Cytochemical correlates of structural sexual dimorphism in glandular tissues of the mouse. I. Studies of the renal glomerular capsule

Rodent Renal Structure Differs among Species

In the present study, we histologically and morphometrically investigated species differences in renal structure using laboratory rodents (mice, gerbils, hamsters, rats, and guinea pigs). Morphometric parameters were as follows, 1) diameter of the cortical renal corpuscles, 2) diameter of the juxtamedullary renal corpuscles, 3) percentage of the renal corpuscles with a cuboidal parietal layer, 4) number of nuclei in proximal convoluted tubules (PCTs) per unit area of cortex, 5) semi-quantitative score of the periodic acid-Schiff (PAS) -positive granules in PCTs, and 6) semi-quantitative score of the PAS-positive granules in proximal straight tubules (PSTs). Significant species differences were detected for each parameter, and particularly severe differences were observed in the PAS-positive granules of PCTs and PSTs. Granular scores varied among species and sexes. Vacuolar structures that did not stain with PAS or hematoxylin-eosin were observed in the renal proximal tubules. The appearance and localization of these vacuolar structures differed remarkably between species and sexes.

Absence of Procarboxypeptidase R Induces Complement-Mediated Lethal Inflammation in Lipopolysaccharide-Primed Mice

Carboxypeptidase R (CPR) is a heat-labile enzyme found in serum in addition to stable carboxypeptidase N. CPR cleaves the C-terminal basic amino acids, arginine and lysine, from inflammatory peptides such as complement C3a and C5a, bradykinin, and enkephalin. This enzyme is generated from procarboxypeptidase R (proCPR), also known as thrombin-activatable fibrinolysis inhibitor, following cleavage by proteolytic enzymes such as thrombin, plasmin, and trypsin. We generated proCPR-deficient mice by knocking out exons 4 and 5 of the proCPR gene, which are regarded as essential for CPR function. At LPS challenge, there was virtually no difference in lethality among proCPR(+/+), proCPR(+/-), and proCPR(-/-) mice. However, challenge with cobra venom factor, which can activate and deplete almost all complement in vivo, induced a lethal effect on proCPR(-/-) mice following LPS sensitization which up-regulates C5a receptor expression. In contrast, proCPR(+/+) and proCPR(+/-) mice were able to tolerate the cobra venom factor challenge with the limited dose (30 U). Although carboxypeptidase N plays a role in inactivation of inflammatory peptides in vivo, CPR may also be important in the regulation of hyperinflammation.

Age-related morphological changes in kidneys of SPF C57BL/6Cr mice maintained under controlled conditions

Age-related morphological changes were examined in the kidneys of inbred C57BL/6Cr mice maintained in a controlled environment. The specific pathogen free status of animals used in the present study was confirmed by microbiological monitoring. Kidneys were histologically and histometrically investigated at 3, 5, 12, 15, 24 and 27-months-old. Kidney weights did not change with age. Renal corpuscles increased in number at 24- and 27-months-old, but diameter remained constant. The percentage of renal corpuscles with a cuboidal glomerular capsule decreased at 24- and 27-months-old. Score indicating glomerular damage increased from 5- to 27-months-old. Changes to the proximal convoluted tubules were severe. Vacuolar degeneration was observed from 12-months-old. Tubular atrophy was observed at 24- and 27-months-old, with number of nuclei per unit area increasing at the same ages. Amyloidosis and scar lesions were observed at 27-months-old. Focal cell infiltration around vessels was found at 24- and 27-months-old. Electron microscopy at 27-months-old revealed expansion of the mesangial matrices and fusion of foot processes in the glomeruli. Enlarged lysosomes with lipid content were observed in the proximal convoluted tubules.

Digital three-dimensional reconstruction and ultrastructure of the mouse proximal tubule

Mice are prime targets of experimental gene modification and have become object of an increasing number of biologic studies in renal physiology, development, and molecular biology. Phenotypic changes in response to gene modification require detailed information on normal structure. However, detailed analyses of normal mouse kidney structure and organization are lacking. This study describes the 3D organization and ultrastructural, segmental variation of the mouse kidney proximal tubule. A total of 160 proximal tubules in three C57/BL/6J mouse kidneys were analyzed on 800 serial sections from each kidney from the surface to the inner stripe of the outer zone of medulla. All tubules were reconstructed in 3D and visualized by interactive computer graphics. A quantitative ultrastructural analysis of the mouse proximal tubule at every 300 to 400 micro m was performed. The 3D representation revealed a distinct organization of the mouse proximal tubule, each occupying a separate domain within the cortex. Superficial proximal tubules have long straight parts converging into clusters within the medullary rays. Tubules originating deeper within the cortex become longer and increasingly tortuous. In the medullary rays, these are arranged in layers outside the clusters of more superficial tubules. In contrast to rat and human kidney, no major segmental variation in the ultrastructure of the proximal tubule was identified, and no parameters enabled definition of distinct segments in this strain of mice. In conclusion, significant new information on the 3D organization of the murine proximal tubule has been obtained. Quantitative, ultrastructural analyses of mouse proximal tubules reveal substantial differences compared with other species.

Life span and renal morphological characterization of the SAMP1//Ka mouse

The senescence-accelerated-mouse prone 1 (SAMP1) is considered to be a model of accelerated senility and it also develops severe kidney damage. The SAMP1//Ka mouse is a specific pathogen free (SPF) subline of SAMP1. The present study examined the life span of the SAMP1//Ka mouse and morphologically investigated the kidneys of this animal at 3, 4, 5, 9, 12, 15, 18 and 24 months of age. Males survived for an average of 25 months and females for 28 months. The median lifespan was 18 months for males and 20 for females. Focal cell infiltration and thickening of the basement membrane in the glomerular capsules or tubules appeared from 4 months of age. At 12 months old, glomerular lesions with expansion of the mesangial matrix and thickening of the basement membrane as well as scar lesions in the outer cortex appeared, and amyloid was deposited in the interstitium or glomeruli from 18 months of age. Morphometrically, although the area of the kidney sections was increased at 24 months of age, the diameter of the renal corpuscles, the number of nuclei of the proximal convoluted tubules and the percentage of renal corpuscles with a cuboidal glomerular capsule did not change with age. The results of the present study indicate that the life span of the SAMP1//Ka is increased and that their age-related renal changes differ from those of the original SAMP1.

Effects of estrous cycle on the mouse kidney morphology

Although mice kidney morphology shows various sexual dimorphisms, the effect of the estrous cycle has not previously been discussed. In this study, we investigated the effects of the estrous cycle on kidney morphology, including renin-positive areas, of female DBA/2 mice. No effects were confirmed in most of the histometrical parameters, however, the percentage of the renal corpuscles in which cuboidal epithelium covered under 50% of the parietal layer was significantly higher during estrus compared to that during anestrus.

Morphometrical analysis of sex and strain differences in the mouse nephron

In the present study, we investigated the sexual dimorphisms, effects of castration and sex hormone treatment, and strain differences in the morphology of mouse kidney by measuring the percentage of renal corpuscles with cuboidal cells in the parietal layer of the glomerular capsule, the diameter of renal corpuscles and the number of nuclei of epithelial cells in the proximal convoluted tubule. In ICR mice, the percentage of renal corpuscles with cuboidal cells and the diameter of renal corpuscles were larger in males than in females, and the numbers of nuclei were lower in males than in females. All of these parameters became similar to those of intact females by orchiectomy, and restored to levels similar to those in intact males after testosterone treatment to orchiectomized males. On the other hand, ovariectomy and estradiol treatment gave no effects to any of these parameters. Similar sexual dimorphisms were observed in BALB/c, C57BL/6, C3H/He and DBA/2 mice as in ICR mice, although the diameter of renal corpuscles was not significantly different between males and females in BALB/c mice. Strain differences were observed in each of these three parameters among the 5 strains. In conclusion, the present study demonstrated sexual dimorphisms, effects of castration and sex hormone treatment, and strain differences in the morphology of mouse kidney by morphometrical analysis.

Sexual dimorphism of proximal straight tubular cells in mouse kidney

The proximal straight tubular epithelium of the mouse kidney exhibited sexual dimorphism in conventional paraffin sections stained with periodic acid Schiff (PAS) in our preliminary observation. The purpose of this study was to clarify the sex-dependent structural features in the proximal straight tubular cells of the mouse kidney, and to clarify the effects of sex hormones on this portion of the renal tissue. The mice used in this study were divided into intact, orchiectomized, ovariectomized, testosterone-treated and estradiol-treated groups. The kidneys of these animals were examined by histological, cytological and cytochemical (for acid phosphatase reaction) procedures. In the proximal straight tubular epithelium of intact adult mice, PAS staining of the brush border in females was more intense than that in males. Furthermore, PAS-positive granules were observed in the cytoplasm of females only. Orchiectomy changed the male-specific features to that of the females, and treatment with testosterone induced the male-specific features. Ovariectomy and estradiol treatment showed no effects. Ultrastructurally, PAS-positive granules were observed as electron-dense myelinoid bodies, and these contained acid phosphatase-positive matrix. The present study demonstrated apparent sexual dimorphism and effects of testosterone on PAS staining and PAS-positive granules in the proximal straight tubule cells in normal mice. In addition, the association of PAS-positive granules and lysosomes was suggested by cytological and cytochemical examination.

Cytochemical correlates of structural sexual dimorphism in glandular tissues of the mouse

Circulating androgens are known to effect a sexual dimorphism of the submandibular gland and kidney of the mouse. Enzyme histocytochemical differences that correlate with these structural changes have been the subject of much study, especially in the kidney. In the present study, emphasis was placed on the hypogonadic effects of diabetes mellitus on the submandibular gland and kidney of C57Bl/KsJ db/db inbred mice with an autosomal recessive disease resembling maturity onset human diabetes mellitus. These glands of adult diabetic mice of both sexes were compared with those of unafflicted heterozygous littermates. The mitochondrial cytochrome oxidase and peroxisomal and cytoplasmic catalase were studied in their submandibular glands and kidneys. The parasympathetic innervation of the submandibular glands was studied by a histochemical method for acetylcholinesterase. The extensive differentiation of striated ducts of the submandibular gland into granular tubules in the postpubertal male mouse was readily evident with the cytochrome oxidase procedure. This differentiation resulted in ductal staining patterns characteristic of the sexes. Alteration of these patterns suggested that demasculinization or feminization was occuring in the male diabetic mice and that masculinization or virilization (defeminization) was occurring in the female diabetics. Similarly, in kidney, study of the parietal epithelium of Bowman's capsule revealed feminization in the male diabetics and masculinization in the female diabetics. With the catalase procedure, a dramatic sexual dimorphism was observed in the kidneys of the heterozygous unafflicted mice. Peroxisomal staining of epithelial cells of the proximal convoluted tubules was much more intense in the outer medulla of the male than of the female. In kidneys of the diabetics, the staining patterns again suggested that feminization of the male and masculinization of the female kidneys had occurred. On the other hand, neither a sexual dichotomy nor effects due to diabetes could be observed in the characteristic catalase staining observed in the luminal epithelial cells of submandibular gland distal ducts. The parasympathetic innervation of the submandibular gland, as revealed by the acetylcholinesterase method, was also markedly sexually dimorphic in the unafflicted mice. This was due to the more extensive innervation of the larger granular ducts characteristic of male than of the smaller striated ducts of the female. As a result of diabetes, the innervation and duct size decreased in the submandibular gland of the male, suggesting feminization, whereas they increased in the female suggesting masculinization. These changes were consistent with those observed in sumandibular gland with the cytochrome oxidase procedure. Attempts were made to interrelate all of the enzyme histochemical changes observed in submandibular gland and kidney with the weights of these glands, sex, gonadal weights, diabetic status and urinary protein excretion...

Osmiophilic reagents in electronmicroscopic histocytochemistry

Direct histocytochemical staining methods on undisrupted tissues, stabilized by chemical fixation, potentially offer perhaps the most reliable approach to the study of the enzymes of the cell with relation to its ultrastructure. The atoms which, for the most part, comprise the biomacromolecules and enzymes of cells and tissues contribute little to their inherent electron opacity or ability to scatter electrons differentially. The latter property of a substance is responsible for its observation with the electron microscope. Since the introduction of osmiophilic reagents into cytochemistry (HANKER et al. 1964), the selective deposition of relatively large amounts of polymeric osmium black reaction products at the subcellular sites of insoluble or immobilized enzymes or biomacromolecules has facilitated their demonstration with the light and electron microscopes. Perhaps the most widely employed osmiophilic reagent in histocytochemistry has been DAB which was introduced by GRAHAM and KARNOVSKY (1966a, b). Although it receives its widest use for demonstrating the sites to which the exogenous ultrastructural tracer horseradish peroxidase (HRP) is transported in vertebrate tissues, it is also widely employed for the demonstration of catalase in peroxisomes with the media of FAHIMI (1969) or of NOVIKOFF and GOLDFISCHER (1969), and for the demonstration of cytochrome oxidase with the medium of SELIGMAN et al. (1968a). The importance of this reagent lies in its ability to undergo oxidative polymerization forming an insoluble osmiophilic melanin-like product (HANKER et al. 1972a) which comforms well to ultrastructure, at the sites of enzymic or nonenzyme proteins which catalyze its oxidation. In the past few years, studies in our laboratory have shown that a rational approach to the histocytochemical demonstration of enzymes could be devised. It is based on the selective deposition of transition metal compounds at the sites of enzymes that resemble hemoproteins in their ability to catalyze the oxidative polymerization of DAB. The most useful of these compounds, cupric ferrocyanide (Hatchett's brown) was also introduced into cytochemistry by Karnovsky's laboratory (KARNOVSKY 1964; KARNOVSKY and ROOTS 1974). By the use of natural substrates, when available, or synthetic substrates which liberate or form a reducing agent at the sites of the enzymatic activity, many diverse types of enzymes have been demonstrated by methods depending on this principle known as catalytic osmiophilic polymer generation. DAB has probably been the most useful histocytochemical reagent of the past decade. Yet its borderline carcinogenicity and the frequent interruption of a supply of good quality DAB have encouraged research into a substitute reagent. A new substitute for DAB has resulted from the study of artificial melanins in our laboratory for several years. It consists of a mixture of p-phenylenediamine and pyrocatechol and is much better than DAB for the demonstration of HRP used as a cytochemical tracer...

Wafer embedding: specimen selction in electron microscopic cytochemistry with osmiophilic polymers

A new wafer embedding procedure is described that permits light microscopic screening of embedded tissue prior to ultrathin sectioning. It is particularly valuable when used on specimens obtained with an automatic sectioner and treated cytochemically to obtain visible intermediate or visible and electron opaque final reaction products. Aldehyde-fixed tissues are cut into sections with an automatic sectioner, incubated cytochemically osmication if required, then embedded in epoxy resin between fluorocarbon coverglasses which are supported by a platform specially designed for this purpose. The resultant wafter, less than 0.2 mm thick, is examined by light microscopy for optimal areas of cytochemical reaction and desirable structural features. Such areas are cut out and glued to blank blocks with fast curing cyanoacrylate cement for subsequent ultrathin sectioning. The usefulness of this technique is demonstrated by the location of: (1) esterase-positive lysosomes in kidney and trigeminal ganglia; (2) palatal sensory endings stained for acetylcholinesterase; and (3) phagosomes arising from the resorption of horseradish peroxidase tracer by the cuboidal parietal epithelial cells of Bowman's capsule in the male mouse.