After Fertilization Implantation Fertilization sperm cell enters the

After Fertilization

Implantation Fertilization (sperm cell enters the oocyte) occurs in the oviduct. The joining of the two cells forms an embryo. Implantation of the embryo occurs in the uterus. Embryo embeds itself in the endometrium several days after fertilization. Pregnancy has now begun.

Implantation starts the production of the hormone HCG (Human Chorionic Gonadotropin) It is found immediately in blood & a few days later in the urine. - detected in pregnancy tests (About one week later) HCG prevents the breakdown of the Corpus luteum. The Corpus luteum produces progesterone that keeps the endometrium from breaking down. FSH and LH production is inhibited which stops any new eggs from being released. Once the placenta will eventually produce its own progesterone & estrogen & the corpus luteum will disintegrate

Birth When the amniotic sac breaks & releases the amniotic fluid (“water breaks”), the baby’s head will press on the cervix Nerve impulses from the cervix signal the brain Brain stimulates the posterior pituitary to release oxytocin (hormone produced by the hypothalamus) Oxytocin causes uterine contractions which push the baby’s head further against the cervix Cycle repeats until baby is pushed through & birthed This is a positive feedback loop