Several hundred thousand primordial follicles are present in the mammalian ovary, however, only a limited number develop to the pre-ovulatory stage, and then finally ovulate. The others, more than 99%, will be eliminated through a degenerative process called 'atresia'. The endocrinological regulatory mechanisms involved in follicular development and atresia have been characterized to a large extent, but the precise temporal and molecular mechanisms involved in the regulation of these events have remained unknown. From many recent studies, it is suggested that the apoptosis in ovarian granulosa cells plays a crucial role in follicular atresia. Notably, death ligand-receptor interaction and subsequent intracellular signalling have been demonstrated to be the key mechanisms regulating granulosa cell apoptosis. In this review, we provide an overview of granulosa cell apoptosis regulated by death ligand-receptor signalling. The roles of death ligands and receptors [Fas ligand (FasL)-Fas, tumour necrosis factor (TNF)alpha-TNF receptor (TNFR), and TNFalpha-related apoptosis-inducing ligand (TRAIL)-TRAIL receptor (TRAILR)] and intracellular death-signal mediators [Fas-associated death domain protein (FADD), TNF receptor 1-associated death domain protein (TRADD), caspases, apoptotic protease-activating factor 1 (Apaf1), TNFR-associated factor 2 (TRAF2), and cellular FLICE-like inhibitory protein (cFLIP), etc.] in granulosa cells will be discussed.

Abstract. More than 99% of follicles undergo "atresia" during follicular development and growth. Follicular atresia is predominantly regulated by granulosa cell apoptosis. However, the intracellular signaling pathway of apoptosis in granulosa cells has not been revealed. In the present study, we examined changes in the expression of BH3-interacting domain death agonist (Bid) and Bcl-2-associated X protein (Bax), which are considered to promote the cell death ligand/ receptor-mediated process in mitochondrion-dependent type II apoptosis, in porcine granulosa cells during atresia. Levels of mRNA and protein of Bid and Bax were determined by the reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting techniques, respectively. Levels of Bid and Bax mRNA and protein were markedly increased in granulosa cells of early atretic follicles compared with those of healthy follicles. In situ hybridization and immunohistochemical staining revealed that mRNA and protein of Bid and Bax were present in the granulosa cells, though only traces were found in healthy follicles; however, strong staining was noted in atretic follicles. These results indicate that Bid and Bax appear to be signal transduction factors in granulosa cells during follicular atresia and appear to play proapoptotic roles and confirm that the porcine granulosa cell is a mitochondrion-dependent type II apoptotic cell. Key words: Bcl-2-associated X protein (Bax), BH3-interacting domain death agonist (Bid), Follicular atresia, Mitochondrion-dependent type II apoptotic cell, Pig ovary (J. Reprod. Dev. 57: [421][422][423][424][425][426][427] 2011) n mammalian ovaries, more than 99% of follicles degenerate at various stages of follicular growth and development [1]. The degeneration is explained, at least in part, by the apoptosis of granulosa cells [2][3][4][5][6]. In the early stages of follicular atresia in pig ovaries, biochemical and morphological characteristics typical of apoptosis, namely nuclear fragmentation, chromatin condensation and cell shrinkage, are observed in scattered granulosa cells located on the inner surface of the follicular wall, but not in cumulus cells, oocytes or the cells of internal or external thecal layers [7,8]. However, the intracellular signal transduction pathway of apoptosis in granulosa cells of pig ovaries is not well understood.Selective apoptotic cell death is induced by cell death ligand/ receptor systems, including Fas ligand (FasL; also called Apo-1 ligand or CD95 ligand) and Fas (also called Apo-1 or CD95), tumor necrosis factor (TNF)-α and TNF receptors (TNFRs) and TNFrelated apoptosis-inducing ligand (TRAIL) and TRAIL receptors (DR4 and 5) [9][10][11]. The cell death ligand/receptor-mediated apoptotic signaling pathway is suggested to be as follows [12][13][14][15][16][17][18]: When trimerized cell death ligands bind with trimerized death receptors located on the cell membrane, the receptors are activated. An adaptor protein (Fas-associated death domain protein: FADD) binds with an activated rece...

The objectives of this study were to determine the individual and herd-level prevalence and genotype of Cryptosporidium and to identify putative risk factors associated with Cryptosporidium spp. infections in water buffaloes in northeast Thailand. Fecal samples from 600 water buffaloes of 287 farms in six provinces were collected and tested using DMSO-modified acid-fast staining and polymerase chain reaction. The overall prevalence of Cryptosporidium infections in buffaloes was 5.7 and 8.7% among individual animals and herds, respectively. The provinces with highest infected Cryptosporidium were located in the Sakon Nakhon Basin in the northern part of the region. In addition, higher herd prevalence was observed among farms with more than five buffaloes (30%) than those with five or less animals (16.2%). Thirty (88.2%) of the 34 Cryptosporidium-positive samples were Cryptosporidium parvum and four (11.8%) were Cryptosporidium ryanae.

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