Osamu Koide

Cell death and regeneration of renal proximal tubular cells in rats with subchronic cadmium intoxication

Male Sprague-Dawley rats were injected subcutaneously with 0.6 mg cadmium (Cd)/kg/day for 8 wk. The subsequent changes in renal proximal tubules were studied histologically, histochemically, and ultrastructurally. The urinary and tissue Cd concentrations were determined by atomic absorption spectrophotometry. After 4 wk of exposure, apoptosis was observed predominantly in segment S3 along with epithelial regeneration in the affected tubules, and these changes gradually became more pronounced as the experimental period was prolonged. The apoptotic cells were shed into the lumen and were found to contain a large quantity of Cd. Apoptotic cells were counted in paraffin sections after various periods of exposure to Cd. Nuclear bromodeoxyuridine uptake, mitotic count, and nuclear density were used as indicators of tubular regeneration. A correlation was found between the numerical increase of apoptotic cells and the rate of urinary Cd excretion, and the rate of increase in the tissue Cd concentration had a tendency to reduce after 4 wk as the rate of urinary Cd increased. These observations suggest that apoptosis might be helpful for the efficient excretion of Cd into urine. Progressive increases in the preceding indicators of regeneration were observed. From our results, it appears that Cd-induced tubular damage, i.e., cell deletion due to apoptosis, is reversible as a result of marked epithelial regeneration. On the basis of these histological changes, the critical concentration of Cd required to produce renal tubular damage was estimated to be 600 μg/g dry tissue.

Pathological Study on Beagles after Long-term Oral Administration of Cadmium*

Histopathological, histochemical, and electron microscopic examinations were performed on beagles after a long-term oral cadmium (Cd) administration of > 8 years. Although renal atrophy was remarkable in groups receiving doses of 50 and 100 mg/kg body weight/day, bone lesions could not be demonstrated by roent-genological and histopathologic examination. It was noticed that concomitant regeneration or recovery and cell death of the epithelium occurred in the proximal convoluted tubules. The cell death was consistent with apoptosis, a special feature of cell death, which was shown to play a major part in the tubular damage of cadmium by electron microscopic examination. Fatty degeneration of the pars recta tubules was seen to show dose-dependence. The intrarenal cadmium was localized predominantly in the cytoplasm of the proximal tubular epithelium by histochemical and ultraccntrifugal cell fractionation examinations. Although no remarkable changes were found in the other organs, aggregates of siderophages in the liver and focal hemorrhage in the spleen, known as spontaneous lesions, might be related to Cd intoxication. In conclusion, the present study revealed that no bone lesions occur with Cd administration in adult beagles in spite of long-term administration. An excessive cell death to regeneration or recovery in the proximal tubules might result in the renal cortical atrophy. No remarkable changes were seen in the glomeruli and distal nephrons, which were in good agreement with Cd distribution.

Identification of testicular atypical germ cells by an immunohistochemical technique for placental alkaline phosphatase

The identification of atypical testicular germ cells is often difficult by routine histologic examination. By immunohistochemical detection of placental alkaline phosphatase (PLAP) and by periodic acid Schiff staining of glycogen, atypical germ cells were easily identified in testicular samples. Forty‐one fetal and adult testes were used for a preliminary study, and 121 testes from infants and adults with either cryptorchidism or germ cell tumors were studied for the presence of atypical germ cells. Two types of clear germ cells were differentiated histochemically, and one with PLAP‐positive cell surfaces and glycogen‐rich cytoplasm was considered to be atypical. The alkaline phosphatase of atypical germ cells appeared to be similar to that found in a few germ cells of early fetal testes. The atypical germ cells seemed to be multi‐potential malignant cells capable of developing not only into seminoma but also into other germ cell tumors. Only in yolk sac tumor of infants were the atypical germ cells absent from tumor‐adjacent seminiferous tubules.

Dose dependent effects of inhaled ethylene oxide on spermatogenesis in rats.

Male Wistar rats were exposed to ethylene oxide (EO) at concentrations of 50, 100, or 250 ppm for six hours a day, on five days a week for 13 weeks. Dose effect relations of inhaled EO on spermatogenesis were evaluated from testicular and epididymal weights, histopathological changes and lactate dehydrogenase X (LDH X) activity in the testis, and sperm counts and sperm head abnormalities in the epididymis. At 250 ppm, a decrease in epididymal weights, slight degenerations in the seminiferous tubules, decreased sperm counts, and increased numbers of abnormal sperm heads in the tail of the epididymis were found; these were not seen at lower doses. When the abnormal sperm heads were classified into immature types and teratic types, the number of immature heads increased only at 250 ppm. On the other hand, the teratic type had increased at doses of 50 and 100 ppm EO when compared with the control group. Hence, subchronic inhalation of EO at low concentrations affects spermatogenesis in rats.

Preventive effects of methylcobalamin on the testicular damage induced by ethylene oxide

In this study, the effects of methylcobalamin on testicular damage induced by ethylene oxide (EtO) were studied. When Wistar male rats inhaled EtO at 500 ppm, 6 h a day, 3 days a week, for 6 weeks, testicular damage was observed histopathologically and by some other parameters. Subcutaneous injection of methylcobalamin at 500 μg/kg, 5 times/week was found to ameliorate the damage. However, the degree of the methylcobalamin effect differed among the parameters examined in this study. Decrease in testicular weight due to EtO exposure was completely prevented by methylcobalamin, and decrease in testicular mature spermatid count and LDH-X activity was fairly well prevented. The degree of prevention of alteration in the epididymis, such as epididymal weight, epididymal sperm count and sperm abnormality rate, was significant but not complete. EtO caused apparent alterations in glutathione metabolism in the testes, but methylcobalamin did not affect such alterations induced by EtO. From these results, it has been determined that methylcobalamin has definite preventive effects on testicular toxicity of EtO.

Effects of megadoses of pyridoxine on spermatogenesis and male reproductive organs in rats

Although it has been indicated that many neurotoxicants also cause reproductive toxicity, the reproductive toxicity of megadoses of pyridoxine, which is a neurotoxicant, has not been studied. In this paper, we studied the effects of megadoses of pyridoxine on male reproductive organs. Pyridoxine hydrochloride, 125 mg/kg, 250 mg/kg, 500 mg/kg or 1000 mg/kg, daily, was intraperitoneally injected into Wistar male rats 5 days a week for 2 or 6 weeks, and its effects on the male reproductive organs were investigated. After 2 weeks of administration, absolute weights of the testis in the 500 and 1000 mg/kg epididymis in all the exposed groups and prostate gland in the 1000 mg/kg group decreased, and mature spermatid counts in the testis decreased in the 1000 mg/kg group. After 6 weeks administration, the absolute and relative weights of the testis, epididymis, prostate gland and seminal vesicle decreased in the 500 mg/kg and 1000 mg/kg groups, and mature spermatid counts in the testis and sperm counts in the epididymis decreased in these groups. Among the marker enzymes of the testicular cells, LDH-X activity decreased, and β-glucuronidase activity, cytochrome P-450 content and cytochrome b5 content increased in the 1000 mg/kg group. Plasma testosterone concentration did not significantly alter in all the exposed groups. From these results, it was concluded that megadoses of pyridoxine affected the spermatogenesis and decreased reproductive organ weights in the rat.

Diffuse Pleural Rhabdomyosarcoma with Persistent Pleural Effusion

A unique case of embryonal rhabdomyosarcoma arising at the left pleura of a 7‐year‐old Japanese girl is reported. The present case was characterized by persistent pleural effusion, and the malignant cells incidentally found in it were the first diagnostic clue. The tumor showed a rare growth pattern involving diffuse thickening of the parietal pleura. Biopsy of the thickened parietal pleura upon thoracotomy revealed embryonal rhabdomyosarcoma largely composed of immature mesenchymal cells. Immunohistochemical demonstration of creatinine phos‐phokinase MM was most helpful among several types of immunostain for the histopathological diagnosis. Ultra‐structurally, thin filaments with primitive Z bands could be seen in some tumor cells. Intensive clinical examination revealed only diffuse thickening of the parietal pleura, which was reduced by chemotherapy. This is the first documented case of rhabdomyosarcoma arising at the pleura. Previous reports of rhabdomyosarcoma arising at unusual sites are reviewed and the histogenesis of this tumor is briefly discussed. Acta Pathol Jpn 39: 803 809, 1989.

Testicular damage by high doses of vitamin B6 (pyridoxine) in rats: A light and electron microscopical study

Male Wistar rats were administered daily intraperitoneal injections of 125, 250, 500, and 1000 mg/kg/day of vitamin B6 for 2 and 6 weeks and the histogenesis of the testicular damage was investigated. A reduction of germ cells was not prominent in the 2-week groups, whereas a delay in spermiation, degeneration of elongated spermatids, and Sertoli cell alterations were observed in the 500- and 1000-mg groups, although generally, these were relatively mild. Ectoplasmic specializations (ES), tubulobulbar complexes, and endoplasmic reticulum (ER) in the apical processes of Sertoli cells were irregularly arranged and their disappearance was also retarded. The Sertoli cell cytoplasm was often retracted and condensed. In the 6-week groups, no histological change in the testis was noted with the 125-mg dose. The retardation in spermiation and Sertoli cell alterations similar to those in the 500-mg dose 2-week group were observed in the 250-mg group. In the 500- and 1000-mg groups, germ cells were generally degenerated and markedly reduced in number. Multinucleate germ cells were mingled with anisocytotic germ cells, and openings of intercellular bridges were occasionally found. Sertoli cells also showed more severe alterations, such as focal disappearance of ES in earlier than ordinary stages, marked dilation of the ER, and markedly condensed or electron-lucent cytoplasm. These results suggest that the Sertoli cell damage may induce diverse germ cell degeneration in which retardation of spermiation occurs first.

Testicular Damage Caused by Inhalation of Ethylene Oxide in Rats: Light and Electron Microscopic Studies

Although testicular damage caused by ethylene oxide vapor (EtO) has been previously reported, the morphological changes occurring in seminiferous tubules remain unclear. We examined the time course of the testicular lesion induced by EtO in order to clarify its morphogenesis. Wistar rats were exposed to 500 ppm EtO for 6 hr per day, 3 times per week for 2, 4, 6, or 13 weeks through inhalation. In the 2-week exposure group, Sertoli cells often showed condensation and retraction of the cytoplasm, and dilatation of the endoplasmic reticulum (ER). In apical Sertoli cells, processes which encapsulated the heads of elongate spermatids, ectoplasmic specializations, and tubulobulbar complexes were often deformed and many elongate spermatids were degenerated. In the 4- and 6-week exposure groups, many degenerated Sertoli cells were present, and deformed germ cells, sometimes with multinucleation, appeared to make direct contact with each other without interlocation of Sertoli cell lateral processes. A few scattered immature Sertoli cells were evident in the 6-week exposure group. In the 13-week exposure group, seminiferous tubules containing almost all types of germ cells reappeared, mixed with atrophic tubules containing Sertoli cells only. In the former tubules, Sertoli cells often possessed regularly regenerated lateral processes, which were interposed between germ cells. These results indicate that the germ cell damage may be associated with damage to Sertoli cells. In spite of the intermittent exposure, focal regeneration of Sertoli cells appeared after 6 weeks of exposure to EtO and preceded patchy recovery of germ cells. Therefore, the data suggest that Sertoli cell regeneration may permit regeneration of germ cells.

Intranuclear membranous profiles in germinoma cells--a variant of nuclear pockets and intranuclear annulate lamellae.

When ultrastructurally examining 24 germinomas comprising 12 seminomas, 4 dysgerminomas, 1 mediastinal germinoma, and 7 intracranial germinomas, intranuclear membranous profiles were noticed in 17 germinomas, ranging from 20‐100 nm in width and 3^m in length. With occasional connections to the nuclear envelope through a small hole, intranuclear membranous profiles in germinoma cells were considered as clefts of the nuclear envelope. While most frequently situated under the inner nuclear membrane, they varied in configuration as well as distribution. As sequestered round mass of nuclear material, they were a variant of nuclear pockets containing nucleoplasm. Intranuclear annulate lamellae were occasionally present apart from the nuclear envelope and connected with nuclear clefts. Eleven of the twelve seminomas and 6 of the twelve non‐seminomatous germinomas showed intranuclear membranous profiles, and the incidence of such profiles was much higher in seminomas than in non‐seminomatous germinomas. Intranuclear membranous profiles facing the inner nuclear membrane were also noted in spermatogonia in adolescents and adults. It was suggested that intranuclear membranous profiles in germinoma cells could be structures following ones occasionally seen in spermatogonia. ACTA PATHOL. JPN. 35: 605–619, 1985.