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PubMed1976

[Electron-microscopic study of the nuclear membrane of the PKEV cells during mitosis. 1. The breakdown of the nuclear membrane (prophase, prometaphase, metaphase)].

An ultrastructural study on dividing PKEV cells provided a possibility to distinguish between certain stages of their desintegration. The changes preceding fragmentation of the nuclear envelope commence with desorganization of its structural components: vanishing of granular peripherial chromatin layer; appearance of the pores without central granules; formation of deep invaginations of the nuclear membranes. The desintegration of the nuclear envelope starts from the disapearance of many pores and the appearance of perforations almost of the same size. Simultaneously, the number of polysomes is reduced on the outer membrane of the nuclear envelope and in the cytoplasm. Specific features of the nuclear envelope being lost it becomes undistinguishable from the reticulum elements. On serial sections, no contacts were observed between chromosomes and membranous elements.

Animals↗
PubMed1975

Germ cell development and the meiotic prophase in the fetal horse ovary.

A histological study of the developing germinal epithelium in the fetal horse ovary shows an enormous wastage of oocytes during the meiotic phase, between Days 73 and 150 of pregnancy. The first groups of oocytes to enter this phage undergo mass degeneration and eventually disappear; few, if any, oocytes develop to primordial follicles. Peripheral oogonia, dividing by mitosis, give rise to more oocytes which pass through the same changes and are also reduced by degeneration, but by Day 150 primordial follicles are fairly common.

Animals↗
PubMed2000

[Studies on the distribution of actin during meiotic prophase I of Nicotiana rustica L].

The Pollen Mother Cells of Nicotiana Rustica L. were studied using the techniques of immunofluorescence microscopy and protein A-colloidal gold IEM. Immunofluorescence microscopy indicates the presence of actin in both nuclei and cytoplasm. IEM observation shows that gold particles are present in cytoplasm, chromatin and cytomictic channels. These results indicate that actin has some relation with chromatin condensing at synizesis. Moreover, actin may also play an important role in cytomixis.

Actins↗
PubMed1989

[Effect of heterozygosity for insertions of homogeneously stained regions in chromosome 1 of the house mouse on synapsis in meiotic prophase].

Electron microscope analysis of surface-spread synaptonemal complexes (SC) in oocytes and spermatocytes from double cis heterozygotes for Is(HSR; 1C5)1Icg and Is(HSR; 1E3)2Icg was carried out. Aberrant chromosomes were isolated from the feral population of Mus musculus musculus of Novosibirsk. They contain homogeneously stained regions of total length of about 30% of Chr 1 mitotic metaphase. Heteromorphic bivalents of Chr1 with different lengths of the lateral elements of SC and the loop in the intermedial position were revealed in 4.4% spermatocytes and 20% oocytes of heterozygous animals. The loop size depends on the stage of meiosis: it is maximal at late zygotene and decreases up to disappearance during pachytene.

Animals↗
PubMedDate not supplied

Meiotic prophase in the left embryonic testis of the Japanese quail (Coturnix coturnix japonica L.).

Spontaneous, transitory feminization of the left embryonic testis occurs in the majority of male Japanese quails from day 11 of incubation until the 2nd day after hatching. The feminized gonad is composed of a testicular part and of an ovarian-like cortical region, which develops outside the tunica albuginea. The cortical region contains numerous germ cells some of which enter meiosis on day 11 (i.e. at the time characteristic of female germ cells) and reach pachytene on day 14. Cortical regions are best developed on day 16 (day of hatching), but regression, accompanied by degeneration of many germ cells, begins shortly afterwards. The mechanism of feminization of the left embryonic testis is discussed.

Animals↗