Heap R B, Hamon M, Allen W R
J Reprod Fertil Suppl. 1982;32:343-52.
Aromatase activity measured by the incorporation of [3H]androstenedione into unconjugated and conjugated oestrogens was detectable in the equine conceptus during early pregnancy. Activity was substantially higher in yolk sac compared to allantochorion between Days 20 and 52 after ovulation. Oestrone sulphate concentrations in yolk-sac fluid measured by radioimmunoassay increased markedly to reach values of about 3 micrograms/ml at Day 36, approximately 10-fold higher than those in allantoic fluid. Extra-embryonic membranes in a 28-day conceptus all contained aromatase (chorionic girdle greater than trilaminar omphalopleure greater than bilaminar omphalopleure greater than allantochorion), implying that the enzyme complex was present in trophoblast and/or endoderm rather than mesoderm. Aromatase activity in chorionic girdle cells was low before their migration into the endometrium. Endometrial tissue contained substantial sulphotransferase and glucuronidase activity. The ability of the preimplantation equine conceptus to synthesize oestrogens was strikingly similar to that found previously in the pig; in both species the allantochorionic placenta is non-invasive.
在妊娠早期的马胚胎中，通过检测[3H]雄烯二酮掺入未结合和结合雌激素的情况来测定芳香化酶活性。在排卵后第20至52天期间，卵黄囊中的活性显著高于尿囊绒毛膜。通过放射免疫测定法测得的卵黄囊液中硫酸雌酮浓度在第36天显著增加，达到约3微克/毫升，约为尿囊液中浓度的10倍。28天胚胎的胚外膜均含有芳香化酶（绒毛膜带大于三层卵黄囊大于双层卵黄囊大于尿囊绒毛膜），这意味着该酶复合物存在于滋养层和/或内胚层而非中胚层。绒毛膜带细胞在迁移到子宫内膜之前，其芳香化酶活性较低。子宫内膜组织含有大量的磺基转移酶和葡萄糖醛酸酶活性。植入前马胚胎合成雌激素的能力与先前在猪中发现的情况惊人地相似；在这两个物种中，尿囊绒毛膜胎盘均无侵袭性。
