Hormonal Control in Males Hypothalamus GnRH FSH Anterior pituitary Sertoli cells Leydig cells Inhibin Spermatogenesis Testosterone Testis LH Negative feedback – – –

(a) Control by hypothalamus Hypothalamus GnRH Anterior pituitary 1 Inhibited by combination of estradiol and progesterone Stimulated by high levels of estradiol Inhibited by low levels of estradiol 2 FSH LH Pituitary gonadotropins in blood (b) 6 FSH LH FSH and LH stimulate follicle to grow LH surge triggers ovulation 3 Ovarian cycle 8 (c) 7 Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phase Ovulation Luteal phase Estradiol secreted by growing follicle in increasing amounts Progesterone and estradiol secreted by corpus luteum 4 Ovarian hormones in blood Peak causes LH surge (d) 5 Estradiol Progesterone 9 10 Estradiol level very low Progesterone and estra- diol promote thickening of endometrium Uterine (menstrual) cycle Endometrium (e) Menstrual flow phase Proliferative phase Secretory phase Days | | | 15 | | || | – – + Hormonal Control in Females

Control by hypothalamus Inhibited by combination of estradiol and progesterone Stimulated by high levels of estradiol Inhibited by low levels of estradiol Hypothalamus GnRH Anterior pituitary FSH LH Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Ovarian cycle Growing follicle Maturing follicle Corpus luteum Degenerating corpus luteum Follicular phase Ovulation Luteal phase (a) (b) (c) Days | | ||| | || – – + Hormonal Control in Females (Expanded View)

Ovarian hormones in blood Peak causes LH surge Estradiol level very low Estradiol Progesterone Ovulation Progesterone and estra- diol promote thickening of endometrium Uterine (menstrual) cycle Endometrium | | || | | || Days 15 Menstrual flow phase Proliferative phaseSecretory phase (d) (e) Hormonal Control in Females (Expanded View)

Ovary Uterus Endometrium (a) From ovulation to implantation (b) Implantation of blastocyst Cleavage Fertilization Ovulation Cleavage continues The blastocyst implants Trophoblast Inner cell mass Cavity Blastocyst Endo- metrium

Hormones During Pregnancy

Maternal Fetal Blood Flow Placenta Uterus Umbilical cord Chorionic villus, containing fetal capillaries Maternal blood pools Maternal arteries Maternal veins Maternal portion of placenta Fetal arteriole Fetal venule Umbilical cord Fetal portion of placenta (chorion) Umbilical arteries Umbilical vein

Placental Crossing

Fig (a) First Trimester (b) Second Trimester (c) Third Trimester

Fig a (a) First Trimester

Fig b (b) Second Trimester

Fig c (c) Third Trimester

Estradiol Oxytocin from ovaries Induces oxytocin receptors on uterus from fetus and mother’s posterior pituitary Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback + +

3 2 1 Dilation of the cervix Placenta Umbilical cord Uterus Cervix Expulsion: delivery of the infant Uterus Placenta (detaching) Umbilical cord Delivery of the placenta Birthing Process

Fig Placenta Umbilical cord Uterus Cervix Dilation of the cervix 1

Fig Expulsion: delivery of the infant 2

Fig Delivery of the placenta Uterus Placenta (detaching) Umbilical cord 3

MaleFemale Method Event Method Production of sperm Production of primary oocytes Vasectomy Combination birth control pill (or injection, patch, or vaginal ring) Sperm transport down male duct system Oocyte development and ovulation Abstinence Condom Coitus interruptus (very high failure rate) Abstinence Sperm deposited in vagina Capture of the oocyte by the oviduct Tubal ligation Female condom Sperm movement through female reproductive tract Transport of oocyte in oviduct Spermicides; diaphragm; cervical cap; progestin alone (as minipill, implant, or injection) Meeting of sperm and oocyte in oviduct Union of sperm and egg Morning-after pill; intrauterine device (IUD) Implantation of blastocyst in endometrium Methods Of Birth Control

In-Vitro Fertilization

Ethics of In-Vitro Fertilization Advantages of IVF: there are as many reasons for this treatment as there are people seeking this treatment. –over comes infertility –allow families for people who must be sterilised e.g.. radiography/chemo therapy cancer patients Disadvantages of IVF: –what happens to unwanted embryo's –what happens to orphaned embryo's –should infertility be by-passed