Kuz'mina T I, Lebedeva I Iu, Torner H, Alm H
Russian Research Institute of Farm Animal Genetics and Breeding, Moskovskoe Shosse 55a, Pushkin, St. Petersburg, 189620 Russia.
Ontogenez. 2001 Mar-Apr;32(2):140-7.
We studied the influence of bovine prolactin on the maturation of cumulus-enclosed bovine oocytes in different culture systems as well as on their capacity for subsequent development after in vitro fertilization. The prolactin effect on chromosome transformations in oocytes depended on the hormone concentration in the medium with fetal calf serum. Prolactin at 50 ng/ml proved to stimulate nuclear maturation of the oocytes. This concentration was used to compare various systems of oocytes cultivation. The prolactin effect on bovine oocytes maturation and their capacity for subsequent development depended on the composition of the cultivation medium. The introduction of prolactin into the medium with fetal calf serum, estradiol, and follicle-stimulating hormone had no effect on the reinitiation of meiosis in the oocytes but stimulated its completion, which increased the proportion of the oocytes at the telophase I and metaphase II stages as well as the proportion of the eggs cleft after fertilization. Prolactin affected neither the nuclear maturation nor the capacity for further development of the oocytes cultivated in the medium with serum of estrous cows. The addition of prolactin to the medium with calf serum where the oocytes and granulosa cells were cocultured increased the subsequent yield of the embryos developed to the morula and blastocyst stages. In this culture system, the hormone did not affect the rate of oocytes that reached the final stages of meiosis but inhibited their transition from telophase I to metaphase II. We propose that prolactin may favor the completion of cytoplasmic modifications going into the maturing oocyte.
我们研究了牛催乳素对不同培养系统中卵丘包裹的牛卵母细胞成熟的影响，以及对其体外受精后后续发育能力的影响。催乳素对卵母细胞染色体转化的作用取决于含有胎牛血清的培养基中激素的浓度。50纳克/毫升的催乳素被证明能刺激卵母细胞的核成熟。该浓度用于比较各种卵母细胞培养系统。催乳素对牛卵母细胞成熟及其后续发育能力的影响取决于培养基的组成。在含有胎牛血清、雌二醇和促卵泡激素的培养基中添加催乳素对卵母细胞减数分裂的重新启动没有影响，但能刺激其完成，这增加了处于第一次减数分裂末期和第二次减数分裂中期的卵母细胞比例以及受精后分裂的卵子比例。催乳素对在发情期奶牛血清培养基中培养的卵母细胞的核成熟和进一步发育能力均无影响。在卵母细胞与颗粒细胞共培养的含有小牛血清的培养基中添加催乳素，增加了发育到桑椹胚和囊胚阶段的胚胎的后续产量。在这种培养系统中，该激素不影响达到减数分裂最后阶段的卵母细胞的比例，但抑制它们从第一次减数分裂末期向第二次减数分裂中期的转变。我们认为催乳素可能有利于成熟卵母细胞细胞质修饰的完成。
