli. These squamous cells rest on a very thick basal lamina which contains vacuoles and very electron dense granules.
The visceral layer of Bowman’s capsule consists of podocytes which are stellate in shape with a complex branching consisting of primary, secondary and tertiary processes. The terminal processes called pedicles which interdigitate with each others and with pedicles of other cell. Microprojections are commonly found on the free surface of podocytes.
The cytoplasm of podocyte is mainly electron lucent with cisternae of rough endoplasmic reticulum, mitochondria, polyribosomes and a fine mesh of tonofilaments and cytoplasmic plaques. The pedicles rest on a thickened basal lamina. The filtration unit of camel’s renal corpuscle consists of the fenestrated capillary endothelium, basal lamina, and slit diaphragm. The glomerular basement membrane consists of three layers, thick central electron dense layer (lamina densa) and narrow less denser layer on either side, the lamina rara externa and lamina rara interna. The lamina densa contains scattered electron dense granules with a very small size.
The mesangial cells are star shaped with long cytoplasmic processes. The cytoplasm is electron dense containing lysosomes, ribosomes, polyribosomes and endoplasmic reticulum. The cytoplasmic processes contain large vacuoles, fine filaments and plaques.
Proximal tubule
The proximal tubule is lined by truncated pyramidal cells, with large, spherical nuclei, centrally located. There is extensive lateral interdigitation and basal infoldings containing elongated mitochondria with long tubular cristae.
The lumina border is covered by numerous long microvilli. The cytoplasm is characterized by the presence of prominent endocytotic apparatus with four components. The cells lie on a very thick basal lamina containing membrane bounded bodies.
Loop of Henle
The cells of thin limb of loop of Henle are flattened with stubby microvilli sparsely distributed on the cell surface. The cytoplasm contains very few organelles. The nuclei are flattened or oval shaped and may bulge into the lumen. The cells rest on a very thick basal lamina which exhibit a multilayered appearance and contains membrane bounded bodies at various levels surrounded by a clear hallo of basal lamina.
Distal tubule
The lining cells of the distal tubule are cuboidal with spherical or oval nuclei apically located. The cells do not have a brush border but there are few laminal stubby microvilli. These are extensive interdigitations between the cells which extend from the lumen to the basal region. Lateral interdigitations and deep basal infoldings both carry elongated mitochondria. The cytoplasm contains numerous mitochondria, polyribosomes, lysosomes, superficial tonofilaments and ill developed endocytotic apparatus.
The cells rest on a very thick basal lamina with electron dense membrane bounded bodies. The juxtamedullary cells in the wall of the afferent arterioles have a number of membrane bounded secretory granules containing renin hormone.
Collecting tubule
There are two types of cells lining the collecting tubule. The first type is light cells with a single central cilium and some sparsely distributed microvilli. The cell is nearly cuboidal with large spherical nucleus, centrally located. The cytoplasm is electron lucent with multiple randomly oriented elongated mitochondria with tubular cristae. There are basal infoldings. The second type is dark cells and they are less numerous than the light ones. This type has thin folds or microplicae on the free surface and possess no cilia. They are found in between the light cells. The cytoplasm is electron dense. The nucleus is large, central and spherical. The cytoplasm contains more mitochondria which located mainly around the nucleus and in the apical cytoplasm. There are also abundant rough endoplasmic reticulum and few polyribosomes in the cytoplasm. Cells of the medullary collecting tubules are taller than the cortical ones.
The basal lamina of the collecting tubule is not very thick like other parts of the tubules. There are numerous collagen fibrils which are denser than those of other parts of the tubules.
Renal pelvis
The wall of the renal pelvis is lined by transitional epithelium with few microvilli. Some cells may have a single cilium. The secondary folds originating from the pelvis wall formed a core of dense collagen fibers with blood vessels and nerves and covered by transitional epithelium.