核仁是细胞中合成 r RNA的场所 ,与细胞的蛋白质合成密切相关。近年的研究证明 ,在卵子发生和早期胚胎发育过程中 ,核仁的结构和机能都发生着有规律的变化 ,对于研究卵子发生和早期胚胎发育机理有着重要的意义。本文以牛为主要对象 ,综述了有关核仁的结构、发生以及卵母细胞成熟及早期胚胎发育过程中核仁结构和 r
Most porcine oocytes used in studies on embryo biotechnology and the in vitro production of embryos are currently obtained from the ovaries of slaughtered gilts. The duration and temperature during ovary transportation and handling might, therefore, affect the recovery of culturable COCs, chromatin configuration and developmental competence of oocytes. The effects of ovary storage temperature on chromatin configuration and in vitro maturation of porcine oocytes were examined in this study. Ovaries collected from a slaughterhouse were stored in vitro for 8 h under different temperatures. The results showed that more culturable COCs were isolated from the ovares stored at 39℃ than that from ovaries stored at 31℃ or 20℃ and before storage. Thirty-one centidegree was the best storage temperature in terms of cumulus expansion, nuclear maturation and morphology of the first polar body after in vitro maturation culture. The ability of cumulus expansion was completely lost in COCs derived from ovaries stored at 39℃for 8 hours. Ovary storage (at both 31℃ and at 20℃) increased the proportion of oocytes with the GVc configuration in which chromatin condensed into a single big clump at the nucleolus and the functional significance of this configuration needs further investigations.
It was shown that expansion of porcine cumulus did not depend on oocyte-secreted factor(s), and it is therefore presumed that porcine CEEF may not be produced exclusively by the oocyte. In this experiment, we used mouse oocytectomized complexes (OOX), which were incapable of CEEF production, to assess the secretion of CEEF by evacuated zona, oocytes of different quality and somatic cells in the porcine follicles. The results showed that: (i) Evacuated zonae from both porcine and mouse oocytes did not produce CEEF. (ii) Porcine oocytes of A, B and C types from 3-6 mm follicles were not significantly different in both production and activity of CEEF. (iii) Both porcine OOX from 3-6 mm follicles and granulose cells from < 1 mm follicles secreted CEEF in a large quantity, independent of gonadotro-pins; mural granulose cells from 3-6 mm follicles, however, produced neglectable amount of CEEF. (iv) The follicular fluid from 3-6 mm porcine follicles contained CEEF activity that was concentration-dependent,
SUN XingshenYUE KuizhongMA SuofengYI YalingZOU YiTAN Jinghe
