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Mammalian Ovaries (mammalian + ovary)
Selected AbstractsPre-ovulatory temperature gradients within mammalian ovaries: a reviewJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 7-8 2005R. H. F. Hunter Summary The existence of a temperature gradient between the testis and deep body temperature has been accepted for many years. It is based on two simultaneous principles: cooling of the testis through the scrotal wall and transfer of heat between the testicular blood vessels. The ovary is positioned in the abdomen; a temperature difference parallel to the male system therefore seems less likely. However, the temperature of large follicles has been found to be 0.5 to 1.5 °C cooler than the ovarian stroma in rabbits, pigs and, probably, women. The temperature difference seems to be based on a heat-consuming process in the expanding follicullar fluid, and a local transfer of heat between intra-ovarian blood vessels. The reason for the temperature gradient is not yet known; one may speculate of a common reason for the cooling of the gamete in male and female. [source] Changes in expression of anti-apoptotic protein, cflip, in granulosa cells during follicular atresia in porcine ovariesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2005Fuko Matsuda-Minehata Follicular selection is performed in mammalian ovaries, as most follicles undergo atresia during follicular development and growth. Follicular regression is indicated to begin with granulosa cell apoptosis. To reveal the molecular mechanisms of the selection, we examined the changes in the levels of cellular-Flice like inhibitory protein (cFLIP) expression in porcine granulosa cells. cFLIP is the homologue of intracellular apoptosis inducer (procaspase-8/Flice), and has two alternative splicing isoforms: cFLIP short form (cFLIPS) and long form (cFLIPL). By competing with caspase-8, cFLIP inhibits apoptosis initiated by death receptors. The changes in the levels of cFLIPS and cFLIPL mRNA and protein expression in granulosa cells were determined by RT-PCR and Western blotting, respectively. cFLIPL mRNA and protein were highly expressed in granulosa cells of healthy follicles and decreased during atresia. cFLIPS mRNA levels in granulosa cells were low and showed no change among the stages of follicular development, and its protein level was extremely low. We examined the changes in the localization of cFLIP mRNAs in pig ovaries by in situ hybridization and found that cFLIPL is abundant in granulosa cells of healthy follicles in comparison with those of atretic follicles. Immunohistochemical analyses demonstrated that the cFLIP protein is highly expressed in the granulosa cell of healthy follicles but weakly expressed in that of atretic follicles. We presumed that cFLIP, especially cFLIPL, plays an anti-apoptotic role in the granulosa cells of healthy follicles of pig ovaries, and that cFLIP could be a major survival factor that determines whether growth or atresia occurs in porcine follicles. © 2005 Wiley-Liss, Inc. [source] Renewed debate over postnatal oogenesis in the mammalian ovaryBIOESSAYS, Issue 8 2004Chuck Greenfeld The central dogma of female reproductive biology has long held that oogenesis ceases prior to birth in mammals. During the first half of the last century, there was much debate about whether this was the case or whether oogenesis continued in the postnatal ovary. A report in 1951 effectively put an end to this debate and laid the foundation for the dogma. A new paper by Johnson et al. (2004)1 resurrects the debate over whether postnatal oogenesis occurs in the mammalian ovary. If confirmed, this would have tremendous impact on issues related to female fertility and reproductive longevity. BioEssays 26:829,832, 2004. © 2004 Wiley Periodicals, Inc. [source] | ||||||||||