The Stage at Which a Pre-Embryo is a Solid Mass

Question

The stage at which a pre-embryo is a solid mass of cells and enters the uterus is the
A)trophoblast.
B)zygote.
C)blastocyst.
D)morula.

Accepted Answer

At this stage, the pre-embryo is called a morula, which is a solid mass of cells that has not yet formed a cavity. It consists of around 16 cells that have undergone several rounds of cell division. The morula enters the uterus around day 4 to 5 after fertilization and begins the process of implantation, which involves the formation of a cavity within the morula to form a blastula. Therefore, options A, B, and C are incorrect because they refer to other stages of early embryonic development.