Brain-Testicular AxisBrain-Testicular Axis

Hormonal regulation of spermatogenesis and Hormonal regulation of spermatogenesis and testicular androgen production involving the testicular androgen production involving the hypothalamus, anterior pituitary gland, and the hypothalamus, anterior pituitary gland, and the testestestes

Brain-Testicular AxisBrain-Testicular Axis

Testicular regulation involves three sets of Testicular regulation involves three sets of hormones:hormones: GnRH, which indirectly stimulates the testes GnRH, which indirectly stimulates the testes

through: through: Follicle stimulating hormone (FSH)Follicle stimulating hormone (FSH) Luteinizing hormone (LH)Luteinizing hormone (LH)

Gonadotropins, which directly stimulate the testesGonadotropins, which directly stimulate the testes Testicular hormones, which exert negative Testicular hormones, which exert negative

feedback controlsfeedback controls

Hormonal Regulation of Hormonal Regulation of Testicular FunctionTesticular Function

The hypothalamus releases gonadotropin-The hypothalamus releases gonadotropin-releasing hormone (GnRH) releasing hormone (GnRH)

GnRH stimulates the anterior pituitary to GnRH stimulates the anterior pituitary to secrete FSH and LHsecrete FSH and LH FSH causes sustentacular cells to release androgen-FSH causes sustentacular cells to release androgen-

binding protein (ABP)binding protein (ABP) LH stimulates interstitial cells to release LH stimulates interstitial cells to release

testosteronetestosterone ABP binding of testosterone enhances ABP binding of testosterone enhances

spermatogenesisspermatogenesis

Hormonal Regulation Hormonal Regulation of Testicular Functionof Testicular Function

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

testosteronetestosterone Increased inhibinIncreased inhibin

Figure 27.10

Mechanism and Effects of Mechanism and Effects of Testosterone ActivityTestosterone Activity

Testosterone is synthesized from cholesterolTestosterone is synthesized from cholesterol It must be transformed to exert its effects on It must be transformed to exert its effects on

some target cellssome target cells Prostate – it is converted into dihydrotestosterone Prostate – it is converted into dihydrotestosterone

(DHT) before it can bind within the nucleus(DHT) before it can bind within the nucleus Neurons – it is converted into estrogen to bring Neurons – it is converted into estrogen to bring

about stimulatory effectsabout stimulatory effects Testosterone targets all accessory organs and Testosterone targets all accessory organs and

its deficiency causes these organs to atrophyits deficiency causes these organs to atrophy

Male Secondary Sex Male Secondary Sex CharacteristicsCharacteristics

Male hormones make their appearance at Male hormones make their appearance at puberty and induce changes in puberty and induce changes in nonreproductive organs, includingnonreproductive organs, including Appearance of pubic, axillary, and facial hairAppearance of pubic, axillary, and facial hair Enhanced growth of the chest and deepening of the Enhanced growth of the chest and deepening of the

voicevoice Skin thickens and becomes oilySkin thickens and becomes oily Bones grow and increase in densityBones grow and increase in density Skeletal muscles increase in size and massSkeletal muscles increase in size and mass

Male Secondary Sex Male Secondary Sex CharacteristicsCharacteristics

Testosterone is the basis of libido in both Testosterone is the basis of libido in both males and femalesmales and females

Female Reproductive AnatomyFemale Reproductive Anatomy

Ovaries are the primary female reproductive Ovaries are the primary female reproductive organsorgans Make female gametes (ova)Make female gametes (ova) Secrete female sex hormones (estrogen and Secrete female sex hormones (estrogen and

progesterone)progesterone) Accessory ducts include uterine tubes, uterus, Accessory ducts include uterine tubes, uterus,

and vaginaand vagina Internal genitalia – ovaries and the internal Internal genitalia – ovaries and the internal

ductsducts External genitalia – external sex organsExternal genitalia – external sex organs

The OvariesThe Ovaries

Paired organs on each side of the uterus held Paired organs on each side of the uterus held in place by several ligamentsin place by several ligaments Ovarian – anchors the ovary medially to the uterusOvarian – anchors the ovary medially to the uterus Suspensory – anchors the ovary laterally to the Suspensory – anchors the ovary laterally to the

pelvic wallpelvic wall Mesovarium – suspends the ovary in between Mesovarium – suspends the ovary in between

Broad ligament – contains the suspensory Broad ligament – contains the suspensory ligament and the mesovariumligament and the mesovarium

OvariesOvaries

Blood supply – ovarian arteries and the Blood supply – ovarian arteries and the ovarian branch of the uterine arteryovarian branch of the uterine artery

They are surrounded by a fibrous tunica They are surrounded by a fibrous tunica albuginea, which is covered by a layer of albuginea, which is covered by a layer of epithelial cells called the germinal epitheliumepithelial cells called the germinal epithelium

Embedded in the ovary cortex are ovarian Embedded in the ovary cortex are ovarian folliclesfollicles

OvariesOvaries

Each follicle consists of an immature egg Each follicle consists of an immature egg called an oocytecalled an oocyte

Cells around the oocyte are called:Cells around the oocyte are called: Follicle cells (one cell layer thick) Follicle cells (one cell layer thick) Granulosa cells (when more than one layer is Granulosa cells (when more than one layer is

present)present)

OvariesOvaries

Primordial follicle – one layer of squamouslike Primordial follicle – one layer of squamouslike follicle cells surrounds the oocytefollicle cells surrounds the oocyte

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

Secondary follicle – has a fluid-filled space Secondary follicle – has a fluid-filled space between granulosa cells that coalesces to form between granulosa cells that coalesces to form a central antruma central antrum

OvariesOvaries

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

Ovulation – ejection of the oocyte from the Ovulation – ejection of the oocyte from the ripening follicleripening follicle

Corpus luteum – ruptured follicle after Corpus luteum – ruptured follicle after ovulationovulation

OvariesOvaries

Figure 27.12

Uterine Tubes (Fallopian Tubes) Uterine Tubes (Fallopian Tubes) and Oviductsand Oviducts

Receive the ovulated oocyte and provide a site Receive the ovulated oocyte and provide a site for fertilizationfor fertilization

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

Expand distally around the ovary forming the Expand distally around the ovary forming the ampullaampulla

The ampulla ends in the funnel-shaped, The ampulla ends in the funnel-shaped, ciliated infundibulum containing fingerlike ciliated infundibulum containing fingerlike projections called fimbriaeprojections called fimbriae

Uterine TubesUterine Tubes

The uterine tubes have no contact with the The uterine tubes have no contact with the ovaries and the ovulated oocyte is cast into the ovaries and the ovulated oocyte is cast into the peritoneal cavityperitoneal cavity

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

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

Uterine TubesUterine Tubes

Nonciliated cells keep the oocyte and the Nonciliated cells keep the oocyte and the sperm nourished and moistsperm nourished and moist

Mesosalpinx – visceral peritoneum that Mesosalpinx – visceral peritoneum that supports the uterine tubessupports the uterine tubes

UterusUterus

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

Body – major portion of the uterusBody – major portion of the uterus Fundus – rounded region superior to the Fundus – rounded region superior to the

entrance of the uterine tubesentrance of the uterine tubes Isthmus – narrowed region between the body Isthmus – narrowed region between the body

and cervixand cervix

UterusUterus

Cervix – narrow neck which projects into the Cervix – narrow neck which projects into the vagina inferiorlyvagina inferiorly

Cervical canal – cavity of the cervix that Cervical canal – cavity of the cervix that communicates with:communicates with: The vagina via the external osThe vagina via the external os The uterine body via the internal osThe uterine body via the internal os

Cervical glands secrete mucus that covers the Cervical glands secrete mucus that covers the external os and blocks sperm entry except external os and blocks sperm entry except during midcycleduring midcycle

Supports of the UterusSupports of the Uterus

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

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

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

Round ligaments – bind the anterior wall to the Round ligaments – bind the anterior wall to the labia majoralabia majora

Peritoneal PouchesPeritoneal Pouches

Several culs-de-sac of peritoneum exist around Several culs-de-sac of peritoneum exist around the uterusthe uterus Vesicouterine pouch – lies between the bladder Vesicouterine pouch – lies between the bladder

and the uterusand the uterus Rectouterine pouch – lies between the rectum and Rectouterine pouch – lies between the rectum and

the uterusthe uterus

Uterine WallUterine Wall

Composed of three layersComposed of three layers Perimetrium – outermost serous layer; the visceral Perimetrium – outermost serous layer; the visceral

peritoneumperitoneum Myometrium – middle layer; interlacing layers of Myometrium – middle layer; interlacing layers of

smooth muscle smooth muscle Endometrium – mucosal lining of the uterine Endometrium – mucosal lining of the uterine

cavitycavity

EndometriumEndometrium Has numerous uterine glands that change in Has numerous uterine glands that change in

length as the endometrial thickness changeslength as the endometrial thickness changes Stratum functionalis:Stratum functionalis:

Undergoes cyclic changes in response to ovarian Undergoes cyclic changes in response to ovarian hormoneshormones

Is shed during menstruationIs shed during menstruation Stratum basalis:Stratum basalis:

Forms a new functionalis after menstruation endsForms a new functionalis after menstruation ends Does not respond to ovarian hormonesDoes not respond to ovarian hormones

Uterine Vascular SupplyUterine Vascular Supply

Uterine arteries – arise from the internal iliacs, Uterine arteries – arise from the internal iliacs, ascend the sides of the uterus and send branches ascend the sides of the uterus and send branches into the uterine wallinto the uterine wall

Arcuate arteries – branches of the uterine Arcuate arteries – branches of the uterine arteries in the myometrium that give rise to arteries in the myometrium that give rise to radial branchesradial branches

Radial branches – descend into the Radial branches – descend into the endometrium and give off:endometrium and give off: Spiral arteries to the stratum functionalisSpiral arteries to the stratum functionalis Straight arteries to the stratum basalisStraight arteries to the stratum basalis

Uterine Vascular SupplyUterine Vascular Supply

Degeneration and regeneration of spiral Degeneration and regeneration of spiral arteries causes the functionalis to shed during arteries causes the functionalis to shed during menstruationmenstruation

Veins of the endometrium are thin-walled with Veins of the endometrium are thin-walled with occasional sinusoidal enlargementsoccasional sinusoidal enlargements

VaginaVagina

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

The urethra is embedded in the anterior wallThe urethra is embedded in the anterior wall Provides a passageway for birth, menstrual Provides a passageway for birth, menstrual

flow, and is the organ of copulationflow, and is the organ of copulation

VaginaVagina

Wall consists of three coats: fibroelastic Wall consists of three coats: fibroelastic adventitia, smooth muscle muscularis, and a adventitia, smooth muscle muscularis, and a stratified squamous mucosa stratified squamous mucosa

Mucosa near the vaginal orifice forms an Mucosa near the vaginal orifice forms an incomplete partition called the hymenincomplete partition called the hymen

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

External Genitalia: Vulva External Genitalia: Vulva (Pudendum)(Pudendum)

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

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

Labia majora – elongated, hair-covered, fatty skin Labia majora – elongated, hair-covered, fatty skin folds homologous to the male scrotumfolds homologous to the male scrotum

Labia minora – hair-free skin folds lying within Labia minora – hair-free skin folds lying within the labia majora; homologous to the ventral penisthe labia majora; homologous to the ventral penis

External Genitalia: Vulva External Genitalia: Vulva (Pudendum)(Pudendum)

Greater vestibular glandsGreater vestibular glands Pea-size glands flanking the vagina Pea-size glands flanking the vagina Homologous to the bulbourethral glandsHomologous to the bulbourethral glands Keep the vestibule moist and lubricatedKeep the vestibule moist and lubricated

External Genitalia: Vulva External Genitalia: Vulva (Pudendum)(Pudendum)

Clitoris (homologous to the penis)Clitoris (homologous to the penis) Erectile tissue hooded by the prepuceErectile tissue hooded by the prepuce The exposed portion is called the glansThe exposed portion is called the glans

PerineumPerineum Diamond-shaped region between the pubic arch Diamond-shaped region between the pubic arch

and coccyx and coccyx Bordered by the ischial tuberosities laterallyBordered by the ischial tuberosities laterally

Mammary GlandsMammary Glands

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

Areola – pigmented skin surrounding the nippleAreola – pigmented skin surrounding the nipple Suspensory ligaments attach the breast to Suspensory ligaments attach the breast to

underlying muscle fasciaunderlying muscle fascia Lobes contain glandular alveoli that produce Lobes contain glandular alveoli that produce

milk in lactating womenmilk in lactating women Compound alveolar glands pass milk to Compound alveolar glands pass milk to

lactiferous ducts, which open to the outsidelactiferous ducts, which open to the outside

Breast CancerBreast Cancer Usually arises from the epithelial cells of the ductsUsually arises from the epithelial cells of the ducts Risk factors include:Risk factors include:

Early onset of menses or late menopauseEarly onset of menses or late menopause No pregnancies or the first pregnancy late in lifeNo pregnancies or the first pregnancy late in life Previous history of breast cancer or family history of breast Previous history of breast cancer or family history of breast

cancercancer Hereditary factors including mutations to the genes BRCA1 Hereditary factors including mutations to the genes BRCA1

and BRCA2and BRCA2 70% of women with breast cancer have no known risk 70% of women with breast cancer have no known risk

factorsfactors

Breast Cancer: Detection and Breast Cancer: Detection and TreatmentTreatment

Early detection is by self-examination and Early detection is by self-examination and mammographymammography

Treatment depends upon the characteristics of Treatment depends upon the characteristics of the lesionthe lesion

Radiation, chemotherapy, and surgery Radiation, chemotherapy, and surgery followed by irradiation and chemotherapyfollowed by irradiation and chemotherapy

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

OogenesisOogenesis

Production of female sex cells by meiosisProduction of female sex cells by meiosis In the fetal period, oogonia (2In the fetal period, oogonia (2nn ovarian stem ovarian stem

cells) multiply by mitosis and store nutrientscells) multiply by mitosis and store nutrients Primordial follicles appear as oogonia are Primordial follicles appear as oogonia are

transformed into primary oocytestransformed into primary oocytes Primary oocytes begin meiosis but stall in Primary oocytes begin meiosis but stall in

prophase Iprophase I

Oogenesis: PubertyOogenesis: Puberty At puberty, one activated primary oocyte At puberty, one activated primary oocyte

produces two haploid cells produces two haploid cells The first polar bodyThe first polar body The secondary oocyteThe secondary oocyte

The secondary oocyte arrests in metaphase II The secondary oocyte arrests in metaphase II and is ovulatedand is ovulated

If penetrated by sperm the second oocyte If penetrated by sperm the second oocyte completes meiosis II, yielding:completes meiosis II, yielding: One large ovum (the functional gamete)One large ovum (the functional gamete) A tiny second polar bodyA tiny second polar body

Figure 27.19

Ovarian CycleOvarian Cycle

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

Follicular phase – period of follicle growth Follicular phase – period of follicle growth (days 1–14)(days 1–14)

Luteal phase – period of corpus luteum Luteal phase – period of corpus luteum activity (days 14–28)activity (days 14–28)

Ovulation occurs midcycleOvulation occurs midcycle

Follicular PhaseFollicular Phase

The primordial follicle, directed by the oocyte, The primordial follicle, directed by the oocyte, becomes a primary folliclebecomes a primary follicle

Primary follicle becomes a secondary follicle Primary follicle becomes a secondary follicle The theca folliculi and granulosa cells cooperate to The theca folliculi and granulosa cells cooperate to

produce estrogensproduce estrogens The zona pellucida forms around the oocyteThe zona pellucida forms around the oocyte The antrum is formedThe antrum is formed

Follicular PhaseFollicular Phase

The secondary follicle becomes a vesicular The secondary follicle becomes a vesicular folliclefollicle The antrum expands and isolates the oocyte and The antrum expands and isolates the oocyte and

the corona radiatathe corona radiata The full size follicle (vesicular follicle) bulges The full size follicle (vesicular follicle) bulges

from the external surface of the ovaryfrom the external surface of the ovary The primary oocyte completes meiosis I, and the The primary oocyte completes meiosis I, and the

stage is set for ovulationstage is set for ovulation

Ovarian CycleOvarian Cycle

Figure 27.20

OvulationOvulation

Ovulation occurs when the ovary wall ruptures Ovulation occurs when the ovary wall ruptures and expels the secondary oocyteand expels the secondary oocyte

Mittelschmerz – a twinge of pain sometimes Mittelschmerz – a twinge of pain sometimes felt at ovulationfelt at ovulation

1-2% of ovulations release more than one 1-2% of ovulations release more than one secondary oocyte, which if fertilized, results in secondary oocyte, which if fertilized, results in fraternal twins fraternal twins

Luteal PhaseLuteal Phase After ovulation, the ruptured follicle collapses, After ovulation, the ruptured follicle collapses,

granulosa cells enlarge, and along with internal granulosa cells enlarge, and along with internal thecal cells, form the corpus luteumthecal cells, form the corpus luteum

The corpus luteum secretes progesterone and The corpus luteum secretes progesterone and estrogenestrogen

If pregnancy does not occur, the corpus luteum If pregnancy does not occur, the corpus luteum degenerates in 10 days, leaving a scar (corpus degenerates in 10 days, leaving a scar (corpus albicans)albicans)

If pregnancy does occur, the corpus luteum If pregnancy does occur, the corpus luteum produces hormones until the placenta takes produces hormones until the placenta takes over that role (at about 3 months)over that role (at about 3 months)

Establishing the Ovarian CycleEstablishing the Ovarian Cycle

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

As puberty nears, GnRH is released; FSH and As puberty nears, GnRH is released; FSH and LH are released by the pituitary, which act on LH are released by the pituitary, which act on the ovariesthe ovaries

These events continue until an adult cyclic These events continue until an adult cyclic pattern is achieved and menarche occurspattern is achieved and menarche occurs