Electron microscopic study on the bismuth staining of nucleoli in growing mouse oocytes.

Abstract

The electron microscopic bismuth staining method of Locke and Huie (16) was applied to the nucleoli of dictyate-stage growing mouse oocytes. After bismuth staining following glutaraldehyde fixation (GA-Bi staining), bismuth was largely localized in the fibrillar centers and the adjoining zones of dense fibrillar components not only in the nucleoli of growing oocytes during the unilaminar, bilaminar and plurilaminar follicle stages, but also in the nucleoli of mature antral-follicular oocytes. These results suggest that the materials stained with the GA-Bi method in the nucleoli of mouse oocytes may have no direct correlation with the transcriptional activity of ribosomal DNA.In the nucleoli of antral follicular oocytes, the large spherical bodies, consisting of condensed fibrillar components, were unstained with GA-Bi staining but densely stained with bismuth following formaldehyde fixation (FA-Bi staining). This fact suggested the presence of nuclear basic proteins such as histones and protamines in these nucleolar bodies.