1,721,253 research outputs found
Fine structural markers of human oocyte quality in assisted reproduction.
No full textAfter completing its maturation, the human oocyte acquires very peculiar fine structural features. In this review we describe by LM, TEM and SEM the nuclear and cytoplasmic changes, as well as the changes in the texture of the ZP, occurring in the human oocyte during the final stages of maturation. Oocytes were obtained during ART cycles and destined to morphological evaluation after the informed consent of the patients. The critical analysis of the data reviewed leads us to emphasize that: 1. both the completion of the maturative changes in the preovulatory period and the absence of degenerative alterations in the cytoplasmic microdomains of the human mature oocyte ultimately render the female gamete competent for fertilization; 2. several minute cellular aberrations, detectable only by electron microscopy analysis, may occur in the human oocyte as the consequence of the application of ART protocols (IVM and cryopreservation, in particular) and could be responsible for ART failures, even affecting early embryo development
ULTRASTRUCTURAL IMAGING OF MOUSE THECA INTERNA CELLS IN DEVELOPING AND ATRETIC OVARIAN FOLLICLES
No full textItalian Journal of Anatomy and Embryolog
Focal cell contacts detected by ruthenium red, triton X100 and saponin in the granulosa cells of mouse ovary
No full textAbstract
Granulosa cells in growing follicles of mouse ovary, observed after treatment with ruthenium red (RR) as described by Luft (1971a, b), appeared to be covered by a continuous well-defined layer. On the contrary, treating granulosa cells with 1% Triton X100 (Vaccaro and Brody, 1981), followed by RR staining, resulted in the complete extraction of the plasma membrane coat (Triton does not affect the basement membrane and extracellular matrix proteoglycans). The use of 0.02% saponin together, with the RR stain, or 0.1% Triton X100 followed by RR staining, allows good visualization of follicular basement membrane and extracellular matrix proteoglycans without destroying cell morphology. Using this technique, we observed the extraction of the plasma membrane coat, but focal RR-stained condensations that were unaffected by saponin or 0.1% Triton X100 treatment were observed between plasma membranes of granulosa cells located around the periphery of large Graafian follicles. In some cases, RR condensations were located at the apex of plasmalemmal evaginations, in proximity to adjacent granulosa cells. Focal condensations of RR stain were never observed in secondary follicles. Present evidence suggests that focal cell contacts are mediated by transmembrane intercalated glycoproteins or proteoglycans and consequently play a role in cell adhesion. Their presence among granulosa cells of only very large Graafian follicles may be related to the maturation process of granulosa cells
Morphological studies of polycystic mouse ovaries induced by dehydroepiandrosterone.
No full textorphological alterations induced by dehydroepiandrosterone (DHA) were studied in polycystic mouse ovaries (PCO). Treated mice showed ovulatory failure and cystic changes; cysts and follicles in various stages of growth and atresia were present although corpora lutea were absent. The levels of testosterone, dihydrotestosterone, 3 alpha- and 3 beta-androstanediol, estrone and androstenedione increased, whereas estradiol was not detectable. The ultrastructure of granulosa cells in healthy and atretic follicles was similar to that of control animals, although the membrana granulosa in cysts was reduced to a monolayer of flattened cells. The theca interna of healthy and atretic follicles and ovarian cysts showed ultrastructural signs of abnormal steroidogenic stimulation. No significant differences (0.7 less than P less than 0.8) were found between the extensive surface area of gap junctions of healthy follicles of control and DHA-treated animals. On the P-face of granulosa cells of large healthy follicles, meandering strands of tight junctional particles were observed; their average length was significantly longer than those in healthy follicles of control animals (P less than 0.001). This increase was probably related to the large amounts of androgens present in the treated animals. Theca interna cells possessed small gap junctions; no significant differences (P greater than 0.9) in gap-junction surface area were observed between DHA-treated and control animals. These results suggest that the size of gap junctions is probably unrelated to the steroidogenic activities of theca cells
Topographical structural variations of the human long saphenous vein and its age related remodelling as revealed by correlated light and scanning electron microscopy.
No full textRecent insights in the ultrastructure of human oocyte
No full textThe positive outcome of assisted reproductive technologies (ART) depends on the oocyte quality, in terms of maintenance of full morphofunctional integrity during its complex and long maturation. In fact, the completion of maturation, in the preovulatory period, both in vivo and in vitro, as well as the preservation of cytoplasm, permit the oocyte to become competent for fertilization. The oocyte ultrastructure reflects the developmental competence of this cell that, therefore, has been object of several studies, especially after ART. Since, after completion of its maturation, the human oocyte acquires very peculiar fine structural features, likely influenced by the application of ART, we studied the above changes in human oocytes, from young and aged women, after informed consent, subjected to the most recent ART protocols including, in vitro maturation and or cryopreservation. In this paper, we reviewed by electron microscopy and correlated techniques, the changes of the nucleus, cytoplasm and zona pellucida, occurring in the human oocyte during the final stages of maturation, after ART. We could observe that the human oocyte undergoes a reorganization of its genome, ooplasm and extracellular matrix characterized by neogenesis, modification and redistribution of organelles, membranes and glycoproteins of the ZP. Our analysis showed that the completion of the maturation in the preovulatory period and the absence of cytoplasmic degenerative alterations, make the female gamete competent for fertilization. However, several subcellular aberrations, detectable only by electron microscopy analysis, occur in the oocyte as the consequence of the application of ART protocols (IVM and cryopreservation, especially) and could be responsible for ART failures, or even affecting early embryo development. Electron microscopy observations, associated with other morphological studies, and analyzed together with clinical, epidemiological, biological, molecular/ biochemical data, are useful in the assessment of the cell structural integrity, in order to define the proper “oocyte health” state
- …
