Reproduction Male

8/6/2019 Reproduction Male

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The Reproductive SystemThe Reproductive SystemMaleMale

Prof. Marie Vonne Olivar VenusProf. Marie Vonne Olivar Venus


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TheThe Reproductive SystemReproductive System

GonadsGonads:: organs that produceorgans that produce gametesgametes and hormonesand hormones

DuctsDucts::

receive and transport gametesreceive and transport gametes

Accessory glands:Accessory glands:

secrete fluids into ductssecrete fluids into ducts

Perineal structures:Perineal structures:

collectively known ascollectively known as external genitaliaexternal genitalia


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Male & Female ReproductiveMale & Female Reproductive

SystemsSystemsAre functionally differentAre functionally different

Female produces 1 gamete per month:Female produces 1 gamete per month:

retains and nurtures zygoteretains and nurtures zygote

Male disseminates large quantities of gametes:Male disseminates large quantities of gametes:

produces 1/2 billion sperm per dayproduces 1/2 billion sperm per day


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The Male Reproductive SystemThe Male Reproductive System

TestesTestes or male gonads:or male gonads: secrete male sex hormones (androgens)secrete male sex hormones (androgens)

produce male gametes (produce male gametes (spermatozoaspermatozoa or sperm)or sperm)

EmissionEmission:: mature spermatozoa move along duct systemmature spermatozoa move along duct system

SemenSemen:: sperm mixed with accessory gland secretionssperm mixed with accessory gland secretions

EjaculationEjaculation:: semen expelled from bodysemen expelled from body


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What are the components of the maleWhat are the components of the malereproductive system?reproductive system?


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Figure 281

The Male Reproductive SystemThe Male Reproductive System

Pathway of SpermatozoaPathway of SpermatozoaTestisTestis

EpididymisEpididymis

Ductus deferens (vas deferens)Ductus deferens (vas deferens) Ejaculatory ductEjaculatory duct

UrethraUrethra


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Accessory OrgansAccessory Organs

Secrete fluids into ejaculatory ducts andSecrete fluids into ejaculatory ducts and

urethra:urethra:

seminal vesiclesseminal vesicles

prostate glandprostate gland

bulbourethral glandsbulbourethral glands


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External GenitaliaExternal Genitalia

ScrotumScrotum:: encloses testesencloses testes

PenisPenis::

erectile organerectile organ contains distal portion of urethracontains distal portion of urethra


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TestisTestis Is eggIs egg--shapedshaped

5 cm long, 3 cm wide, 2.5 cm thick5 cm long, 3 cm wide, 2.5 cm thick

Weighs 10Weighs 1015 g15 g

Hangs inHangs in scrotumscrotum

TheThe ScrotumScrotum Is a fleshy pouchIs a fleshy pouch

Suspended inferSuspended infer

ior to perineumior to perineum Anterior to anusAnterior to anus

Posterior to base ofPosterior to base ofpenispenis


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The Fetus: Formation of TestesThe Fetus: Formation of TestesTestes form inside body cavity:Testes form inside body cavity:

are adjacent to kidneysare adjacent to kidneys

The Fetus:The Fetus:

Gubernaculum TestisGubernaculum Testis Is a bundle of connectiveIs a bundle of connective

tissue fiberstissue fibers

Extends from testis to pocketsExtends from testis to pockets

of peritoneumof peritoneum Locks testes in position (nearLocks testes in position (near

anterior abdominal wall) asanterior abdominal wall) asfetus growsfetus grows


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Descent of the TestesDescent of the Testes

During seventh month:During seventh month:

fetus grows rapidlyfetus grows rapidly

Circulating hormones:Circulating hormones:

stimulate contraction of gubernaculum testisstimulate contraction of gubernaculum testis

Each testis:Each testis:

moves through abdominal musculaturemoves through abdominal musculature

are accompanied by pockets of peritoneal cavityare accompanied by pockets of peritoneal cavity


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Accessory StructuresAccessory Structures

Accompany testis during descentAccompany testis during descent

Form body ofForm body ofspermatic cordspermatic cord::

ductus deferensductus deferens

testicular blood vessels, nerves, and lymphatictesticular blood vessels, nerves, and lymphatic

vesselsvessels


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Male ReproductiveMale Reproductive

System: An

terior ViewSystem: An

terior View


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TheThe Spermatic CordsSpermatic Cords

Extend between abdominopelvic cavity and testesExtend between abdominopelvic cavity and testes

Consists of layers of fascia and muscleConsists of layers of fascia and muscle

Enclose ductus deferens, blood vessels, nerves, andEnclose ductus deferens, blood vessels, nerves, andlymphatic vessels of testeslymphatic vessels of testes


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Pathway of Spermatic CordPathway of Spermatic Cord Passes throughPasses through inguinal canalinguinal canal

Descends into scrotumDescends into scrotum


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MaleMale Inguinal HerniasInguinal Hernias

Protrusions of visceral tissues into inguinal canalProtrusions of visceral tissues into inguinal canal Spermatic cord (in closed inguinal canal):Spermatic cord (in closed inguinal canal):

causes weak point in abdominal wallcauses weak point in abdominal wall


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TheThe ScrotumScrotum

Is divided into 2 chambers, orIs divided into 2 chambers, or scrotal cavitiesscrotal cavities

Each testis lies in a separate scrotal chamberEach testis lies in a separate scrotal chamber


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TheThe Dartos MuscleDartos Muscle Is a layer of smooth muscle in dermis of scrotumIs a layer of smooth muscle in dermis of scrotum

Causes characteristic wrinkling of scrotal surfaceCauses characteristic wrinkling of scrotal surface


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TheThe Cremaster MuscleCremaster Muscle Is a layer of skeletal muscle deep to dermisIs a layer of skeletal muscle deep to dermis

Tenses scrotum and pulls testes closer to bodyTenses scrotum and pulls testes closer to body(temperature regulation)(temperature regulation)

Normal spermNormal sperm

development indevelopment intestes:testes:

requiresrequires

temperaturestemperatures1.11.1C (2C (2F)F)lower thanlower thanbodybody

temperaturetemperature


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Structure of the TestesStructure of the Testes


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TunicaAlbugineaTunicaAlbuginea

Is a dense layer of connective tissueIs a dense layer of connective tissue

Is rich in collagen fibersIs rich in collagen fibers

Is deep to tunica vaginalisIs deep to tunica vaginalis

Continuous with fibers surroundingContinuous with fibers surrounding

epididymisepididymis

Fibers extend into substance ofFibers extend into substance oftestistestis

Form fibrous partitions, or septa:Form fibrous partitions, or septa:

converge near entrance toconverge near entrance to

epididymisepididymis Supports:Supports:

blood and lymphatic vesselsblood and lymphatic vessels

of testisof testis

efferent ductulesefferent ductules


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The Seminiferous TubulesThe Seminiferous Tubules


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Structures of TestesStructures of Testes Septa subdivide testis intoSepta subdivide testis into lobuleslobules

Lobules contain about 800 slender andLobules contain about 800 slender andtightlytightly--coiledcoiled seminiferous tubulesseminiferous tubules


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Seminiferous TubulesSeminiferous Tubules Produce spermProduce sperm

Each is about 80 cm longEach is about 80 cm longTestis contains about 1/2 mile of tightlyTestis contains about 1/2 mile of tightly--coiledcoiled

seminiferous tubulesseminiferous tubules

Each forms a loop connected toEach forms a loop connected to rete testisrete testis


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Efferent DuctulesEfferent Ductules

151520 large20 large efferent ductulesefferent ductules:: connectconnect rete testisrete testis toto epididymisepididymis


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Interstitial Cells (Interstitial Cells (Cells of LeydigCells of Leydig))

ProduceProduce androgensandrogens::

dominant male sex hormonesdominant male sex hormones

TestosteroneTestosterone:: the most important androgenthe most important androgen


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SpermatogenesisSpermatogenesis Is the processIs the process

of spermof spermproductionproduction

Begins atBegins at

outermost celloutermost celllayer inlayer in

seminiferousseminiferoustubulestubules

ProceedsProceeds

toward lumentoward lumen


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5 Steps in5 Steps inSpermatogenesisSpermatogenesis

1.1. Stem cells (Stem cells (spermatogoniaspermatogonia) divide by) divide bymitosismitosis::

to produce 2 daughter cells:to produce 2 daughter cells:

1 remains as spermatogonium1 remains as spermatogonium

second differentiates intosecond differentiates into primary spermatocyteprimary spermatocyte

2.2. Primary spermatocytesPrimary spermatocytes:: beginbegin meiosismeiosis

formform secondary spermatocytessecondary spermatocytes

3.3.

Secondary spermatocytesSecondary spermatocytes:: differentiate intodifferentiate into spermatidsspermatids (immature gametes)(immature gametes)


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Compartments ofCompartments of

Semin

iferous Tubul

esSemin

iferous Tubul

es OuterOuter basal compartmentbasal compartment::

contains spermatogoniacontains spermatogonia

InnerInner lumenal compartmentlumenal compartment ,or,or adlumenaladlumenalcompartmentcompartment::

where meiosis and spermiogenesis occurwhere meiosis and spermiogenesis occur


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FetalFetalMllerianDuctsMllerianDucts

Help form uterine tubes and uterus in femalesHelp form uterine tubes and uterus in females

In males, inadequate MIF production leads to:In males, inadequate MIF production leads to:

retention of ductsretention of ducts failure of testes to descend into scrotumfailure of testes to descend into scrotum


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The EpididymisThe Epididymis


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Sperm MaturationSperm Maturation

Testes produce physically mature spermatozoa thatTestes produce physically mature spermatozoa thatcan not fertilize an oocytecan not fertilize an oocyte

Other parts of reproductive system are responsibleOther parts of reproductive system are responsible

for:for: functional maturation, nourishment, storage, and transportfunctional maturation, nourishment, storage, and transport

Spermatozoa:Spermatozoa:

detach from sustentacular cellsdetach from sustentacular cells

are free in lumen of seminiferous tubuleare free in lumen of seminiferous tubule

are functionally immatureare functionally immature


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TheThe EpididymisEpididymis

Is the start ofIs the start ofmale reproductive tractmale reproductive tract Is a coiled tube almost 7 m long:Is a coiled tube almost 7 m long:

bound to posterior border of testisbound to posterior border of testis

33Functions of the EpididymisFunctions of the Epididymis

1.1. Monitors and adjusts fluid produced byMonitors and adjusts fluid produced by


2.2. Recycles damaged spermatozoaRecycles damaged spermatozoa

3.3. Stores and protects spermatozoa:Stores and protects spermatozoa:

facilitates functional maturationfacilitates functional maturation


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Spermatozoa LeavingSpermatozoa Leaving

EpididymisEpididymisAre mature, but remain immobileAre mature, but remain immobileTo becomeTo become motilemotile (actively swimming) and functional(actively swimming) and functional

spermatozoa undergospermatozoa undergo capacitationcapacitation

2 Steps in2 Steps inCapacitationCapacitation1.1. Spermatozoa become motile:Spermatozoa become motile:

when mixed with secretions of seminal vesicleswhen mixed with secretions of seminal vesicles

2.2. Spermatozoa become capable of fertilization:Spermatozoa become capable of fertilization:

when exposed to female reproductive tractwhen exposed to female reproductive tract


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The Ductus/Vas DeferensThe Ductus/Vas Deferens

an

d Accessory Glan

dsan

d Accessory Glan

ds


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The Ductus/Vas DeferensThe Ductus/Vas Deferens

an

d Accessory Glan

dsan

d Accessory Glan

ds


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TheThe Ductus/Vas DeferensDuctus/Vas Deferens Also calledAlso calledvas deferensvas deferens

Can store spermatozoa forCan store spermatozoa forseveral months:several months:

in state of suspended animationin state of suspended animation(low metabolic rates)(low metabolic rates)

Is 40Is 4045 cm long45 cm long

Begins at tail of the epididymisBegins at tail of the epididymis

Ascends through inguinal canal:Ascends through inguinal canal: as part of spermatic cordas part of spermatic cord

TT


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TheThe Ejaculatory DuctEjaculatory Duct Is a short passagewayIs a short passageway

(2 cm):(2 cm): at junction ofat junction ofampullaampulla

andand seminal vesicleseminal vesicleductduct

Penetrates wall ofPenetrates wall of

prostate glandprostate gland

Empties intoEmpties into urethraurethra


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The MaleThe Male UrethraUrethra IsIs

used by urinary andused by urinary andreproductive systemsreproductive systems

Extends 18Extends 1820 cm:20 cm:

from urinary bladderfrom urinary bladderto tip of penisto tip of penis

Is divided into 3Is divided into 3

regions:regions: prostaticprostatic

membranousmembranous

spongyspongy


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Seminal FluidSeminal Fluid Is a mixture ofIs a mixture of

secretions from manysecretions from manyglands:glands: each with distinctiveeach with distinctive

biochemicalbiochemicalcharacteristicscharacteristics

Important glandsImportant glandsinclude:include:

seminal vesiclesseminal vesicles prostate glandprostate gland

bulbourethral glandsbulbourethral glands


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4Major Functions ofMale4Major Functions ofMale

GlandsGlands1.1. Activating spermatozoaActivating spermatozoa

2.2. Providing nutrients spermatozoa need forProviding nutrients spermatozoa need formotilitymotility

3.3. Propelling spermatozoa and fluids alongPropelling spermatozoa and fluids along

reproductive tract:reproductive tract:

mainly by peristaltic contractionsmainly by peristaltic contractions

4.4. Producing buffers:Producing buffers:

to counteract acidity of urethral and vaginalto counteract acidity of urethral and vaginalenvironmentsenvironments


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TheThe Seminal VesiclesSeminal Vesicles

Are tubular glands:Are tubular glands: coiled and folded into 5 cm by 2.5 cm masscoiled and folded into 5 cm by 2.5 cm mass

Each gland:Each gland:

is about 5 cm longis about 5 cm long

with short side branches from bodywith short side branches from body

Are extremely active secretory glandsAre extremely active secretory glands

Produce about 60% of semen volumeProduce about 60% of semen volume


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Secretions of Seminal VesiclesSecretions of Seminal Vesicles

Are slightly alkaline:Are slightly alkaline:

to neutralize acids in prostate gland and vaginato neutralize acids in prostate gland and vagina

I

nitiate first step inI

nitiate first step in capacitationcapacitation:: spermatozoa begin beating flagella, become highly motilespermatozoa begin beating flagella, become highly motile

Are discharged into ejaculatory duct atAre discharged into ejaculatory duct at emissionemission::

when peristaltic contractions are underwaywhen peristaltic contractions are underway

Contractions are controlled by sympathetic nervousContractions are controlled by sympathetic nervoussystemsystem

ThTh P Gl dP Gl d


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TheThe Prostate GlandProstate Gland Is a small, muscular organ,Is a small, muscular organ,

about 4 cm diameterabout 4 cm diameter

Encircles proximal portion ofEncircles proximal portion ofurethra below urinary bladderurethra below urinary bladder

Prostatic FluidProstatic Fluid Is slightly acidicIs slightly acidic Forms 20Forms 2030% of semen30% of semen

volumevolume

Contains antibioticContains antibiotic

seminalplasminseminalplasmin Is ejected into prostatic urethra:Is ejected into prostatic urethra:

by peristalsis of prostate wallby peristalsis of prostate wall


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The PenisThe Penis


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The Bulbourethral GlandsThe Bulbourethral Glands Also calledAlso called Cowpers glandsCowpers glands

Are compound, tubuloalveolarAre compound, tubuloalveolarmucous glandsmucous glands Round shaped, up to 10 mmRound shaped, up to 10 mm

diameterdiameter Located at base of penisLocated at base of penis

Covered by fascia of urogenitalCovered by fascia of urogenitaldiaphragmdiaphragm

Secrete thick, alkaline mucus:Secrete thick, alkaline mucus:

helps neutralize urinary acids inhelps neutralize urinary acids in

urethraurethra lubricates thelubricates the glansglans

Duct of each gland:Duct of each gland:

travels alongside penile urethratravels alongside penile urethra

empties into urethral lumenempties into urethral lumen


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Hormonal Feedback/Regulation ofHormonal Feedback/Regulation of

Male Reproductive FunctionMale Reproductive Function

M l HM l H


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Male HormonesMale HormonesAnterior lobe of pituitary gland releases:Anterior lobe of pituitary gland releases:

folliclefolliclestimulating hormonestimulating hormone ((FSHFSH)) luteinizing hormoneluteinizing hormone ((LHLH))

In response to:In response to:

gonadotropingonadotropin--releasing hormonereleasing hormone ((G

nRHG

nRH))GonadotropinGonadotropin--Releasing HormoneReleasing Hormone

Is synthesized in hypothalamus:Is synthesized in hypothalamus:

carried to pituitary by hypophyseal portal systemcarried to pituitary by hypophyseal portal system Is secreted in pulses:Is secreted in pulses:

at 60at 6090 minute intervals90 minute intervals

G RH L lG RH L l


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GnRH LevelsGnRH Levels Control rates ofControl rates of

secretion of:secretion of: FSHFSH andand LHLH

testosterone (releasedtestosterone (releasedin response to LH)in response to LH)


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FSH and TestosteroneFSH and TestosteroneTarget cells ofTarget cells of


These cells:These cells:

promotepromote

spermatogenesis andspermatogenesis andspermiogenesisspermiogenesis

secrete androgensecrete androgen--binding protein (ABP)binding protein (ABP)


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Negative FeedbackNegative Feedback Spermatogenesis isSpermatogenesis is

regulated by:regulated by: GnRH, FSH, andGnRH, FSH, and inhibininhibin

As spermatogenesisAs spermatogenesis

accelerates:accelerates: inhibininhibin secretionsecretion

increasesincreases

Inhibin inhibits FSHInhibin inhibits FSH

production:production: Suppresses secretion ofSuppresses secretion ofGnRH at hypothalamusGnRH at hypothalamus

I hibiI hibi dd FSHFSH


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InhibinInhibin andand FSHFSH Elevated FSH levels:Elevated FSH levels:

increase inhibinincrease inhibinproductionproduction

until FSH returns tountil FSH returns tonormalnormal

If FSH declines:If FSH declines:

inhibin productioninhibin productionfallsfalls

FSH productionFSH productionincreasesincreases


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Luteinizing HormoneLuteinizing HormoneTargets interstitial cells ofTargets interstitial cells of

testestestes Induces secretion of:Induces secretion of:

testosteronetestosterone

otherother androgensandrogens

TestosteroneTestosterone Is the most importantIs the most important

androgenandrogen Has many functionsHas many functions

5 F i f T5 F i f T


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5 Functions of Testosterone5 Functions of Testosterone1.1. Stimulates spermatogenesis:Stimulates spermatogenesis:

promoting functional maturation of spermatozoapromoting functional maturation of spermatozoa2.2. Affects CNS function:Affects CNS function:

libido (sexual drive) and related behaviorslibido (sexual drive) and related behaviors

3.3. Stimulates metabolism:Stimulates metabolism:

especially protein synthesis, blood cell formation andespecially protein synthesis, blood cell formation andmuscle growthmuscle growth

4.4. Est. male secondary sex characteristics:Est. male secondary sex characteristics:

distribution of facial hairdistribution of facial hair increased muscle mass and body sizeincreased muscle mass and body size

characteristic adipose tissue depositscharacteristic adipose tissue deposits

5.5. Maintains accessory glands and organsMaintains accessory glands and organs

T d D lT d D l


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Testosterone and DevelopmentTestosterone and Development Testosterone production:Testosterone production:

begins around seventh week of fetal developmentbegins around seventh week of fetal development

reaches prenatal peak after 6 monthsreaches prenatal peak after 6 months

Secretion of Mllerian inhibiting factor:Secretion of Mllerian inhibiting factor:

by sustentacular cellsby sustentacular cells

leads to regression of Mllerian ductsleads to regression of Mllerian ducts

Early surge in testosterone levels:Early surge in testosterone levels:

stimulates differentiation of male duct system and accessory organsstimulates differentiation of male duct system and accessory organs

affects CNS developmentaffects CNS development

Testosterone programs hypothalamus, controlling:Testosterone programs hypothalamus, controlling:

1.1. GnRH, FSH, and LH secretionGnRH, FSH, and LH secretion

2.2. sexual behaviorssexual behaviors

3.3. sexual drivesexual drive

Reproduction Male

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