The ultrastructure of the thin limbs of Henle in Kidneys of the desert heteromyid (Perognathus penicillatus)

Anatomical, histological and biochemical studies of desert rodent Gerbillus tarabuli (Thomas, 1902) kidney

The present work aimed to study the anatomy, histology, cytology and some biochemical parameters (urea, osmolality, haematocrit, serum natrium, serum kalium) of the kidney of Gerbillus tarabuli. The investigated animals (n = 16) were collected from the desert, weighed and transferred alive to the laboratory in separate cages. A blood sample was taken by puncture at the retro-orbital sinus of each animal using a Pasteur-type capillary pipette capillary. They were anaesthetized with urethane injection (25%), after which they were carefully dissected; their organs were taken out and prepared for the histological and cytological studies. Pasteur pipette capillary type the kidney of the Gerbillus tarabuli is subdivided into three regions: Cortex (1193.625±60μm), Outer Medulla (1316.72±73μm), Inner Medulla (2525.08±85 μm). Pasteur pipette capillary type the kidney of the Gerbillus tarabuli is subdivided into three regions: Cortex (1193.625±60μm), Outer Medulla (1316.72±73μm), Inner Medulla (2525.08±85 μm). The concentration of the biochemical parameters of urea (0.41 ± 0.02 g/L), osmolality (300.75 ± 3.33 mOs/kg), haematocrit (34.18 ± 1.3%), serum natrium (141.37 ± 2.31 mmol/L) and serum kalium (7.69 ± 0.39 mmol/L) is in the interval of the norm compared with several studies on desert and semi-desert rodents and also on the Wistar rat. These findings revealed the adaptive morphology and physiological function in the kidney of G. tarabuli to the desert environment.

Kidney morphology: update 1985

Many new observations have been made correlating changes in renal morphology with changes in renal function. These changes have led to a better definition of the various segments which make up the renal tubule. These morphological patterns vary in different species as is documented by morphologic studies and by differences in the patterns of enzymes in various nephron segments. The subdivision of cells located in the mesangial region of the glomerulus into several types may provide new areas to study with respect to disease processes.

Functional heterogeneity of the descending limbs of Henle's loop. I. Internephron heterogeneity in the hamster kidney

By using the in vitro microperfusion technique, were examined functions of the descending limbs of Henle's loop obtained from either the short-loop nephron (SDL) or the upper portion of the long-loop nephron of hamsters (LDLu). Morphological distinctions between these segments were confirmed by light and electron microscopic observations. Both segments were highly permeable to water. The LDLu was highly permeable to sodium and to chloride: efflux coefficients (10(-7) cm2 x s-1) for 22Na and 36Cl were 41.0 +/- 5.4 and 3.8 +/- 0.6, respectively. The SDL were less permeable to sodium and to chloride: efflux coefficient for 22Na and 36Cl were 2.9 +/- 1.4 and 0.9 +/- 0.2, respectively. In contrast, the SDL was more permeable to urea as compared to the LDL, efflux coefficients for urea being 5.1 +/- 1.4 vs 1.4 +/- 0.3, respectively. When composition of the perfusate was identical to that of the bathing fluid, no transepithelial voltage was demonstrated. The volume flux was very small or undetectable. From these observations, we propose that the internephron heterogeneity must be taken into consideration for constructing a model of countercurrent system in the renal medulla.

Functional heterogeneity of the descending limbs of Henle's loop. II. Interspecies differences among rabbits, rats, and hamsters

Permeability properties of the descending limbs of Henle's loop were compared among rabbits, hamsters, and rats by measuring transepithelial voltage (Vt) across the isolated renal tubules perfused in vitro. From the deflection of the Vt when the composition of the bathing fluid was varied, the permeabilities of sodium and of potassium relative to chloride (Pna/PCl and PK/PCl, respectively) were determined in either the descending limbs of the short-loop nephron (SDL) or the segments of the upper protion of the long-loop nephron (LDLu). In hamsters and rats, the values of PNa/PCl of the LDLu (3.98 +/- 0.66 and 5.03 +/- 0.79) were higher than those of the SDL (0.68 +/- 0.03 and 0.61 +/- 0.00). In contrast, in rabbits the value of PNa/PCl of the LDLu (0.96 +/- 0.05) was only slightly higher than that of the SDLu (0.75 +/- 0.03). The similar tendency was also noted in the values of PK/PCl. In hamsters and rats, the PK/PCi ratios were 4.90 +/- 0.82 and 6.44 +/- 0.90, respectively, in the LDLu and 1.09 +/- 0.04 and 1.02 +/- 0.0, respectively in the SDL. When a transepithelial osmotic gradient was imposed by adding raffinose to the bath, a lumen-negative streaming voltage of about -8 mV was generated in the hamster and the rat LDLu. Taken together with the findings in the preceding paper, these observations support the view that the descending limbs of rabbits are different from those of hamsters and rats in that internephron heterogeneity is less remarkable, and that the LDLu of hamsters and rats is highly permeable to sodium and to potassium as well as to water.

Histotopography and ultrastructure of the thin limbs of the loop of Henle in the hamster

In the kidney of the Syrian hamster the descending thin limbs of both the short and long loops of Henle are not spatially separated from each other and descend between the vascular bundles. Ultrastructurally, five different epithelial types are distinguished in the thin limbs of the short and long loops of Henle. Short loops possess only a descending thin limb with a simply organized epithelium (type 1). Long loops comprise an upper and a lower part of the descending thin limb and the ascending thin limb. The upper part of the long descending thin limb is equipped with a complex and highly interdigitating epithelium with shallow junctions (type 2), which gradually transforms into the simple noninterdigitating type-3 epithelium of the lower part. In a minor portion of long descending thin limbs, however, the upper part begins with an even more complexly organized epithelium (type 2a) than type 2. Type-2a epithelium is conspicuously thicker and possesses a more elaborate mode of cellular interdigitation. Along the descent of this tubular part through the inner stripe of the outer medulla, type-2a epithelium transforms into type-2 epithelium. It is suggested that the long descending thin limbs, which start with type-2a epithelium, belong to the longest loops. The type-4 epithelium of the ascending thin limbs is characterized by flat and extensively interdigitating cells with shallow junctions. The unique pattern of the type-2a epithelium favors the assumption that solute secretion essentially contributes to the increase in concentration of tubular fluid in long descending thin limbs.