A woman has conceived & implantation has occurred within her uterus. Discuss the sequence of changes up to parturition which will take place within her body under the influence of various hormones.
The following changes take place in the body of women after implantation:- The trophoblast differentiates into two layers; the outer layer secretes enzymes to dissolve the endometrium of the uterus. The inner layer grows out as finger-like projections called chorionic villi into the uterine stroma. The chorionic villi & the uterine tissue become interdigitated to form a structural & functional unit called the placenta. Placenta secretes hormones like HCG, HPL, estrogen & progesterone that are necessary to maintain pregnancy The umbilical cord, the structure that connects the placenta with the fetus is formed. Simultaneously, inner cell mass differentiates into an outer layer called ectoderm & an inner layer called endoderm. & a middle layer called mesoderm appears between ectoderm & endoderm. The primary germ layers give rise to all the tissues & organs of the adults e.g. after one month the heart is formed & after the second month the digits & limbs are formed. By the end of the ninth month of pregnancy, the foetus is completely developed & is ready for delivery. During parturition, the ovary secretes a hormone called relaxin that facilitates parturition which softens the connective tissue. Mild contraction called foetal ejection reflex is induced. This triggers the release of oxytocin from the posterior pituitary. Oxytocin induces stronger leads to the expulsion of the baby from the uterus, through the birth canal.
