NOTES: CH 46 – Animal Reproduction (part 1)

MALE REPRODUCTIVE SYSTEM

Functions:

1) Produce sperm;

2) Deliver sperm to female repro. tract;

3) 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 SYSTEMAccessory glands

(continued):

2) PROSTATE GLAND:● secretes thin, milky, slightly alkaline fluid;● fluid helps to balance the pH environment of the vagina.

MALE REPRODUCTIVE SYSTEMAccessory 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:

1) Produce egg cells;

2) Produce female hormones;

3) 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:

SPERMATOGENESIS:● 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:

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