Naeslund G
Ups J Med Sci. 1979;84(1):9-20. doi: 10.3109/03009737909179136.
To estimate the degree of trophoblast outgrowth in vitro, mouse blastocysts obtained after delay of implantation were cultured either in a modified Brinster medium or in the same medium with exclusion of various combinations of glucose, arginine and leucine. Trophoblast outgrowth was prevented only in a medium from which all three substances were excluded. In this medium the blastocysts remained expanded for 5 days without signs of trophoblast outgrowth--a growth arrest in vitro. After transfer of blastocysts growth arrested in vitro for 5 days to a complete medium including both glucose and the two amino acids, normal outgrowths occurred within two or three days. The growth-arrested blastocysts also developed normally for at least one week when transplanted into salpingectomized foster mothers. It is concluded that blastocysts activation in vitro can be controlled by a few nutrients in a way reminiscent of the activation prior to implantation in utero. Blastocysts activated in utero by systemic administration of oestrogen for various lengths of time before the start of culture, or in vitro by preincubation in a medium containing glucose and all amino acids, also grew out in the growth arrest medium if they had been activated for a sufficiently long time, 18 h in utero and 1 h in vitro, thus indicating that when a blastocyst has reached a certain degree of activation its growth can not be arrested by exclusion of glucose, arginine and leucine.
为评估体外滋养层细胞生长程度，将延迟着床后获得的小鼠囊胚在改良布林斯特培养基中培养，或在排除葡萄糖、精氨酸和亮氨酸不同组合的相同培养基中培养。仅在排除所有这三种物质的培养基中，滋养层细胞生长才受到抑制。在这种培养基中，囊胚可保持扩张状态5天，而无滋养层细胞生长迹象——即体外生长停滞。将体外生长停滞5天的囊胚转移至包含葡萄糖和两种氨基酸的完全培养基后，两到三天内即可出现正常生长。将生长停滞的囊胚移植到输卵管切除的代孕母鼠体内时，它们也至少能正常发育一周。结论是，体外囊胚激活可由几种营养物质控制，这类似于子宫内着床前的激活方式。在培养开始前通过全身注射雌激素在子宫内激活不同时长的囊胚，或在含有葡萄糖和所有氨基酸的培养基中进行体外预孵育激活的囊胚，如果激活时间足够长（子宫内18小时，体外1小时），在生长停滞培养基中也能生长，这表明当囊胚达到一定激活程度时，其生长不会因排除葡萄糖、精氨酸和亮氨酸而被抑制。
