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  • Title: [Ultrastructural observation of the ovulatory changes in the capillary of the human follicular apex (author's transl)].
    Author: Okamura H, Okuda Y, Kanzaki H, Takenaka A, Morimoto K, Nishimura T.
    Journal: Acta Obstet Gynaecol Jpn; 1981 Feb; 33(2):215-21. PubMed ID: 7234334.
    Abstract:
    To clarify its possible participation and mode of action in follicle rupture at human ovulation, the capillary in the apex of the ovarian follicle was investigated electronmicroscopically with 16 human ovaries. In the follicle at the mid-proliferative phase with 6 mm diameter, capillary lumen was narrow and empty. Capillary vessels observed in the theca interna of the preovulatory follicle were dilated and filled with blood cells. Their endothelial cells had indented nuclei and elongated thin cytoplasm with unusually irregular membranous protrusions. In cytoplasm there were numerous vesicles, some of which had fine granule-like contents of low electron density to be released into extracapillary space. These results indicate increased capillary permeability due to active transport around the time of ovulation. Polymorphonuclear leucocytes, rich in specific granules containing collagenase activity, were often observed in the capillary lumen as well as extracapillary space only close to the time of ovulation. This observation implies possible roles of leucocytes in collagen degradation. The present ultrastructural results suggest that the vast capillary network in the follicle wall plays an important role in the mechanism of follicle rupture through its increased permeability and collagenolytic activities of leucocytes.
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