Colleoni S, Luciano A M, Gandolfi F
Laboratorio di Tecnologie della Riproduzione, CIZ, Istituto Sperimentale Italiano Lazzaro Spallanzani, Cremona, Italy.
Reprod Domest Anim. 2004 Apr;39(2):70-5. doi: 10.1046/j.1439-0531.2003.00479.x.
Horse is a seasonal breeder and information on oocyte quality outside the breeding season is very limited. Ovaries obtained at the slaughterhouse are a convenient but often limited source of oocytes in this species. As the low quantity of ovaries leads to an intensive use of all available material, it would be useful to know whether ovaries collected during the non-breeding season are suitable for in vitro maturation (IVM). In an attempt to characterize the effect of season on oocyte quality, we investigated the permeability of the gap junctions (GJ) present between cumulus cells and oocytes because of their important role in oocyte growth and maturation. We also compared the effect of supplementing the maturation medium with bovine serum albumin (BSA) or oestrus mare serum (EMS). A total of 645 oocytes isolated from 158 and 154 ovaries collected during the breeding and the non-breeding season, respectively, were used in this study. Oocytes were matured for 30 h in TCM 199 supplemented either with 10% EMS or with 4 mg/ml BSA. The presence of permeable GJs between cumulus cells and oocytes was investigated with the injection of a 3% solution of the fluorescent dye Lucifer yellow into the ooplasm. No differences in efficiency of oocyte retrieval or oocyte meiotic competence were detected between oocytes collected during the breeding and non-breeding season. The vast majority (90%) of the oocytes collected during the breeding season had fully functional communications with their surrounding cumulus cells but such communications were completely interrupted in 55.3% of the oocytes collected during the non-breeding season. During the non-breeding season, the proportion of oocytes whose communications with cumulus cells were classified as closed or intermediate at the end of maturation was lower in the group matured with BSA than with EMS (71.4 vs 97.7, p < 0.05). The same trend, although not statistically significant, was observed during the breeding season also. The presence of BSA caused an incomplete cumulus expansion during both seasons. Our data indicate that oocytes collected during the non-breeding season do not show any meiotic deficiency but lack active communication with the surrounding cumulus cells at the time of their isolation from the ovary. No data are available at present for determining the consequences on the developmental competence even if data from other species suggest that this is likely.
马是季节性繁殖动物，关于繁殖季节以外的卵母细胞质量的信息非常有限。在屠宰场获取的卵巢是该物种卵母细胞的一个便利来源，但通常数量有限。由于卵巢数量少导致对所有可用材料的大量使用，了解在非繁殖季节收集的卵巢是否适合体外成熟（IVM）将很有帮助。为了试图描述季节对卵母细胞质量的影响，我们研究了卵丘细胞和卵母细胞之间存在的缝隙连接（GJ）的通透性，因为它们在卵母细胞生长和成熟中起重要作用。我们还比较了在成熟培养基中添加牛血清白蛋白（BSA）或发情母马血清（EMS）的效果。本研究共使用了分别从繁殖季节和非繁殖季节收集的158个和154个卵巢中分离出的645个卵母细胞。卵母细胞在补充有10% EMS或4 mg/ml BSA的TCM 199中成熟30小时。通过将3%的荧光染料路西法黄溶液注入卵质中来研究卵丘细胞和卵母细胞之间可渗透GJ的存在。在繁殖季节和非繁殖季节收集的卵母细胞之间，未检测到卵母细胞回收效率或卵母细胞减数分裂能力的差异。在繁殖季节收集的绝大多数（90%）卵母细胞与其周围的卵丘细胞具有完全功能性的通讯，但在非繁殖季节收集的卵母细胞中，55.3%的此类通讯被完全中断。在非繁殖季节，在成熟结束时与卵丘细胞通讯被归类为封闭或中间状态的卵母细胞比例，在使用BSA成熟的组中低于使用EMS的组（71.4对97.7，p < 0.05）。在繁殖季节也观察到了相同的趋势，尽管没有统计学意义。在两个季节中，BSA的存在都会导致卵丘扩展不完全。我们的数据表明，在非繁殖季节收集的卵母细胞没有表现出任何减数分裂缺陷，但在从卵巢分离时缺乏与周围卵丘细胞的活跃通讯。目前尚无数据可用于确定对发育能力的影响，尽管其他物种的数据表明可能会有影响。
