A woman has conceived and implantation has occurred in her uterus. Explain the sequence of changes upto parturition which take place within her body.

Explanation

After implantation the chorionic villi and uterine tissue become interdigitated to form placenta. Placenta facilitates supply of `O_2` and nutrients to the embryo and removes `CO_2` and excretory materials produced by the embryo. Increased production of hormones like estrogen, progesterone, prolactin are essential for supporting foetal growth, metabolic changes in the mother and maintenance of pregnancy. The inner cell mass differentiates into three distinct germ layers mesoderm, ectoderm and endoderm) which given rise to all tissues (organs) in adults After one month of pregnancy the embryo's heart is formed By the end of the second month of pregnancy the foetus develops limbs and digits. By the end of 12 weeks (first trimester) most of the major organ systems are formed.By the end of 24 weeks (second trimester) the body is covered with fine hair. eyelids separate and eyelashes are formed. The signals for parturition originate from the fully developed foetus and the placenta which induce mild uterine contractions called foetal ejection reflex The triggers release of oxytocin from maternal pituitary along with stimulatory reflex resulting in stronger contractions leads to parturition.