NOTES: CH 46 – Animal Reproduction (part 1)

MALE REPRODUCTIVE SYSTEM Functions: Produce sperm; Deliver sperm to female repro. tract; Produce androgens (male sex hormones).

MALE REPRODUCTIVE SYSTEM - Anatomy ● TESTES -develop in abdomen; descend into scrotum before birth; -made up of tightly coiled tubes (SEMINIFEROUS TUBULES) where sperm are formed; -scattered between tubules are the LEYDIG CELLS (produce testosterone and other androgens).

(Leydig cells) TESTIS

● SCROTUM: -a pouch of skin that encloses the testes for protection and temperature regulation

MALE REPRODUCTIVE SYSTEM - Anatomy ● EPIDIDYMIS -6 meters of tubes; sperm cells are here for approx. 20 days; -location where sperm become motile, gain ability to fertilize.

MALE REPRODUCTIVE SYSTEM - Anatomy ● VAS DEFERENS (muscular tube) ● EJACULATORY DUCT ● URETHRA -tube that drains both repro. & excretory products

MALE REPRODUCTIVE SYSTEM - Anatomy ● PENIS -3 cylinders of erectile tissue (when filled with blood, penis becomes erect); -head of penis = glans penis; has thinner covering; is covered by foreskin.

MALE REPRODUCTIVE SYSTEM There are 3 sets of accessory glands (add secretions to semen): 1) SEMINAL VESICLES (2): ● produce 60% of semen volume/fluid; ● fluid contains mucus, fructose sugar (energy!), coagulating enzyme, prostaglandins.

MALE REPRODUCTIVE SYSTEM Accessory glands (continued): 2) PROSTATE GLAND: ● secretes thin, milky, slightly alkaline fluid; ● fluid helps to balance the pH environment of the vagina.

MALE REPRODUCTIVE SYSTEM Accessory glands (continued): 3) BULBOUREHTRAL GLANDS (2): ● secrete viscous mucus PRIOR to ejaculation ● fluid neutralizes any acidic urine in the urethra; ● carries some sperm; ● a.k.a. Cowper’s glands.

SEMEN ● consists of: sperm cells and secretions from the seminal vesicles, prostate gland, bulbourethral glands *typical semen production = 2-5 mL; *semen first coagulates; then thins & sperm begin to swim through the female reproductive tract…

FEMALE REPRODUCTIVE SYSTEM Functions: Produce egg cells; Produce female hormones; Nurture & protect developing fetus.

FEMALE REPRODUCTIVE SYSTEM - Anatomy ● OVARIES: -about size & shape of almonds -contains many FOLLICLES…

The follicles… *surround, nourish, protect egg cells; *produce estrogens; *mature and release egg during monthly cycle (1 follicle per month, starting at puberty and ending at menopause)…this is OVULATION; *each becomes a CORPUS LUTEUM following ovulation; *disintegrate if egg is not fertilized.

FEMALE REPRODUCTIVE SYSTEM - Anatomy ● OVIDUCTS (“FALLOPIAN TUBES”): -cilia “pull” the egg cell in and convey the egg down the duct; -fertilization occurs HERE!!! ● UTERUS (“womb”): -thick, muscular organ; expands du ring pregnancy; -inner lining = ENDOMETRIUM, which contains many blood vessels

FEMALE REPRODUCTIVE SYSTEM - Anatomy ● CERVIX (neck of uterus) ● VAGINA (birth canal) -thin-walled chamber where sperm are deposited; -hymen = vascularized membrane which covers vaginal opening from birth until it is ruptured

FEMALE REPRODUCTIVE SYSTEM - Anatomy ● BARTHOLIN’S GLANDS -small glands near vaginal opening; -secrete mucus during sexual arousal response. ● LABIA MINORA / LABIA MAJORA -enclose and protect vaginal opening / urethral opening

Sexual Response: Two types of physiological reactions predominate in both sexes during sexual arousal/response: ● Vasocongestion: filling of a tissue with blood ● Myotonia: increased muscle tension

GAMETE PRODUCTION: ● Spermatogenesis: production of sperm cells ● Oogenesis: development of ova -see figures 46.12 (pg. 1006-1007)

Differences between spermatogenesis & oogenesis: ● All 4 meiotic products develop into mature sperm ● Sperm cells continue to develop throughout a male’s life ● Stages of meiosis occur continuously, in an uninterrupted sequence

Differences between spermatogenesis & oogenesis: ● Uneven cytokinesis; most cytoplasm goes to 2° oocyte (becomes ovum); the other products (polar bodies) disintegrate ● Female is born with all of her egg cells ● Has long “resting” periods of meiosis