Gamma-glutamyl transpeptidase (GGT) has been one of useful marker enzymes in experimental hepatocarcinogenesis in rodents, with an implication of its onco-fetal property. Human and experimental neoplasms of various organs have been investigated for their GGT activities from the same standpoint in experimental hepatocarcinogenesis. We have recently demonstrated the induction of GGT activity in the early lesions of experimental thyroid carcinogenesis in rats. In the present study, the distribution of rather strong GGT activity was confirmed in microscopic putative precancerous lesions to thyroid carcinomas induced by diisopropanolnitrosamine (DIPN), an established thyroid carcinogen. In contrast to no GGT activity in adult rat thyroid follicles, a significant reaction for GGT was revealed in fetal rat thyroid tissues in this investigation. From these facts, it is concluded that GGT is a potent histochemical marker during experimental thyroid carcinogenesis in rats, proposing an onco-fetal property of GGT also in the thyroid.
The ultrastructural localization of serotonin (5-HT)-like immunoreactivity was investigated in human gut endocrine cells by the block-staining method using horseradish peroxidase (HRP)-labeled anti-5-HT rabbit (Fab')2. The reactive products against 5-HT were satisfactorily demonstrated on the membrane-bound and/or non-membrane-bound ribosomal granules as well as on the basally accumulated biconcave granules as seen in typical enterochromaffin (EC) cells. The cross-reactivity of the anti-5-HT antisera to various tryptophan related compounds and the other monoamines was examined by the 125I labeled protein A (IPA) assay system. The anti-5-HT antisera were completely neutralized by serotonin-bovine serum albumin (BSA) and N-acetylserotonin-BSA conjugates and incompletely by free serotonin creatininesulfate. No inhibition of the antibody binding activity was observed when the antisera were preincubated with tryptophan and its related compounds or other monoamines. In conclusion, our results confirmed the ultrastructural localization of 5-HT-like immunoreactivity in EC cells and the availability of the blockstaining method using HRP-labeled anti-5-HT (Fab')2 for ultrastructural immunohistochemistry.
An immunohisto-cytochemical localization of glutathione-peroxidase (GSH-PO) in rat testicular interstitial macrophages was studied on 1) normal untreated rats 2) 2 weeks after hypophysectomy 3) and with gonadotropin administration for 1 week after hypophysectomy, in order to clarify the role of GSH-PO. In group 1, an immunohisto-cytochemical localization of GSH-PO was observed in cytosol as a characteristic lysosome-like structure. In group 2, immunohistochemically, the number of GSH-PO positive macrophages decreased as compared with that of the group 1. However, in group 3, immunohistochemically, the number of GSH-PO positive macrophages increased as compared with that of group 2. An intracellular lysosome-like GSH-PO also increased as compared with that of the other groups. These findings suggest that a very close relationship lies between immunocytochemical localization of GSH-PO in the testicular interstitial macrophages and testosterone production in the testicular Leydig cells. The possible role of GSH-PO in the testicular interstitial macrophage is discussed.
The transport of calcium ions in correlation with the molting cycle was studied in the columnar epithelium of the crayfish gastrolith disc tissue by three cytochemical methods. In material fixed by freeze-substitution or potassium oxalate-glutaraldehyde, electron-dense deposits were found only in the hypertrophied mitochondria of the epithelium. In material fixed with potassium antimonate-OsO4, however, a number of fine deposits were observed throughout all membraneous structures. The emission of calcium K line was demonstrated only in the deposits on the mitochondria in electron probe X-ray microanalysis with the material fixed with acrolein gas, oxalate-glutaraldehyde, and antimonate-OsO4. These results may contribute to understanding the role of mitochondria in calcium transport when a large amount of calcium ions is moved from gastrolith epithelium to the outer molting epithelium or vice versa.