1)secretions from which of the following structures are required before implantation can occur? a)ovarian follicle b)pituitary gland c)corpus luteum d)all of these 2)hCG is different from other gonadotrophic hormones because it a)is produced by the hypothalamus b)is not produced by a female endocrine gland c)does not stimulate andy tissue in the body d)does not enter the blood stream