Electron-microscopic study of silver staining of nucleoli in growing oocytes of rat ovaries

Abstract

The nucleoli of dictyate-stage growing oocytes in rat ovaries were examined both with routine electron microscopy and electron microscopy after silver nitrate and ammoniacal silver nitrate (Ag-AS) staining. The nucleoli of the unilaminar follicular oocytes consist of twisted strands of dense fibrillar components, aggregates of granular components, and small fibrillar centers. After Ag-AS staining, silver grains are numerous on the dense fibrillar strands, fewer on the fibrillar centers, and very sporadic on the granular aggregates. The same stainability of three nucleolar components with the Ag-AS method was also confirmed in the nucleoli segregated by actinomycin D. During the transition of growing oocytes from bilaminar to plurilaminar follicle stage, the nucleolar dense fibrillar strands gradually conglomerate and are transformed into large and compact spherules. The stainability of dense fibrillar components with the Ag-AS method was lost along with this nucleolar transformation. These results may provide some new clues on the functional significance of Ag-AS-positive proteins in the nucleoli.

Hematoxylin Staining Reveals a Decrease in Nucleolar Diameter of Pig Oocytes Before Germinal Vesicle Breakdown

“…Electron microscopic observations have revealed that nucleoli of full-grown oocytes have a homogenous structure without well-defined compartments seen in somatic nucleoli [3, 4]. Such a change in nucleolar morphology during oocyte growth has been described in the pig [2], mouse [5], rat [6], cow [7] and human [8]. The relationship between the chromatin and nucleolus also changes during oocyte growth [2].…”

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

“…20) . Only a little ribosomal RNA synthesis has been considered to occur in full-grown mouse oocytes (10,14,19) . In the present study, however, the stainability of fibrillar centers and the adjoining zones of dense fibrillar components to GA-Bi staining did not appear to decrease during the transition from the bilaminar or plurilaminar follicle stage to the antral follicle stage.…”

Immunocytochemical localization of actin in the nucleolus of rat oocytes

“…In the dictyate nucleus of growing oocytes, diplotene chromosomes are noncondensed and the nucleolus has a reticulated structure consisting of dense fibrillar components, aggregates of granular components, and small fibrillar centers. During further oocyte growth, the nucleolus goes through sequential ultrastructural changes and becomes entirely composed of a homogeneous proteinic compact mass by the end of follicular growth [2,3,6,9,24,30]. In the majority of mammalian species, the highly compact nucleolus, after resumption of meiosis, is progressively reduced in size and disappears simultaneously with the development of the chromosomal pattern.…”