Handyside Alan H, Hunter Susan
MRC Experimental Embryology and Teratology Unit, Medical Research Council Laboratories, Woodmansterne Road, SM5 4EF, Carshalton, Surrey, Great Britain.
Rouxs Arch Dev Biol. 1986 Oct;195(8):519-526. doi: 10.1007/BF00375893.
The numbers of cells in the trophectoderm (TE) and inner cell mass (ICM) of mouse blastocysts were counted by differentially labelling their nuclei with two polynucleotide-specific fluorochromes. Blastocysts recovered from the uterus at intervals between their formation early on Day 4 to the initial stages of implantation on day 5 were analysed. TE cell number increase was initially rapid, indicating some synchronisation of the sixth division, but slowed down progressively and plateaued on Day 5, possibly due to the onset of primary giant cell formation. ICM cell number increase was slower than the corresponding TE cells. As a result, TE cell number more than quadrupled, whereas ICM cell number only doubled over this period. Although the mitotic index of both populations of cells fell steadily, there was no significant difference between them. The decline in the proportion of ICM cells, therefore, is likely to be due to cell death, first detected in early blastocysts and predominantly located in the ICM. In addition, however, a contribution of ICM cells to the overlying polar TE cannot be excluded.
通过用两种多核苷酸特异性荧光染料对小鼠囊胚滋养外胚层（TE）和内细胞团（ICM）的细胞核进行差异标记，来计算细胞数量。分析了在第4天早期形成至第5天植入初期不同时间从子宫中回收的囊胚。TE细胞数量最初增加迅速，表明第六次分裂存在一定同步性，但随后逐渐减慢并在第5天趋于平稳，这可能是由于初级巨细胞形成的开始。ICM细胞数量的增加比相应的TE细胞慢。因此，在此期间TE细胞数量增加了四倍多，而ICM细胞数量仅增加了一倍。尽管这两种细胞群体的有丝分裂指数都稳步下降，但它们之间没有显著差异。因此，ICM细胞比例的下降可能是由于细胞死亡，最早在早期囊胚中检测到，且主要位于ICM中。然而，此外，不能排除ICM细胞对上覆极性TE有贡献。
