Strain Differences in Morphometrical Characteristics of Rat Kidneys

Abstract

ABSTRACT. To clarify the strain differences in the morphology of the rat kidneys, we investigated the morphometrical characteristics of the kidneys of Slc:Wistar, Slc:SD, and F344/NSlc rats. The diameter of the renal corpuscles in female F344/N rats is smaller than that in female Wistar rats. Although sex differences (males > females) were shown in SD and F344/N rats, no effects of castration were detected in any of the groups. Strain-dependent differences in the percentage of renal corpuscles with a cuboidal parietal layer were found in both male and female groups. The highest percentage of them was noted in male Wistar rats. Effects of castration were observed in female Wistar and male F344/N rats, and the values after castration were significantly higher than those in the intact animals. As for the number of proximal convoluted tubular nuclei, no strain differences were detected in either the male or female groups. Although a sex difference was found in SD rats (female>male), no effects of castration were detected in any of the groups. In female F344/N rats, numerous numbers of PAS-positive granules, which were observed in the proximal convoluted and straight tubular epithelia, were noted. Orchiectomy induced an increase of these granules in male SD and F344/N rats, but ovariectomy showed no effects on them in any strains. This is the first study to clarify the strain differences in the morphological characteristics of the kidneys in ordinary rat strains. KEY WORDS: castration, kidney, rat, sex difference, strain difference.J. Vet. Med. Sci. 68(11): 1185-1189, 2006 Rats are frequently used in animal experiments, and there have been many reports regarding the sex differences in the morphology and function of the rat kidneys; e.g., the segmentation of nephrons [13], the thickness of each of the renal zones [16], the ultrastructural features of the proximal tubular epithelium [21,27], the concentration and constituents of the urine [1,11,16], and the structural and functional alterations with aging [3,6,18,22]. The effects of castration and sex hormone-treatment in the rat kidneys have also been investigated, and the effects on the size of the glomeruli and proximal tubules [14], ultrastructural features of the proximal tubular epithelium [21,27], concentration and constituents of urine [11,16], and the severity of glomerular damage with aging or after uninephrectomy [3,5,15,19,20], have been reported. Regarding the strain differences, several reports demonstrated the strain differences in the urinary constituents [1], glomerular filtration rate (GFR) [7], renal plasma flow (RPF) [7], pathological changes with aging [6,18,22], and the sensitivity to nephrotoxicity due to chemical drugs [4,17] and high-protein food [12].Recently, we investigated the renal morphology in five mouse strains (ICR, BALB/cA, C3H/HeN, C57BL/6Cr and DBA/2Cr), and identified the sex and strain morphological differences; the percentage of the renal corpuscles exhibiting a cuboidal parietal layer (CPL), the diameter of the renal corpuscles,...

Morphological Characteristics of Renal Artery and Kidney in Rats

“…In previous studies, the sexual dimorphism of rat kidney morphology was demonstrated [32, 33]. In present study, it was shown that the male kidneys were heavier than those of the female.…”