Copp A J
J Embryol Exp Morphol. 1978 Dec;48:109-25.
Increase in cell number has been compared with mitotic activity in the polar and mural trophectoderm and in the inner cell mass (ICM) of mouse blastocysts. The results indicate that whereas ICM cells divide at a rate which is compatible with the rate of increase of ICM cell number, polar trophectoderm cells divide faster and mural trophectoderm cells slower than can account for their own rates of cell number increase. It is suggested that the ICM induces a high rate of proliferation in the polar trophectoderm and that there is a resulting cell shift from polar to mural regions during blastocyst development. Mural trophectoderm cells close to the ICM divide faster than those farther away, indicating that cells may retain a 'memory' of ICM contact for some time after leaving the ICM. There is considerable cell death in the blastocyst, but this is restricted to a short period of time coincident with the appearance of primitive endoderm.
已将细胞数量的增加与小鼠囊胚的极滋养外胚层、壁滋养外胚层和内细胞团(ICM)中的有丝分裂活性进行了比较。结果表明,虽然ICM细胞的分裂速度与ICM细胞数量的增加速度相符,但极滋养外胚层细胞的分裂速度比壁滋养外胚层细胞快,而壁滋养外胚层细胞的分裂速度比其自身细胞数量增加的速度慢。有人提出,ICM诱导极滋养外胚层的高增殖率,并且在囊胚发育过程中会发生从极区到壁区的细胞转移。靠近ICM的壁滋养外胚层细胞比远离ICM的细胞分裂得更快,这表明细胞在离开ICM后的一段时间内可能会保留与ICM接触的“记忆”。囊胚中存在相当数量的细胞死亡,但这仅限于与原始内胚层出现同时发生的短时间内。