• Primary sex organs (gonads) – testes in males, ovaries in females

• Gonads produce sex cells called gametes and secrete sex hormones

• Male gametes - Sperm • Female gametes - Ova (eggs)

• Sex hormones – androgens (males), and estrogens and progesterone (females)

• Accessory reproductive organs – ducts, glands, and external genitalia

• The male gonads (testes) produce sperm and lie within the scrotum

• Sperm are delivered to the exterior through a system of ducts: 1. Epididymis2. Ductus deferens3. Ejaculatory duct 4. Urethra

Ductusdeferens

Ejaculatoryduct

UrethraEpididymis

• Accessory sex glands:– Empty their secretions

into the ducts during ejaculation

1. Seminal vesicles 2. Prostate gland3. Bulbourethral glands

• External genitalia– Penis– Scrotum

Seminalvesicles

Prostategland

Bulbourethralgland

• Sac of skin hangs outside the abdominopelvic cavity between legs and at the root of the penis

• Contains paired testes separated by a midline septum

• Its external positioning keeps the testes 3C lower than core body temperature (needed for sperm production)

• Intrascrotal temperature is kept constant by two sets of muscles:1. Cremaster – bands of

skeletal muscle that elevate the testes

2. Dartos – smooth muscle that wrinkles scrotal skin

CremasterMuscle

Dartos Muscle

• Plum size – 4-5 cm long• Serve as both

– Exocrine gland: sperm cells are the secretion

– Endocrine: testosterone• Each testis is surrounded by

two tunics: 1. The tunica vaginalis,

derived from peritoneum2. The tunica albuginea, the

fibrous capsule of the testis

TunicaVaginalis

TunicaAlbuginea

Seminiferoustubules

Tubulusrectus

Seminiferoustubules

ReteTestes

Epididymis

• Extension of T. albuginea forms the septa

• Septa divide the testis into 250-300 lobules, each contains 1-4 seminiferous tubules• Surrounding the seminiferous

tubules are interstitial cells that produce androgens

• Seminiferous tubules:– Produce the sperm– Converge to form the tubulus

rectus • Tubulus rectus conveys sperm to

the rete testis• From rete testis sperm enter the

epididymis via efferent ductules

• Copulatory organ - deliver sperm into the female reproductive tract

• Consists of an attached root and a free shaft that ends in the glans penis

• loose fold of skin covers the glans penis - Prepuce, or foreskin

• Circumcision – surgical removal of the foreskin after birth

• Inner side of penis contains the urethra and three columns of erectile tissue

• Erection – erectile tissue fills with blood causing the penis to enlarge and become rigid

• Corpus cavernosa – two erectile columns forms the dorsal side of penis

• Corpus spongiosum – third column forms the ventral side of penis

• Surrounds the urethra and expands to form the glans and bulb of the penis

• Epididymis

• Ductus (vas) deferens

• Urethra

Duct System

• From seminiferous tubule sperm pass through tubulus rectus - rete testis - efferent ductules – epididymis

• Site of sperm cell maturation• Contains Head, body, tail• The duct of the epididymis has

stereocilia that:– Absorb fluid from the lumen of

epididymis– Pass nutrients to the sperm

• Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens

• Ductus deferens runs from the epididymis to ejaculatory duct into the pelvic cavity

• Terminal end expands to form the ampulla and then joins the duct of the seminal vesicle to form the ejaculatory duct

• Ejaculatory duct propels sperm from the epididymis to the urethra

• Vasectomy – cutting and ligating the ductus deferens, which is a nearly 100% effective form of birth control

• Conveys both urine and semen (at different times)

• Consists of three regions 1. Prostatic – portion surrounded

by the prostate

2. Membranous – lies in the urogenital diaphragm, from prostatic urethra to spongy urethra

3. Spongy, or penile – runs through the penis and opens to the outside at the external urethral orifice

Prostatic

Membranous

Spongy(Penile)

• Lie on the posterior wall of the bladder and secrete 60% of the volume of semen– Semen – viscous alkaline fluid

containing fructose, ascorbic acid, coagulating enzyme (vesiculase), and prostaglandins

• Join the ductus deferens to form the ejaculatory duct

• Sperm and seminal fluid mix in the ejaculatory duct and enter the prostatic urethra during ejaculation

SeminalVesicles (Glands)

60%

ProstateGland

30%

• Doughnut-shaped gland that encircles part of the urethra inferior to the bladder

• Its milky, slightly acid fluid, which contains citrate, enzymes, and prostate-specific antigen (PSA), accounts for one-third of the semen volume

• Plays a role in the activation of sperm

• Enters the prostatic urethra through several small ducts during ejaculation

BulbourethralGland

• Pea-sized glands inferior to the prostate

• Produce thick, clear mucus prior to ejaculation that neutralizes traces of acidic urine in the urethra

• Milky white, sticky mixture of sperm and accessory gland secretions

• Provides a transport medium and nutrients (fructose), protects and activates sperm, and facilitates their movement

• Prostaglandins in semen:– Decrease the viscosity of mucus in the cervix– Stimulate reverse peristalsis in the uterus– Facilitate the movement of sperm through the female

reproductive tract

• The hormone relaxin enhances sperm motility

• The relative alkalinity of semen neutralizes the acid environment found in the male urethra and female vagina

• Seminalplasmin – antibiotic chemical that destroys certain bacteria

• Clotting factors coagulate semen immediately after ejaculation, then fibrinolysin liquefies the sticky mass, enable the sperm to swim out

• Only 2-5 ml of semen are ejaculated, but it contains 50-130 million sperm/ml

• Phases of male sexual response are:• Erection• Ejaculation

• Erection:• Enlargement and stiffening of the penis

from engorgement of erectile tissue with blood

• During sexual arousal, a PNS reflex promotes the release of nitric oxide

• Nitric oxide causes erectile tissue to fill with blood

• Expansion of the erectile tissue:– Compresses their drainage veins– Retards blood outflow and maintains

engorgement

Parasympathetic

Artery

Vein

• The propulsion of semen from the male duct system

• At ejaculation, sympathetic nerves causes:

– Reproductive ducts and accessory organs to contract and empty their contents into urethra

– The bladder sphincter muscle to constrict, preventing the expulsion of urine

– Bulbospongiosus muscles of penis to undergo a rapid series of contractions and propel semen from the urethra

Sympathetic

spermsemen

• Production of sperm cells

• Begins at puberty and continues throughout life

• Occurs in the seminiferous tubules

• The sequence of events that produces sperm in the seminiferous tubules of the testes

• Each cell has two sets of chromosomes (one maternal, one paternal) and is said to be diploid (2n chromosomal number)

• Humans have 23 pairs of homologous chromosomes

• Gametes only have 23 chromosomes and are said to be haploid (n chromosomal number)

• Gamete formation is by meiosis, in which the number of chromosomes is halved (from 2n to n)

• Spermatogenic cells in seminiferous tubules give rise to sperm in a series of events– Mitosis of spermatogonia,

forming spermatocytes

– Meiosis forms spermatids from spermatocytes

– Spermiogenesis – spermatids form sperm

• Spermatogonia (stem cells) in outer edge of seminiferous tubules of testes undergo mitosis to produce more stem cells from birth until puberty

• Spermatogenesis begins at puberty

• Each mitotic division of spermatogonia results in type A or type B daughter cells

• Type A cells remain at the basement membrane and maintain the stem line

• Type B cells move toward the lumen and become primary spermatocytes

• Primary spermatocytes undergo meiosis I, forming two haploid cells called secondary spermatocytes

• Secondary spermatocytes undergo meiosis II and forms 4 haploid cells – spermatids– Spermatids—23

chromosomes)

• Spermatids are small round cells seen close to the lumen of the tubule

• Spermatids are haploid, nonmotile• Spermiogenesis – spermatids lose excess cytoplasm and form a tail,

becoming sperm• Sperm have three major regions

– Head – contains DNA and has a helmetlike acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg

– Midpiece – contains mitochondria spiraled around the tail filaments– Tail – a typical flagellum produced by a centriole– Spermatogenesis takes 64 to 72 days

• Sustentacular (Sertoli, nurse) cells extend from the periphery to the lumen of the seminiferous tubule

• Nourish sperm cells and form a blood-testis barrier and produce hormones

• Tight junctions between Sustentacular Cells form a blood-testis barrier

• This prevents sperm antigens from escaping through the basal lamina into the blood – can activate immune system

• And divide seminiferous tubule into two compartments

– The basal compartment – contains spermatogonia and primary spermatocytes– Adluminal compartment – contains meiotically active cells and the tubule lumen

• Hormonal regulation of male reproductive system involves interaction between

1. Hypothalamus 2. Anterior pituitary

gland3. Testes

• The hypothalamus releases gonadotropin-releasing hormone (GnRH)

• GnRH stimulates the anterior pituitary to secrete FSH and LH– FSH prompts

spermatogenesis – LH stimulates interstitial

cells to release testosterone

• Feedback inhibition on the hypothalamus and pituitary results from:– Rising levels of testosterone

– Inhibits hypothalamus to release GnRH

– High sperm count releases Inhibin – Protein Hormone

– Inhibin reduces FSH secretion from ant. pituitary

• Male hormones (Testosterone) make their appearance at puberty

• Functions of testosterone– Stimulates reproductive organ

development to their adult size– Underlies sex drive– Causes secondary sex characteristics

• Deepening of voice• Increased hair growth ( beard and

mustache)• Enlargement of skeletal muscles• Thickening of bones

• Female reproductive organs consists of :

• Ovaries• Uterine tubes• Uterus• Vagina• External genital organs• Mammary glands• Ovaries are the primary

female reproductive organs– Make female gametes

(ova)– Secrete female sex

hormones (estrogen and progesterone)

• Paired organs on each side of the uterus held in place by several ligaments– Ovarian – anchors the

ovary medially to the uterus

– Suspensory – anchors the ovary laterally to the pelvic wall

– Mesovarium – suspends the ovary in between

• Broad ligament – contains the suspensory ligament and the mesovarium

• Visceral peritoneum made up of simple cuboidal epithelium covers the surface of ovary – Germinal epithelium

• Below germinal epithelium is a fibrous capsule – tunica albuginea• Cortex – Denser outer part of the ovary , Contains Ovarian follicles

with oocytes• Medulla: looser, inner part, Contains blood vessels, nerves,

lymphatic vessels• Stroma: connective tissue of the ovary

• Each ovarian follicle consists of an immature egg called an

oocyte• Cells around the oocyte are called:

– Follicle cells (one cell layer thick) – Granulosa cells (when more than one layer is present)

• Follicles at different stages of maturation are distinguished by their structure:

• Primordial follicle – one layer of squamous like follicle cells surrounds the oocyte

• Primary follicle – two or more layers of cuboidal granulosa cells enclose the oocyte

• A layer of clear material is deposited around primary oocyte – Zona pellucida

• Secondary follicle – has a fluid-filled space between granulosa cells called vesicles

• Theca – Capsule forms around the follicle

• Mature or Graafian follicle – secondary follicle at its most mature stage that bulges from the surface of the ovary

• Fluid filled vesicles fuse - Antrum• Oocytes surrounded by mass of

granulosa cells – Cummulus cells• Innermost cells – Corona Radiata

• Ovulation – ejection of the oocyte from the ripening follicle

• Corpus luteum – ruptured follicle after ovulation

• If Pregnancy occurs – Remains as Corpus Luteum of Pregnancy

• If no Pregnancy - degenerates

• Receive the ovulated oocyte and

provide a site for fertilization

• Empty into the superolateral region of the uterus via the isthmus

• Distal end expand around the ovary forming the ampulla

• Ampulla ends in infundibulum, funnel-shaped structure bearing ciliated fingerlike projections called fimbriae

• Uterine tubes have no contact with the ovaries and the ovulated oocyte is cast into the peritoneal cavity

• Beating cilia on the fimbriae create currents to carry the oocyte into the uterine tube

• The oocyte is carried toward the uterus by peristalsis and ciliary action

• Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder

• Body – major portion of the uterus

• Fundus – rounded region superior to the entrance of the uterine tubes

• Isthmus – narrowed region between the body and cervix

• Cervix – narrow outlet that narrow outlet that protrudes into the vaginaprotrudes into the vagina

• Cervical canal – cavity of the cervix that communicates with:– The vagina via the

external ostium– The uterine body via the

internal ostium• Cervical glands secrete

mucus that covers the external os and blocks sperm entry except during midcycle

• Mesometrium – portion of the broad ligament that supports the uterus laterally

• Lateral cervical ligaments – extend from the cervix and superior part of the vagina to the lateral walls of the pelvis

• Uterosacral ligaments – paired ligaments that secure the uterus to the sacrum

• Round ligaments – Extend from uterus to the external genitalia

• Composed of three layers– Perimetrium – outermost

serous layer; the visceral peritoneum

– Myometrium – middle layer; interlacing layers of smooth muscle

– Endometrium – mucosal lining of the uterine cavity

– shed during menstruation

• Thin-walled tube lying between the bladder and the rectum, extending from the cervix to the exterior of the body

• Provides a passageway for birth, menstrual flow, and is the organ of copulation

• Mucosa near the vaginal orifice (opening) forms an incomplete partition called the hymen

• Vaginal fornix– upper end of the vagina surrounding the cervix

• Lies external to the vagina and includes the mons pubis, labia, clitoris, and vestibular structures

• Mons pubis – round, fatty area overlying the pubic symphysis

• Labia majora – elongated, hair-covered, fatty skin folds

• Labia minora – hair-free skin folds lying within the labia majora

• Greater vestibular glands - Pea-size glands flanking the vagina - Keep the vestibule moist and lubricated

• Clitoris (homologous to the penis)– Erectile tissue – The exposed portion is called the glans

• Modified sweat glands consisting of 15-25 lobes that radiate around and open at the nipple – Lactiferous ducts

• Areola – pigmented skin surrounding the nipple

• Suspensory ligaments attach the breast to underlying muscle fascia

• Lobes contain glandular alveoli that produce milk in lactating women

• Glandular alveoli pass milk to lactiferous ducts, which open to the outside

• Usually arises from the epithelial cells of the smallest ducts

• Risk factors include:– Early onset of menses or late menopause– No pregnancies or the first pregnancy late in life– Previous history of breast cancer or family history of breast

cancer– Hereditary factors including mutations to the genes BRCA1

and BRCA2• 70% of women with breast cancer have no known risk

factors

• Early detection is by self-examination and mammography

• Treatment - Radiation, chemotherapy, and surgery followed by irradiation and chemotherapy

• Today, lumpectomy is the surgery used rather than radical mastectomy

• The total supply of eggs are present at birth• Ability to release eggs begins at puberty• Reproductive ability ends at menopause• Oocytes are matured in developing ovarian follicles

• Oogonia – female stem cells found in a developing fetus

– Oogonia undergo mitosis to produce daughter cells, primary oocytes

– Primary oocytes are surrounded by cells that form primary follicles in the ovary

– Oogonia no longer exist by the time of birth

– By birth, female has 7 million oocytes stored

• Primary oocytes are inactive until puberty

• Follicle stimulating hormone (FSH) causes some primary follicles to mature each month

– Meiosis starts inside maturing follicle

• Produces a secondary oocyte and the first polar body

– Meiosis is completed after ovulation only

– Ovulation occurs in response to Luteinizing hormone (LH)

• if sperm penetrates• ovum is produced• Two additional polar bodies are

produced• Once ovum is formed, the 23

chromosomes can be combined with those of the sperm to form the fertilized egg (zygote)

• If the secondary oocyte is not penetrated by a sperm, it dies and does not complete meiosis to form an ovum

• Monthly series of events associated with the maturation of an egg

• Two Phases:• Follicular phase – period of follicle growth

(days 1–14)• Luteal phase – period of corpus luteum activity

(days 14–28)• Ovulation occurs midcycle

• During childhood, ovaries grow and secrete small amounts of estrogens that inhibit the hypothalamic release of GnRH

• As puberty nears, hypothalamus is less sensitive to estrogen and release GnRH

• GnRH stimulates ant. Pituitary to release FSH and LH, prompt ovaries to secrete estrogen

• Day 1 – GnRH stimulates the release of FSH and LH

• FSH and LH stimulate follicle growth and maturation, and estrogen secretion

• FSH exerts effect on Granulosa cells

• LH effects thecal cells

• Rising estrogen levels:– Inhibit the release of FSH and

LH – Negative feedback

• Estrogen levels increase and high estrogen levels have a positive feedback effect on the pituitary, causing a sudden surge of LH

• Day 14 – LH triggers ovulation

• LH transforms the ruptured follicle into a corpus luteum, which produces inhibin, progesterone, and estrogen

• These hormones shut off FSH and LH release and declining LH ends luteal activity

• Days 26-28 – decline of the ovarian hormones

• Ends the blockade of FSH and LH, new cycle starts

• Series of cyclic changes that the uterine endometrium goes through each month in response to ovarian hormones in the blood

• Menstrual phase – Days 1–5– Functional layer of the endometrium is sloughed – Bleeding occurs for 3–5 days– By day 5, growing ovarian follicles are producing

more estrogen

• Proliferative stage – Days 6–14– Regeneration of functional layer of the

endometrium– Estrogen levels rise– Ovulation occurs in the ovary at the end of this

stage

• Secretory stage – Days 15–28– Levels of progesterone rise and increase the blood supply to the

endometrium– Endometrium increases in size and begin secreting nutrients into

the uterine cavity and sustain a developing embryo– If fertilization does occur

• Embryo produces a hormone that causes the corpus luteum to continue producing its hormones

– If fertilization does NOT occur• Corpus luteum degenerates as LH blood levels decline• Endometrial cells die• Sets the stage for menses again on day 28

• 40-50 years old. Menstrual periods become less regular, ovulation stops. Female climacteric (perimenopause)

• Cessation of menstrual cycles – menopause

• LH and FSH elevated, but the few remaining follicles become insensitive to LH and FSH

• Ovaries stop producing estrogen and progesterone

• Symptoms: hot flashes, irritability, night sweats, fatigue, anxiety, occasionally severe emotional disturbances.

• Estrogen levels rise during puberty

• Promote oogenesis and follicle growth in the ovary

• Effect on the female reproductive tract

– Uterine tubes, uterus, and vagina grow larger and become functional

– Uterine tubes and uterus exhibit enhanced motility

– Vaginal mucosa thickens and external genitalia mature

• Growth of the breasts

• Increased deposition of subcutaneous fat, especially in the hips and breasts

• Widening and lightening of the pelvis

• Growth of axillary and pubic hair

• In some, testes decrease in size

• Decrease in number of interstitial cells, thinning of walls of seminiferous tubules

• Decrease in rate of sperm cell production

• Changes in Prostate: decrease in blood flow, increase in thickness of epithelial lining, decrease in functional smooth muscle cells

• Menopause

• Uterus decreases 50% in size within 15 years after menopause

• Vaginal wall: thinner, less elastic, less lubrication. Increased incidence of vaginal infections

• Increased risk of breast, endometrial, cervical, and ovarian cancer