ovarian-tissue-culture-to-visualize-phenomena-in-mouse-ovary

Ovarian Tissue Culture to Visualize Phenomena in Mouse Ovary

Mammalian females periodically ovulate an almost constant number of oocytes during each estrus cycle. To sustain such regularity and periodicity, ...

Aichi Medical University

Follicle growth in the mammalian ovary is coordinately controlled by multiple factors to sustain periodic ovulation. In this study, we investigated the role of progesterone on follicle growth in the mouse ovary. As the concentration of progesterone changes during the estrus cycle, we cultured the sliced mouse ovary in a medium containing 10 ng/ml, 100 ng/ml, and 1 μg/ml progesterone. Progesterone promoted the growth of primordial to primary follicles at 100 ng/ml, while it suppressed the growth of secondary follicles at 1 μg/ml. Follicles at other developmental stages in the cultured ovary were unaffected with different concentrations of progesterone. The number of ovulated oocytes increased in the medium containing 100 ng/ml progesterone but decreased in the presence of 1 μg/ml progesterone. Follicles expressed two types of progesterone receptors, progesterone receptor (PGR) and PGR membrane component 1 (PGRMC1). While PGR shows transient expression on granulosa cells of Graafian follicles, PGRMC1 expresses in granulosa cells of developing follicles. These results suggest that progesterone controls the growth of developing follicles through PGRMC1. Our study shows that the effect of progesterone on ovulation and follicle growth in mouse ovary is dependent on the concentration of progesterone and the follicle stage.

The concentration-dependent effect of progesterone on follicle growth in the mouse ovary.

To visualize and analyze follicle development in ovarian tissue culture using physiological concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in order to establish an ovarian tissue culture system that enables efficient in vitro growth of follicles.

Follicle dynamics: visualization and analysis of follicle growth and maturation using murine ovarian tissue culture.

The number of ovulated oocytes is different among mammals but does not vary much within the same species. In order to sustain periodic ovulation, follicular development must be coordinated at the tissue level. Elucidating the regulatory mechanisms of follicular development is difficult because the ovary has a complicated structure and it takes a long time for primordial follicles to develop into Graafian follicles. Therefore, it is not possible to observe follicular development by conventional experiments. The authors previously developed a new ovarian tissue culture method that enabled the observation of follicular development from the early follicle stage. These findings indicated that follicular interactions are important in regulating follicular development and ovulation. This review describes the current methods of observing follicular development in the ovary and the regulatory mechanisms of follicular development.

Observation of the dynamics of follicular development in the ovary.

Proper development and maturation of oocytes requires interaction with granulosa cells. Previous reports have indicated that mammalian oocytes connect with cumulus cells through gap junctions at the tip of transzonal projections that extend from the cells. Although the gap junctions between oocytes and transzonal projections provide a pathway through which small molecules (< 1 kDa) can travel, it is unclear how molecules > 1 kDa are transported between the oocytes and cumulus cells. In this study, we presented new connections between oocytes and granulosa cells. The green fluorescein protein AcGFP1 localizing in oocyte cell membrane, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate and dextran conjugates (10,000 MW) injected into the oocytes, which were unable to pass through gap junctions, were diffused from the oocytes into the surrounding granulosa cells through these connections. These connects an oocyte to the surrounding cumulus and granulosa cells by fusing with the cell membranes and forming a large complex during follicle development. Furthermore, we show two characteristics of these connections during follicle development-the localization of growth and differentiation factor-9 within the connections and the dynamics of the connections at ovulation. This article presents for the first time that mammalian oocytes directly connect to granulosa cells by fusing with the cell membrane, similar to that in Drosophila.

Article	Year
The concentration-dependent effect of progesterone on follicle growth in the mouse ovary. The Journal of reproduction and development\| PubMed ID: 28321005	2017
Follicle dynamics: visualization and analysis of follicle growth and maturation using murine ovarian tissue culture. Journal of assisted reproduction and genetics\| PubMed ID: 29080194	2018
Observation of the dynamics of follicular development in the ovary. Reproductive medicine and biology\| PubMed ID: 29259446	2017
Mouse oocytes connect with granulosa cells by fusing with cell membranes and form a large complex during follicle development. Biology of reproduction\| PubMed ID: 29590310	2018

Kouji Komatsu

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