when egg drops into uteris and is ready to be ferfilized,once a month usually in most woman middle of month,hormone is estrogen....that is E, F is progesterone is secreted,from ovaries, placenta, and adrenal glands ,it gets uteris ready to accept implant and maintain a fertilized egg,the hormone prevents muscle contractions from happening on uteris that would cause a woman's body to reject a fertilized egg..B.....question 1all major system begin to form neural tube which becomes brain and spinal cord digestive system and heart and circulatory system begins to form,the begins of eyes and ears,and tiny limbs call buds appear which will develop into arms an legs....part b question 2 look up on Google this is all I have in my brain....