Scanning electron microscopic and cytochemical analyses of alveolar and peritoneal macrophages of mice, dogs and cats.

Alveolar and peritoneal macrophages (MPs) of mouse, dog and cat were compared in relation to their scanning electron microscopic features and the lysosomal activities of nonspecific esterase, acid phosphatase, and beta-glucuronidase. The long spindle shape of peritoneal MPs differed from the spherical form of alveolar MPs in all species. There was no difference in the morphological findings among the three animals. Murine alveolar and peritoneal MPs were strongly positive for all three enzymes. Canine and feline alveolar and peritoneal MPs were strongly positive for acid phosphatase and beta-glucuronidase, but weakly positive for nonspecific esterase. These results strongly suggest that acid phosphatase and beta-glucuronidase can be used as markers of the MPs in healthy dogs and cats.

[Study on the organization of chromatin and chromosome in mouse spermatogenic cells by scanning electron microscopy].

It remains unclear about the intermediate construction of chromosome due to its highly compact nature and the limitation in methods. The present study was designed to investigate the construction of chromatin and mitotic chromosome in situ with scanning electron microscopy. Mouse testes were selected as the material, because of in which the spermatogenic cells divide actively and successively to form the sperm. Such a feature would be able to study the structure of mammalian chromatin and chromosomes along with the change of nuclear cycle. The animal were perfused with 200 ml of 0.075 mol/L KCl hypotonic solution to remove blood and placed for 15-20 min on ice followed by 0.5% glutaraldehyde and 0.5% formaldehyde for fixing. Through treated by the routine process of fractured and freeze dried with t-butyl alcohol, the specimens were then coated with a 3 nm thick platinum and observed with Hitachi S-430 scanning electron microscopy. It was found that the hypotonic treatment with 0.075 mol/L KCl solution was suit for demonstrating the nuclear structure, when the organelles were well preserved. The chromatin fibers of 10-30 nm and 80-125 nm in diameter could be recognized in the interphase nuclei, which were arranged losely at the region of euchromatin, and folded with each other into chromatin masses at the region of heterochromatin, while the chromatin fibers with the diameter of 80-125 nm often could be viewed on the mitotic chromosomes. Since its presence in interphase nuclei and mitotic chromosomes, it was considered that the chromatin fibers with 80-125 nm in diameter might play a role in the condensation of chromosome, serve as a type of the intermediate structure.

Scanning and transmission electron-microscopic study of the development of the podocyte in the human fetus.

The metanephric kidneys of seven human fetuses at 11-17 weeks' gestation were examined by scanning and transmission electron microscopy in order to evaluate differentiation of glomerular podocytes. When glomeruli were in the stage of S-shaped bodies, the surface of the visceral epithelium of renal corpuscles was smooth, with indistinct cell borders. As the glomeruli developed, visceral epithelial cells of renal corpuscles became spherical and resembled clusters of grapes in dense aggregation. In this stage, processes and foot processes were simultaneously formed at the base of epithelial cells. As glomeruli further differentiated, visceral epithelial cells of renal corpuscles began to separate from one another and became flat with the development of vascular loops. Processes and foot processes were exposed for the first time in Bowman's space. In this stage, the degree of differentiation of epithelial cells varied widely among various sites of the glomerulus. As glomeruli developed further, projections became more complex and epithelial cells began to show structures similar to those of adult epithelial cells. The adjacent foot processes arose from different cells throughout the period of morphological differentiation.