Reproductive Systems

Gonads

site of gamete formation and steroid hormone production and release

Male gonads

testes

Female gonads

ovaries

Adrenogenital syndrome

genitals of baby girl (with this syndrome) are masculinized by prenatal hypersecretion of adrenal androgens

Adrogen sensitivity syndrome

individuals are genetically male (XY)

external genitalia and secondary sex characteristics are feminine but no ovaries, uterus, or vagina

XXX Syndrome: Klinefelter Syndrome

individuals are genetically male

* low testosterone, decreased muscle mass and body hair, breast enlargement
* increased incidence of infertility

HPG axis

hypothalamus → GnRH → anterior pituitary → GnRH receptors on gonadotropes → FSH and LH → gonads

GnRH

* Gonadotropic releasing hormone
* from hypothalamus
* acts through receptors on gonadotropes ( cells in anterior pituitary that make LH and FSH)

LH and FSH

* leutinizing and follicle stimulating hormone
* from gonadotropes in adendohypophysis
* glycoproteins
* binds receptors in gonads

FSH in Males

* stimulate sertoli cells
* promote proliferation and differentiation of sperm
* produce androgen-binding proteins
* bind androgen hormones to maintain high stable reservoir of androgens (required for sperm maturation) in the tubular fluid
* produce Inhibin = glycoprotein hormone that has direct inhibitory effects on adenohypophysis
* inhibits FSH but not LH release
* may have small effect on GnRH release from hypothalamus

FSH in Females

* stimulates granulosa cell proliferation that allow first stages of maturation of follicle to occur
* inhibin is released from the corpus luteum = temporary endocrine organ formed following ovulation
* decreases FSH levels which inhibits development of new follicle until next cycle

LH

stimulates steroid secretions from Leydig and Theca cells

LH in Males

* Leydig cells = secretes series of androgens
* testosterone = most prevalent steroid secreted
* binds to nuclear receptor in target tissue → complex alters gene transcription

LH in Females

* theca cells, granulosa cells, and corpus luteum secrete a series of estrogens
* estradiol = most prevalent type of estrogen
* secreted by follicle, corpus luteum, and placenta
* promotes proliferation and growth of specific sex-related cells of body
* Progesterone:
* secreted by corpus luteum and placenta with small amount of follicle
* effects almost entirely in preparation for pregnancy
* uterus: promotes secretory changes in endometrium
* breasts: promotes development of lobules and increased number of acinar cells

Testes hormones

FH = sperm production (exocrine, into ducts)

LSH = testosterone (- feedback) (endocrine, secreted into blood)

Ovary hormones

FH = follicle development, estrogen (- feedback)

LSH = ovulation

Male-specific function

manufacture sperm and deliver it to female’s reproductive tract

Testes

* surrounded by tunica albuginea = white fibrous CT → plunges into testes and divides into lobules → contain seminiferous tubules → tubules merge into rete testes and recieve sperm and dump into duct system

Seminiferous tubules

site of sperm production

Epididymis

* coiled tube that cups superior part of testes and travels down posterolateral part
* temporary storage site for immature sperm
* mature sperm travel down this (20 days)

Ductus (vas) deferens

* F(X): propel sperm from epididymis into urethra during ejaculation
* runs up form epididymis through inguinal canal to pelvic cavity and arches over bladder, then loops medially over uterus and descends along posterior bladder walls
* expands into ampulla of ducts and empties into ejaculatory duct
* cut/carterized during vasectomy

Male Accessory glands

= make seminal fluid that the sperm swim in

* seminal vesicle
* prostate
* bulbourethral (Cowper’s) gland

Seminal Vesicles

* produce 60% seminal fluid
* thick, yellow secretion rich in sugar, vit. C, prostaglandins (nourish and activate sperm)
* converse with ductus deferens to make ejaculatory duct

Prostate gland

* produce milky fluid that activates sperm
* felt through rectum during physical exam

Bulbourethral gland

* produce thick, clear mucus into penile urethra
* 1st fluid to travel down urethra when XY is sexually excited → clearing out acidic urine and lubricating

Raphe (balls)

* contain testes
* hangs loose for temperature control

Scrotal septum

draw testes closer or further from body for temp regulation

Ovary

* produce female gametes (ova)
* secrete female sex hormones (progesterone and estrogen)
* anchored by ligaments

Suspensory ligament

maintains lateral placement of ovary

Ovarian Ligament

holds ovary in place medially

internal ovary structure

from inside to outside:

* medulla = blood vessels and nerves
* cortex = ovarian follicles
* tunica albuginea

Female Duct System

provides passageway out for ovulated egg and possible entry for sperm

* uterine tubes
* uterus
* uterine walls

male duct system

transports sperm from body

Uterine tubes

* non-ciliated cells nourish the oocyte and any sperm that has gained admittance to this region
* peristalsis and ciliary action move the oocyte along its path toward the ampulla and isthmus of the oviduct
* fimbriae, finger-like extension, create currents to move oocyte into uterine tube, catch ovulated oocyte as it leaves ovary

transport of oocyte from ovary to uterus

ovary → fimbriae → infundibulum → ampulla → isthmus → interstitium → uterus

Uterus

* harbor fetus
* provide nutrition to fetus
* expel fetus
* anchored by broad and round ligaments

Wall of uterus (from inside to outside)

* endometrium = mucosal lining
* myometrium = smooth muscle layer
* perimetrium = serous layer; connective tissue

Stratum Functionalis of the endometrium

changes with hormone levels, shed during menstruation

Stratum Basalis of endometrium

* forms new stratum functionalis
* unresponsive to hormones

Endometriosis

edometrial tissue grows in the pelvic cavity on the perimetrium or on the ovary, sometimes results in infertility

Fibroids

noncancerous growth of uterus appear

Symptoms: heavy or prolonged menstrual bleeding, pelvic pain, frequent urination, constipation, and difficulty emptying one’s bladder

Vagina

* discharge menstrual fluid
* copulation
* route of exit for developed fetus
* hymen = folding of vaginal mucosa at vaginal orifice
* childhood = simple cuboidal
* after puberty = stratified squamous, protect against abrasion
* glycogen → lactic acid = protection
* low pH = 3.5-4
* dendritic cells (WBCs) = protection

the vulva

* mons pubis
* clitoris
* vestibule
* labia majora and minora
* urethral orifice
* vaginal orifice

mons pubis

hair, front and top

labium majora

homologous to scrotum in male, is the outer layer folds that often are covered with sparse hairs

labia minora

homologous to ventral penis in male, is the inner folds

vaginal orifice

access to vagina

prepuce

hoods

clitoris

erectile tissue

urethral orifice

urine from urethra, no reproductive function

vestibule

doorway to vaginal orifice and deeper structures

greater vestibule gland

homologous to the bulbourethral glands in males, secrete mucus for lubrication during intercourse

Areola

contains dermal capillaries and nerves, which make it dark and sensitive

areolar glands

small bumps on surface of breast that protect nipple from chapping/cracking during nursing

breasts in pregnancy

increase melatonin production, makes nipple darker and more visible to newborn infant so it can latch onto breast more easily

What are the ovarian events?

1. follicular phase
2. ovulation
3. luteal phase

What are the uterine events?

1. menstruation
2. proliferative phase
3. secretory phase

What does the corpus luteum produce/make?

progesterone

What does the developing follicle produce/make?

estrogen

Follicular phase steps

* 1-13 days


1. hypothalamus secretes GnRH
2. GnRH causes anterior pituitary to release FSH and LH
3. FSH develops follicle
4. 1 degree follicle → graffin follicle (mature)
5. graffin follicle secrete estrogen to high levels
6. estrogen secretion cause a positive feedback effect on GnRH, FSH, and LH
7. low estrogen levels cause negative feedback effect on GnRH, LH, and FSH

Ovulation steps

1. on day 13, surge of LH, increase estrogen → causes ovulation
2. oocytes either ovulates or turns into corpus luteum

Signs of ovulation

* cervical mucus really thin and stretchy
* helps sperm get through to egg
* a rise in body temp (0.4-0.5), very small change
* Mittelschmerz = “middle pain”

Luteal phase

1. leftover graffin follicles become corpus luteum = produces progesterone (and estrogen and inhibin)
2. corpus luteum needs LH in order to survive
3. as LH levels fall due to hormones, the Corpus luteum degenerates into corpus albicans
4. hormones inhibit GnRH, LH, and FSH secretion, negative feedback effect on hypothalamus and anterior pituitary

Menstruation

* bleeding
* stratum functionalis is slaughed off

Proliferative phase

* after menstruation till ovulation
* cells of endometrial glands grow and develop due to estrogen from Graffin follicle

Secretory phase

* ovulation to next menstruation
* causes endometrial glands to secrete substances that support implantation (fertilization)

Male sexual response

1. Excitment
2. orgasm - emission stage
3. orgasm - expulsion stage
4. resolution

Male: Excitement

visual, mental, physical stimulation = PNS activation

* deep artery of penis dilates
* corpus cavernosum engorges urethra open
* bulbourethral gland secretes bulbourethral fluid (precum)

Male: orgasm - emission stage

* SNS fibers from lumbar region activate ductus deferens
* moves sperm (via peristalsis) into ampulla and then into prostatic urethra
* prostate and seminal vesicles secrete fluid (joins sperm to make semen)
* semen in urethra

Male: orgasm - expulsion stage

* SNS activation
* more prostatic and seminal fluids
* constriction of internal urethral sphincter (no peeing)
* Somatic NS activation
* bulbocavernosum muscle contracts and compresses bulb and root of penis to ejaculate sperm

Male: Resolution

* artery of the penis (internal pudential artery) constricts therefore decrease in blood flow
* trabecular muscle contracts = squeezes blood from erectile tissue
* penis becomes flacid

Female sexual response

1. Excitement
2. plateau
3. orgasm
4. resolution

Female: Excitement

* visual, mental, physical stimulation = PNS Activation
* increases blood flow to reproductive organs
* vaginal transudate (ultra filtrate of plasma across vaginal vessels) moistens vagina and vestibule

Female: Plateau

* uterus is tented (erected) and cervix is withdrawn from vagina
* orgasmic platform of vagina constricts penis
* clitoris is engorged

Female: Orgasm

* under SNS control
* orgasmic platform constricts rhythmically
* uterus exhibits peristaltic contractions
* sphincters constrict

Female: resolution

* uterus returns to original position
* orgasmic platform relaxes
* inner end of vagina constricts and returns to original dimensions

Male erectile dysfunction

impotence = inability to achieve/develop or maintain erection

Folliculogenesis

development of egg and follicle

Oocyenesis

oocyte production and development

Development of oocyte

primordial follicle → primary follicles → secondary follicles → mature follicle → oocyte → ovulated oocyte → corpus luteum → corpus albicans

diploid

2n

haploid

n

Spermatogenesis

formation of sperm → begins at puberty through life, make millions of sperm each day

Semen

milky white, sticky mix of sperm and accessory gland secretions

* antibiotic chemicals (destroy bacteria)
* relaxin (helps open/relax female duct system)
* motility enzymes ( increase motility)
* immune inhibitors (sperm are not attacked or destroyed)
* fructose ( rely on for fuel due to limited nutrients)
* alkaline

maturation of sperm

1. acrosomal vesicle, lysosome sac penetrate oocyte, falgellum (propel sperm)
2. growth of acrosome and flagellum
3. excess cytoplasm, compact DNA
4. compact DNA, mitochondria, no excess cytoplasm

process of spermatogenesis

Type A daughter cell (2n) → mitosis → Type B daughter cell (2n) → meiosis I → primary spermatocyte → secondary spermatocytes → meiosis II → early/late spermatids → spermatozoa

Where does maturation of sperm take place in the testes?

seminiferous tubules

What are the germ cells in male and females?

males = sperm

female = ovum

support cells

= cells closest in proximity to germ cells

* helps maintain germ cells by providing nutrients, hormones, and enzymes necessary for differentiation

What are the support cells of males and females?

male = sertoli cells

female = granulosa cells

Interstitial cells

* found in connective tissue
* produce steroid hormones
* LH acts on these hormones

What are the interstitial cells of males and females?

male = leydig cells

female = theca cells

Leydig cells

located between seminiferous tubules

theca cells

located around perimeter of follicles (structure containing developing ovum)

Why are there low levels of testosterone and estrogen in childhood?

low levels of GnRH released from hypothalamus

Puberty

* increase GnRH just prior to puberty
* males = increase is constant
* females = increase is pulsatile
* in females, amount of FSH/LH varies and causes large shifts in concentration of 2 major ovarian hormones: estradiol and progesterone
* results in menstrual cycle and development of primary and secondary sex organs

Growth and development of primary sex organs: Males

testis, scrotum, penis

Growth and development of primary sex organs: females

ovaries, fallopian tubes, uterus, vagina

Growth and development of secondary sex characteristics: Males

* body hair, deepened voice due to enlargement of laryngeal cartilage, thickening of mucosa (vocal cords), and thickening of skin
* increase anabolic effect → increase protein synthesis, increase skeletal muscle mass
* increase bone development: increase length and thickness

Growth and development of secondary sex characteristics: Females

* body hair, deepened voice due to enlargement of laryngeal cartilage, thickening of mucosa (vocal cords), thickening of skin
* increase anabolic effect → increase protein synthesis but weaker than testosterone so less skeletal muscle and bone mass then men
* increase bone development, increase height
* increase subcutaneous fat deposition: development of rounded buttocks and breasts