Module 2 page 5 - GRLContent

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• day 8, the blastocyst arrives in the uterus and implants in the endometrium becoming an embryo. This ends the germinal period and begins the embryonic period of prenatal development.

• pregnancy does not occur until the Conceptus undergoes rapid cell division and implants into the uterine lining

• After fertilization

• When sperm and egg unite, a Zygote is formed

• the zygote divides into two cells, then four, then eight . . . and so forth.

• By the third day, a small, hollow ball of 32+ cells has grown.

• cluster of cells within the blastocyst will develop into the body and the outer layers will become supporting structures, such as the amniotic sac and placenta, during gestation .

• same time that pregnancy can be detected.

• key processes in prenatal development beyond cell division and replication: folding, instruction, death, and migration

• When cells at specific locations cause tissue to bend, the folding results in complex shapes

• Cell instruction refers to chemical signals that tell cells where they are and what they are to do relative to other cells

• When certain cells are killed, body structures are refined (e.g., cells between fingers and toes;

• Cells also reorganize by migrating or traveling to different areas (e.g., brain; Polleux & Anto

• Highlights of prenatal development