Humans are sexually reproducing and viviparous. The reproductive events include gametogenesis, insemination, fertilisation, implantation, gestation and parturition.
Male system: a pair of testes (in the scrotum, kept 2-2.5 degrees C below body temperature), accessory ducts (rete testis, vasa efferentia, epididymis, vas deferens), accessory glands (seminal vesicles, prostate, bulbourethral glands) and the penis. Each testis has ~250 lobules, each with 1-3 seminiferous tubules lined by spermatogonia and Sertoli cells; Leydig cells outside the tubules secrete androgens.
Female system: a pair of ovaries (produce ovum and ovarian steroid hormones), oviducts (infundibulum-ampulla-isthmus), uterus (perimetrium, myometrium, endometrium), cervix, vagina, external genitalia and mammary glands.
Gametogenesis: spermatogenesis (from puberty) gives four equal sperms; oogenesis (begins in embryonic life) gives one ovum plus polar bodies via unequal divisions.
Menstrual cycle (~28/29 days): menstrual, follicular, ovulatory and luteal phases, regulated by GnRH, FSH, LH, estrogen and progesterone; the LH surge triggers ovulation.
Fertilisation occurs in the ampulla, forming a diploid zygote (sex determined by the sperm). Cleavage forms a morula then blastocyst (trophoblast + inner cell mass), which implants in the endometrium. The placenta supports the foetus and secretes hCG, hPL, estrogens, progestogens; relaxin comes from the ovary. Parturition is driven by oxytocin; lactation begins with colostrum.