When the blastocyst attaches to the wall it is called a ______?*2 pointszygotefetusovumembryo

The correct answer is embryo.

Explanation

The blastocyst is an early stage of human development that forms a few days after fertilization. It consists of an inner cell mass that will eventually develop into the embryo and an outer layer of cells that will form part of the placenta. When the blastocyst successfully implants itself into the uterine wall, this stage of development is referred to as the embryo. This is the crucial transition where the cells begin to differentiate and specialize, leading to the formation of various tissues and organs.

The other terms listed—zygote, fetus, and ovum—refer to different stages or types of cells. The zygote is the fertilized egg before it undergoes cleavage and becomes a blastocyst. The fetus refers to a later stage of development, generally after eight weeks of gestation, while the ovum is the unfertilized egg cell. Therefore, the attachment of the blastocyst is a key moment that marks the beginning of embryonic development.