Ultrastructural study of the coiled body and a new inclusion, the “mykaryon”, in the nucleus of the adult rat sertoli cell

Abstract

Random and serial thin sections of the nucleus in adult rat Sertoli cells were examined by electron microscopy. Besides the previously reported nucleoli and heterochromatin masses, the nuclei contain a coiled body and a new structure, the "mykaryon." The coiled body is 835 nm in maximum diameter. It is composed of distinct elements referred to as "coils." They are 32 nm wide on average and resemble the nucleolar pars fibrosa in their intense staining with heavy metal salts and their composition of narrow filaments. The coiled body is often close to a nucleolus, though no direct contact is established, and it sometimes exists at a distance from the nucleolus. The mykaryon is spherical, 460 nm in maximum diameter, and composed of a tridimensional network of 7-26 nm-wide electron-opaque "cords" separated by slightly thinner spaces. It has not been observed in the vicinity of a nucleolus. A literature survey showed no previous mention of a structure similar to the mykaryon. The coiled body and the mykaryon are interpreted as normal constituents of the Sertoli nucleus in the adult rat.

Studies on Thick Sections of the Nucleus of Mouse Sertoli Cells Using an Electron Microscope Operating at 300 kV

“…The present findings indicate that the Sertoli cell nuclei show a characteristic distribution of some dense bodies, which closely resemble the coiled body described by Schultz (1989), but they are occasionally attached to the nucleolus. However, the previous study demonstrated that the coiled body exists in situ without structural relationship to the nucleolus.…”

“…The formation of the perinucleolar bodies or heterochromatin is still unclear in the present study. Schultz (1989) reported a coiled body and mykaryon in the nucleus of the adult rat Sertoli cell using thin sections. He noted that the coiled body was composed of distinct elements referred to as "coils" and resembled the nucleolar pars fibrosa in their intense staining with heavy metal salts.…”

“…These examinations permitted an analysis of the nucleolar organization and indicated the existence of nucleoli, heterochromatin bodies, nuclear bodies , coiled bodies and mykaryon (Schulze , 1974;Krimer, 1977;Jean et al, 1983;Schultz , 1989). Thus, four principal components were recognized in the Sertoli cells of mice (Paniaqua et al ., 1986): 1) a spherical fibrillar center, 2) a compact granular portion , 3) a reticular portion with intermingled pars fibrosa and pars granulosa and 4) a nucleolar associated chromatin body surrounding the nucleolus .…”

“…Using this approach, the architecture of the Sertoli cell nucleus has also been described in mammalian species (Bustos-Obregon and Esponda, 1974; Krimer, 1977;Mine and Knibiehler 1982;Paniaqua et al, 1986). Therefore, morphological characteristics such as the nucleolus, perinucleolar body, round body, coiled body and mykaryon have been observed at the ultrastructural level (Jean et at., 1983;Schultz et al, 1984;Schultz, 1989). This evidence was mainly based on examination of thin sections that revealed only parts of the Sertoli cell nucleus.…”

Protein Kinase C Increases 11β‐Hydroxysteroid Dehydrogenase Oxidation and Inhibits Reduction in Rat Leydig Cells

“…The physiological significance of regulatory changes in 11␤HSD lies in the fact that Leydig cells contain glucocorticoid receptors and are the primary target of glucocorticoid action in the testis (Hales and Payne, 1989;Schultz, 1989;Stalker et al, 1989;Ge et al, 1997b). Because glucocorticoid-induced suppression of testosterone production is mediated by glucocorticoid receptors (Hales andPayne, 1989, Monder et al, 1994b), the intracellular concentration of glucocorticoid within the Leydig cell should determine the magnitude of its effect.…”