Hansel W
J Reprod Fertil Suppl. 1981;30:231-9.
Results of a detailed study involving 18 pregnant, 17 cyclic and 12 inseminated but non-pregnant Holstein heifers indicated the following. (1) Jugular plasma progesterone concentrations were higher (P less than 0.05) in pregnant than in cyclic or in inseminated--non-pregnant animals from Days 10 through 18. (2) Jugular plasma progesterone concentrations of inseminated--non-pregnant animals could be related to heifers in which (a) fertilization may not have occurred (N = 5); (b) embryonic death may have occurred between Days 6 and 9 (N = 5); and (c) embryo mortality may have occurred shortly before Day 18 (N = 2). (3) Jugular plasma oestradiol concentrations were higher (P less than 0.05) in pregnant than in cyclic animals between Days 10 and 18; the oestrogen values of the inseminated--non-pregnant animals resembled those of the pregnant animals. (4) The steroid-synthesizing capabilities of incubated luteal tissues from inseminated--non-pregnant heifers more closely resembled those of tissues from pregnant animals than those of cyclic animals. (5) At Day 18 PGF concentrations in endometrial and luteal tissues and ovarian arterial plasma did not differ among the 3 groups. (6) PGF and progesterone concentrations of luteal tissues were negatively correlated (r = -0.77, P less than 0.05) in cyclic animals and positively correlated (r = 0.73, P less than 0.05) in pregnant animals, implying a luteotrophic effect of PGF in pregnant animals. These results suggested a luteotrophic effect of the embryo, beginning as early as Day 10 of pregnancy, and the results of further experiments suggested that (i) homogenates and extracts of Day 18 bovine embryos contain one or more substances capable of stimulating progesterone synthesis in dispersed bovine luteal cell preparations; (ii) the luteotrophic activity was proportional to the protein contents of the embryo homogenates; and (iii) the luteotrophic activity was heat labile and was removed from homogenates by dialysis, indicating a structure of one or more relatively small molecules.
一项针对18头怀孕、17头处于发情周期以及12头已授精但未怀孕的荷斯坦小母牛的详细研究结果如下：(1) 从第10天到第18天，怀孕小母牛的颈静脉血浆孕酮浓度高于发情周期或已授精但未怀孕的小母牛（P<0.05）。(2) 已授精但未怀孕小母牛的颈静脉血浆孕酮浓度可能与以下情况有关：(a) 可能未发生受精的小母牛（N = 5）；(b) 在第6天至第9天之间可能发生胚胎死亡的小母牛（N = 5）；(c) 在第18天前不久可能发生胚胎死亡的小母牛（N = 2）。(3) 在第10天至第18天之间，怀孕小母牛的颈静脉血浆雌二醇浓度高于发情周期的小母牛（P<0.05）；已授精但未怀孕小母牛的雌激素值与怀孕小母牛的相似。(4) 已授精但未怀孕小母牛的培养黄体组织的类固醇合成能力与怀孕动物组织的更相似，而与发情周期动物组织的不同。(5) 在第18天，三组动物的子宫内膜、黄体组织和卵巢动脉血浆中的PGF浓度没有差异。(6) 发情周期动物黄体组织中的PGF和孕酮浓度呈负相关（r = -0.77，P<0.05），而怀孕动物中呈正相关（r = 0.73，P<0.05），这意味着PGF对怀孕动物有黄体营养作用。这些结果表明，胚胎的黄体营养作用早在怀孕第10天就开始了，进一步实验结果表明：(i) 第18天牛胚胎的匀浆和提取物含有一种或多种能够刺激分散的牛黄体细胞制剂中孕酮合成的物质；(ii) 黄体营养活性与胚胎匀浆的蛋白质含量成正比；(iii) 黄体营养活性对热不稳定，可通过透析从匀浆中去除，表明其结构为一种或多种相对较小的分子。
