Reproductive System

Male Reproductive Structures Testes produce sperm Scrotum: sac of skin and smooth muscle that holds testes Maintains testes at a slightly lower temperature Seminiferous tubules within testes: produce sperm Epididymis: sperm become motile and are stored here Ductus (vas) deferens: transports sperm to ejaculatory duct Penis: organ of copulation Contains erectile tissue

Urinary bladder Ductus deferens Penis Testis Scrotum Ejaculatory duct Epididymis Urethra Erectile tissue

Male Reproductive Structures Route of sperm through male reproductive structures Seminiferous tubules Epididymis Ductus deferens Ejaculatory duct Urethra

Accessory Glands Seminal vesicles Prostate gland Secrete fructose and most of seminal fluid Prostate gland Secretes watery alkaline fluid to raise vaginal pH Secretes prostate specific antigen (PSA) to liquefy semen Bulbourethral (Cowper’s) gland Secretes lubricating mucus Cleanses urethra

Seminal vesicle Prostate gland Bulbourethral gland

Seminal vesicle Ductus deferens Prostate gland Bulbourethral gland Urethra Epididymis Testis Penis Uncoiled semi- niferous tubule A posterior view of the reproductive organs and bladder.

Sperm Production Mitosis and meiosis occur in seminiferous tubules Produce large # of haploid sperm Spermatogonia (2n)  primary spermatocyte (2n)  secondary spermatocyte (n)  spermatids (n)  sperm (n) Sertoli cells provide support, nourishment

Tail whiplike movements propel the sperm Midpiece contains mitochondria that produce energy for the sperm Head contains the male’s chromosomes Acrosome contains the enzymes that assist fertilization Illustration of a sperm, showing the head, midpiece, and tail. Figure 16.2d

Testosterone Hormone produced by interstitial cells Function: between seminiferous tubules Function: controls growth/function of male reproductive tissues stimulates aggression and sexual behavior secondary sexual characteristics Determines rate of sperm formation

Testosterone Hormones that regulate testosterone and sperm production LH (from anterior pituitary) stimulates production of testosterone FSH (from anterior pituitary) may enhance sperm formation

Female Reproductive System Ovaries Release oocytes (immature eggs) secrete estrogen and progesterone Oviduct (fallopian tube) Carries oocyte from ovary to uterus Fimbriae help “suck” oocyte into oviduct Fertilization occurs in oviduct Uterus: hollow, pear-shaped organ where fertilized egg grows and develops Cervix – narrow opening into uterus Vagina Organ of sexual intercourse and birth canal

Fimbriae Oviduct Ovary Uterus Cervix Vagina

Female Reproductive System Uterine layers Endometrium: inner lining supports fertilized egg sloughs off during menstrual flow Myometrium: smooth muscle expands during pregnancy, contracts during labor Endometrium Myometrium

Oviduct Fimbriae Ovary Uterus Rectum Urinary bladder Cervix Urethra Vagina Clitoris Anus Sagittal section showing the components of the system in relation to other structures. Figure 16.4a

Female Reproductive System External genitalia Mons pubis Labia majora and minora Clitoris Clitoris Labium minora Labium majora

Mammary Glands Breasts contain mammary glands modified sweat glands Specialized for lactation (production of milk) Hormonal control of lactation: Prolactin – stimulates milk production Oxytocin – stimulates contractions that eject milk

Menstrual Cycle Two linked cycles Ovarian cycle Uterine cycle Changes in ovaries associated with oocyte maturation Controlled by FSH and LH Uterine cycle Changes in endometrial lining of uterus Controlled by estrogen and progesterone

Ovarian Cycle Immature follicle develops; FSH and LH increase Antrum develops within follicle; some estrogen and progesterone secreted Follicle matures (Graafian follicle); antrum enlarges Increasing estrogen causes surge of LH; ovulation occurs Corpus luteum formed from follicle; large amounts of estrogen and progesterone secreted Stimulates growth of endometrium

Ovarian connective tissue Oviduct 1 Immature follicle Ovary Primary oocyte Granulosa cells Uterus 7 Corpus luteum degenerates if pregnancy does not occur 2 Vagina Zona pellucida develops around the primary oocyte 6 Corpus luteum forms from ruptured follicle 3 Fluid-filled antrum develops 5 Ovulation. Follicle ruptures, releasing the secondary oocyte with its polar body and granulosa cells 4 Follicle matures Polar body Secondary oocyte Ovarian connective tissue Figure 16.6

Ovarian Cycle If fertilization and pregnancy occurs Chorion (embryonic tissue) secretes human chorionic gonadotropin (hCG) detected by pregnancy tests hCG causes corpus luteum to produce estrogen and progesterone for another 9–10 weeks After 9–10 weeks, placenta takes over E and P production High levels of E and P prevent ovulation during pregnancy If no fertilization, corpus luteum degenerates

Uterine Cycle Menstrual phase Proliferative phase Days 1–5 E and P decrease Endometrial lining degenerates Menstruation occurs Proliferative phase Days 6–14 E and P increase Endometrial lining proliferates

Uterine Cycle Ovulation Secretory phase Day 14 Days 15–28 Corpus luteum produces E and P Endometrium continues to proliferate Uterine glands mature Uterus is prepared to accept and nourish a fertilized egg

Figure 16.7 LH surge (triggers ovulation) FSH LH LH FSH Hypothalamus Ovarian Cycle Growth of follicle Ovulation Corpus luteum Ovary Progesterone Estrogen Endometrium of uterus Estrogen Progesterone Uterine Cycle Days of one menstrual cycle (28 days, average) 1 Menstrual phase 5 Proliferative phase 14 Secretory phase 28 Figure 16.7

Birth Control Methods Abstinence: not having intercourse Surgical sterilization Vasectomy in males: cut and tie off both ductus deferens Tubal ligation in females: cut and tie off both oviducts

a) Vasectomy. Small incisions are made in the scrotum, and Ductus deferens cut and sealed (both sides) Oviduct tied in two places Uterus Ovary Scrotum a) Vasectomy. Small incisions are made in the scrotum, and each ductus deferens is tied in two places and cut. b) Tubal ligation. An incision is made in a woman’s abdominal wall, the two oviducts are located, and each is tied in two places and cut. Figure 16.10

Birth Control Methods Birth control pills (oral contraceptives) Combination of synthetic progesterone and estrogen Inhibit release of FSH and LH Block ovulation Hormone injections DepoProvera, Lunelle Hormone patch Ortho Evra Vaginal ring NuvaRing

Birth Control Methods IUDs Diaphragms and cervical caps Intrauterine devices Small plastic or metal piece inserted into uterus Mild chronic inflammation prevents fertilization/implantation Diaphragms and cervical caps Prevent sperm from entering the cervix Chemical spermicides Kill sperm cells Condoms Trap ejaculated sperm

Birth Control Methods Natural alternatives Morning-after pills Rhythm method, withdrawal Morning-after pills Prevent pregnancy from continuing Preven, Plan B, Mifeprex (RU-486) Abortion Terminates pregnancy The future Male birth control pill Vaccines for women

Infertility Many causes of infertility Number and quality of sperm < 60 million/ejaculation is considered infertile Pelvic inflammatory disease (PID) Scarred, blocked oviducts Abnormal production of FSH, LH Irregular menstrual cycles Endometriosis Decreased reproductive capacity with age Miscarriage (spontaneous abortion)

Enhancing Fertility Artificial insemination In vitro fertilization (IVF) Fertilization in test tube outside of the body GIFT (gamete intrafallopian transfer) Unfertilized eggs and sperm placed directly in oviduct ZIFT (zygote intrafallopian transfer) Fertilized egg is placed in oviduct

Sexually Transmitted Infections (STIs) Transmitted by sexual contact: Genital, oral-genital, anal-genital Bacterial Gonorrhea, syphilis, chlamydia Viral HIV, hepatitis B, genital herpes, HPV Other Yeasts (Candida), protozoan (Trichomonas), arthropod (pubic lice)

400 Gonorrhea 300 Rate (per 100,000 population) 200 Chlamydia 100 Syphilis 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year Figure 16.14

3000 2500 2000 Cases per 100,000 population 1500 1000 500 10-14 15-19 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-54 55-64 65+ Age group Figure 16.15

Sexually Transmitted Infections (STIs) Prevention strategies Choose partner wisely Communicate Use suitable barriers Get tested and treated Get vaccinated