Review Sheet B Test #1 Biology 2213 Dr. James Adams
Reproductive System and Development
THE REPRODUCTIVE SYSTEM -- Chapter 27
Two Major Functions of the primary sex organs -- the gonads (testes/ovaries):
1. Production of gametes
2. Secretion of hormones
Reproductive System Anatomy -- refer to your lab practical
"Structures to Know" sheet; you
are responsible for knowing the epithelial linings/muscle in the walls of the various organs
MALE -- Know the following structures and their general functions:
Gonads and coverings
1. Scrotum, with dartos muscle (part of external genitalia)
2. Testes (testicles) -- tunica vaginalis/albuginea, lobules with seminiferous tubules/interstitial cells,
rete testis (see below* for more details on the seminiferous tubules)
1. Epididymis -- storage/maturation of sperm; can be stored for several months
2. Spermatic Cord -- vas deferens, testicular arteries/veins (pampiniform plexus), cremaster
muscle; passes through inguinal canal into abdominal cavity
3. Vas deferens joins ejaculatory ducts (from Seminal vesicles, see below)
4. Urethra -- prostatic, membranous, penile
Penis (part of external genitalia) with prepuce (foreskin)
1. Erectile tissue -- corpora cavernosa (two) with crura; corpus spongiosum (one, around
urethra) with bulb (root)/glans
2. Bulbospongiosus muscles
1. Seminal vesicles -- produce 60% of semen volume; alkaline secretions include fructose and
prostaglandins (muscle contraction stimulant in female reprod. tract)
2. Prostate Gland -- produces about 30% of semen volume; secretions include PSA and sperm-
3. Bulbourethral (or Cowper=s) Glands -- secretions are pre-climactic; cleanse the urethra
Semen is a combination of testicular fluid (produced by sustentacular cells), sperm and secretions of
the accessory glands, and includes some antibiotic chemicals as well. One ejaculatory event releases
about 2 - 5 ml of semen, containing between 100 and 500 million sperm.
Male Sexual Response -- Two events:
1. Erection -- a parasympathetic event. Stimulation (various) causes release of NO which
dilates penile arteries, in turn delivering blood to erectile tissues; compresses penile veins.
2. Ejaculation (orgasm/climax) -- a powerful sympathetic event, with effects reaching well
beyond the reproductive tract. Involves peristaltic waves along the duct system, expulsion of
materials from accessory glands, constriction of internal urethral sphincter, and contraction of
the penile bulbospongiosus muscles. Followed by variable in length latent period.
Spermatogenesis -- Meiosis in males; as cells divide, move toward the lumen of the seminiferous
tubules; meiosis reduces the chromosome number from diploid (2N=46) to haploid
(1N=23), and is really two divisions, with the first division being the reduction division.
*Takes place In Seminiferous Tubules: Spermatogonia º Primary spermatocytes (2N) º
Secondary spermatocytes (1N) º spermatids º sperm(-atozoa) -- four functional (but
immature) sperm released in lumen; takes around 70 days. Head (with acrosome/nucleus),
midpiece (with mitochondria), and tail.
Sustentacular cells: several roles
1. Produce testicular fluid
2. Absorbs sloughed off materials from spermatids
3. Forms blood-testis barrier; tight junctions keep genetically unique sperm isolated from the
4. Release ABP (Androgen-binding Protein) in response to FSH
5. Also release inhibin
1. FSH targets Sustentacular Cells to release ABP; LH (also called ICSH -- interstitial cell
stimulating hormone) targets interstitial cells to release testosterone
2. ABP picked up by spermatogonia; the ABP allows the spermatogonia to respond to
testosterone by initiating meiosis
3. Testosterone (and inhibin) balances its own release (and sperm production) through
negative feedback to hypothalamus (GnRH) and the anterior pituitary (FSH and LH)
Development of Sexual Characteristics: Primary (enlargement/maturation of sex organs) and
secondary (muscle/bone mass, hair growth, voice, etc.). Puberty represents a decrease in
sensitivity of the hypothalamus to testosterone; actual mechanism not clear.
FEMALE -- Know the following structures and their general functions:
Gonads and attachments/coverings:
1. Ovaries with tunica albuginea
2. Ovarian/suspensory ligaments
3. Mesovarium (Mesentery of the ovary; part of the
1. Fallopian (Uterine) Tubes (or oviducts), with fimbriae, isthmus, mesosalpinx.
1. Main parts: body, fundus, isthmus, cervix
2. Broad/round ligaments.
3. Layers of wall:
a. Perimetrium (peritoneal lining around uterus)
b. Myometrium (thick [smooth] muscle in wall)
c. Endometrium with stratum basalis/functionalis and spiral arteries.
Vagina, with fornices around cervix
External genitalia (vulvae, pudendum):
1. Clitoris, with erectile tissue (corpora cavernosa)
2. Labia minora/majora with clitoral hood (prepuce)
3. Vestibular glands
4. Mons pubis
Mammary glands -- READ, and know general information about breast cancer; not actually
part of reproductive system, but won't be in use unless reproductive system has been active!
Oogenesis - Meiosis in females; process partially completed within follicles in ovaries, completed
Oogonia º Primary oocytes (2N; at birth) º Secondary oocytes (1N; at ovulation) º
Ovum (only after fertilization)
Only one functional ovum produced, due to unequal cytokinesis during meiosis; three polar
bodies also produced.
The Ovarian/Uterine Cycles and Hormonal Regulation of the Cycles:
The hypothalamus (GnRH)/anterior pituitary (FSH/LH) control the ovarian cycle, which in turn
controls the uterine cycle with the ovarian hormones (estrogen/progesterone).
Ovarian Cycle: Rising FSH stimulates development of primordial follicle through primary/
secondary follicle to mature (Graafian/Vesicular) follicle (surrounded by theca folliculi); during
this process primary oocyte develops into secondary oocyte (which is ovulated). Follicle cells
become granular, releasing estrogen which initially inhibits FSH and therefore more follicle
development, but estrogen levels reach a critical level and initiate a positive feedback loop with
LH release from Ant. Pit. The peak of LH causes ovulation, and also conversion of remaining
granulosal cells into corpus luteum, which in turn starts releasing progesterone. Assuming no
fertilization, progesterone shuts off LH production which in turn cause atrophy of the corpus
luteum (into corpus albicans -- scar tissue).
Uterine (Menstrual) Cycle: Estrogen release from developing follicle stimulates proliferative phase
of endometrium (growth/maturation of stratum functionalis); after ovulation, progesterone ("for
gestation" --the hormone of pregnancy) stimulates the secretory phase of the endometrium
(ready for implantation); with degeneration of the corpus luteum, the spiral arteries spasm and
Development of Primary/Secondary Sexual Characteristics: As with male, hypothalamus decreases
in sensitivity to female hormones at puberty. With maturation of sex organs, and development of
breasts, etc., puberty involves the first menstruation (menarche) and establishment of the cycle.
Female Sexual response: as with male, involves excitation by various stimuli (a parasympathetic
event with increased blood flow to clitoris, walls of vagina, and breasts, and increased secretions
from cervical/vestibular glands for lubrication), followed by climax or orgasm (a sympathetic
event with muscular contractions [reverse peristalsis] of reproductive tract, and muscular
contractions in other parts of the body and pleasurable sensations). Typically, no latent period
necessary, and female can enter directly into new excitement phase.
Sexually Transmitted Diseases -- read and know general characteristics of each, including most
commonly transmitted bacterial/viral (chlamydia/herpes)
Development of Male vs. Female Structures (ovary = testis; clitoris = penis; scrotum = labia majora)
Menopause -- Events of (reasons for masculinization; loss of bone mass)
Fertilization to Birth; conceptus passes from zygote through embryonic stage through fetal stage.
I. Embryonic stage: from fertilization to gastrulation (first two weeks)
Fertilization -- involves sperm capacitation (degradation of acrosomal membrane)
Several hundred sperm necessary to digest path through layers of cells and zona pellucida
Prevention of polyspermy -- one sperm cell reaches and penetrates the secondary oocyte
membrane; at this point, two events occur to prevent second penetration:
1. Fast Block -- depolarization event like first half of action potential; "zaps" sperm
2. Slow Block -- also fast, cortical reaction. Calcium channels open, calcium enters and cause
cortical granules to release materials and form fertilization membrane.
2° oocyte completes second meiotic division, forming ovum briefly before nuclei fuse.
Cleavage divisions: zygote to morula to blastocyst (with trophoblast, inner cell mass, cavity w/ fluid)
Trophoblast -- contribution to placenta; forms chorion, which releases human chorionic
gonadotropin (hCG),which is identical in function to LH and retains corpus luteum
(progesterone secretion), and therefore placenta, for first trimester (at which point, placenta
produces own estrogen and progesterone). Upon implantation, forms syncytiotrophoblast
which, in turn, develops chorionic villi bathed in by maternal blood (in lacunae) for exchange
of wastes from and nutrients to developing conceptus; cytotrophoblast remains immediately
around developing conceptus
Inner Cell Mass -- further differentiates to form blastodisc, with two membranous sacs inside
chorion, the amnion (on ectodermal side) and yolk sac (on endodermal side)
Blastodisc -- double-layered (ectoderm/endoderm) goes through gastrulation, where cells
of the ectoderm divide and migrate in between the two existing layers, forming mesoderm.
Establishment of three primary tissue layers ends gastrulation and begins the embryonic stage.
Organogenesis (gastrulation through formation of all organ systems; weeks 3-8)
The reason why gastrulation is considered so monumental is that the origin of any tissue/organ can
be traced back to one of the three primary tissue layers. Not long after gastrulation, entire
blastodisc "folds over" on itself, both along sides and end to end, engulfing much of the yolk sac,
forming the initial gut lining and extending the ectoderm (and amnion) around the entire outside.
Early events in organogenesis: formation of notochord (in mesoderm)
Chemicals released from notochord stimulate neurulation in the overlying ectoderm, first
forming the neural plate, then neural folds/groove, and ultimately neural tube
(The rest of organogenesis is another course -- embryology!)
Know what comes from ectoderm, mesoderm, endoderm -- Figure 28.13, page 1079
Additionally, you will need to know more about specializations of the mesoderm:
1. Somites, each with a sclerotome, myotome and dermatome (know what each one does)
2. Intermediate mesoderm (in abdominal region only) -- leads to gonads, kidneys
3. Lateral mesoderm: two sections
a. Somatic (dermis, parietal serosae, connective tissues of limbs)
b. Splanchnic (circulatory system, visceral serosae, smooth muscle/C.T. in walls of tubular
II. Fetal Stage: from completion of organogensis to birth (weeks 9 through term)
One of last events is maturation of the lung=s type II (surfactant-secreting) cells in 7th month
Effects of Pregnancy on Mother
Anatomical Changes: increased vascularization of reprod. organs, including vagina; incredible
enlargement of uterus; loosening/widening of pelvis (relaxin)
Metabolic Changes: Dietary requirements -- balanced nutrition, with around 300 extra calories a day
Know effects of human placental lactogen [hPL] (duh!) and human chorionic thyrotropin [hCT]
(hopefully also a "duh!")
Physiological Changes: to GI, urinary, respiratory, cardiovascular systems
Parturition -- Birth
Labor: placental estrogen production has increased during fetal stage; this stimulates formation of
oxytocin receptors on myometrial cells, and antagonizes progesterone
Fetus begins producing oxytocin causing placenta to release prostaglandins -- both oxytocin and
prostaglandins stimulate myometrial contraction, which in turn stimulates maternal release of
oxytocin from the hypothalamus/post. pit. (a positive feedback loop).
Adjustments of neonate to extrauterine life -- first breath, closing of circulatory shunts, temp. reg.
Lactation -- prolactin stimulates milk production (but colostrum first); actual nursing stimulates release
of oxytocin, which not only stimulates milk ejection (let-down) but also shrinking of uterus. Breast
milk is nutritive, protective and laxative, important for infant to release meconium. Continued nursing
has a distinctive (though not complete!) inhibition of GnRH release, and so is a natural birth control to