Development and prevention of morphologic and ultrastructural changes in uremia-induced hyperplastic parathyroid gland.

The detailed ultrastructural changes of uremia-induced hyperplastic parathyroid gland and the effects of current medical treatments for secondary hyperparathyroidism were investigated. Marked enlargement of parathyroid cell with accumulation of mitochondria and lipids and a significant increase in the thickness of the pericapillary area with increased fibrosis and appearance of fibroblast like cells were noted in the hyperplastic gland caused by uremia and phosphate retention. These ultrastructural changes and biochemical findings indicating hyperparathyroidism were significantly suppressed by all of the treatment using phosphate restriction, calcitriol, and cinacalcet. The characteristic ultrastructural changes, including the morphologic evidence of nodule formation, were indicated.

Beneficial Effects of Cocoa in Perivascular Mato Cells of Cerebral Arterioles in SHR-SP (Izm) Rats.

As previously reported, the cerebral arterioles are surrounded by unique perivascular Mato cells. They contain many inclusion bodies rich in hydrolytic enzymes, and have strong uptake capacity. They are thus considered scavenger cells of vascular and neural tissues in steady-state. In this study, employing hypertensive SHR-SP (Izm) rats, the viability of Mato cells was investigated. In hypertensive rats, the capacity for uptake of horse radish peroxidase (HRP) and the activity of acid phosphatase (ACPase) of Mato cells were markedly reduced, and on electron-microscopic examination Mato cells were found to include heterogeneous contents and appeared electron-dense and degenerated. Vascular cells exhibited some signs of pathology. However, in hypertensive rats fed chow containing 0.25% cocoa, the uptake capacity and ACPase activity of Mato cells for HRP were enhanced, and on electron-microscopic examination Mato cells appeared healthy, with mitochondria with nearly normal profiles. Signs of pathology in vascular cells were also decreased. Superoxides may impair Mato cells and vascular cells.

[Study on the distribution of collagen fibers in the bifurcating area of cerebral arterioles of Wistar rats].

It was previously reported that Mato cells (Mato's fluorescent granular perithelial cells) were frequently localized in the bifurcating areas of cerebral arterioles and occasionally, collagen fibers appeared close to Mato cells of aged rats. It has also been established that Mato cells were scavenger cells in the cerebral tissue and provided with MHC-class II antigen. The present paper deals with the relationship between the distribution of collagen fibers and Mato cells in the bifurcating area of cerebral arterioles. 6 Wistar rats (3 rats aged 4 months and 3 rats aged 16 months) were employed for this electron microscopical study. They were perfused with the mixture of paraform-glutaraldehyde solution, and cerebral cortices were excised and fixed with 1% osmic solution and embedded in Epon 812. In order to observe the bifurcating area of cerebral arterioles, serial semithin sections cutting with the diamond knife were stained with toluidine blue, and checked under the light microscope. After obtaining available regions, serial thin sections were stained with uranyl acetate and lead nitrate, and observed with Hitach H7600 electron microscope. In order to survey the distribution of collagen fibers, 2 groups of the specimens of 4 months old (2 rats) and 5 groups of specimens of 16 months old rats (2 rats) were prepared. Each group consisted of serial 10 thin sections. Other rats of young and aged were used for complementary use. From the observation, it is confirmed that in the cerebral arteriole, collagen fibers are localized only in the interstices around Mato cells, and the fibers appear in a small quantity in the rats aged 4 months, while a certain amounts of the fibers are arranged sporadically in the rats aged 16 months. However, no collagen fibers can be detected in the subendothelial space and in the interstices among smooth muscle cells of cerebral arteriole. If Mato cells lack in some regions of cerebral arterioles, collagen fibers cannot be recognized. The following is also to be stressed that no fibroblastoid cells do appear in any serial sections of cerebral arterioles. From these findings, it seems possible that Mato cells play a principal role in the formation of collagen fibers in the cerebral arterioles, and associate with the sclerosis of cerebral arterioles.

[Study on the distribution of collagen fibers in the bifurcating area of cerebral arterioles of Wistar rats].

It was previously reported that Mato cells (Mato's fluorescent granular perithelial cells) were frequently localized in the bifurcating areas of cerebral arterioles and occasionally, collagen fibers appeared close to Mato cells of aged rats. It has also been established that Mato cells were scavenger cells in the cerebral tissue and provided with MHC-class II antigen. The present paper deals with the relationship between the distribution of collagen fibers and Mato cells in the bifurcating area of cerebral arterioles. 6 Wistar rats (3 rats aged 4 months and 3 rats aged 16 months) were employed for this electron microscopical study. They were perfused with the mixture of paraform-glutaraldehyde solution, and cerebral cortices were excised and fixed with 1% osmic solution and embedded in Epon 812. In order to observe the bifurcating area of cerebral arterioles, serial semithin sections cutting with the diamond knife were stained with toluidine blue, and checked under the light microscope. After obtaining available regions, serial thin sections were stained with uranyl acetate and lead nitrate, and observed with Hitach H7600 electron microscope. In order to survey the distribution of collagen fibers, 2 groups of the specimens of 4 months old (2 rats) and 5 groups of specimens of 16 months old rats (2 rats) were prepared. Each group consisted of serial 10 thin sections. Other rats of young and aged were used for complementary use. From the observation, it is confirmed that in the cerebral arteriole, collagen fibers are localized only in the interstices around Mato cells, and the fibers appear in a small quantity in the rats aged 4 months, while a certain amounts of the fibers are arranged sporadically in the rats aged 16 months. However, no collagen fibers can be detected in the subendothelial space and in the interstices among smooth muscle cells of cerebral arteriole. If Mato cells lack in some regions of cerebral arterioles, collagen fibers cannot be recognized. The following is also to be stressed that no fibroblastoid cells do appear in any serial sections of cerebral arterioles. From these findings, it seems possible that Mato cells play a principal role in the formation of collagen fibers in the cerebral arterioles, and associate with the sclerosis of cerebral arterioles.

In vitro characterization of Mato's FGP cells isolated from rat cerebrum.

Mato's FGP cells surrounding cerebral arterioles play a significant role in the maintenance of a homeostatic microenvironment in the brain. In this study, the perivascular cells were isolated from rat cerebral microvessels and cultured in vitro to characterize their phenotype. Autofluorescence of the intracellular granules in cultured cells and the uptake of HRP and DiI-Ac-LDL by these cells were observed. The cells reacted positively to an anti-scavenger receptor A antibody. Positive immunoreactions of cultured cells to ED1 and ED2 antibodies were observed, whereas they were weak or negative to ED3 and OX42 antibodies. Acid phosphatase activity was detected in the granules of cultured cells. In conclusion, the cells cultivated under the present conditions revealed very similar characteristics to Mato's FGP cells in situ and therefore are useful for studies on FGP cells.

Inclusions in novel perivascular macrophages (Mato's fluorescent granular perithelial cells) and neurons in the cerebral cortex of Hex A- and Hex B-deficient mice.

Beta-hexosaminidases are important enzymes for lipid and saccharide metabolism in the brain. In mice deficient in these enzymes, indigestible metabolic intermediates deposit in neurons. Inclusions such as membranous cytoplasmic bodies (MCB) and zebra bodies were seen in neurons of Tay-Sachs (TS) model mice, Sandhoff's disease (SD) model mice, and double knockout (DKO) mice. However, the cerebral perivascular macrophages discovered by Mato are active in the uptake of waste products and regarded as scavenger cells under steady-state conditions. We observed that indigestible components derived from neurons were taken up by the perivascular macrophages of TS mice by pinocytosis, but those of SD and DKO mice contained only pale inclusions and had marked vacuolations, and pinocytosis was rarely observed. Histochemically, the inclusions in the perivascular macrophages of TS mice were positive for the PAS stain, but those of SD and DKO mice were negative. In addition, the perivascular cells of TS mice expressed clear positive immunoreactivity against BM-8 and F4/80, but those of DKO mice had very weak BM-8 and F4/80 immunoreactivity. These differences between TS, SD, and DKO mice are based on their metabolism of oligosaccharides and glycosaminoglycans (GAG). Thus, hexosaminidase B is more important for keeping normal morphology and function of perivascular macrophages than hexosaminidase A. The foamy cells that appeared along the cerebral microvessels in lipidosis and saccharidosis were identified as perivascular macrophages (Mato's fluorescent granular perithelial cells: FGP cells).