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Reproductive System (Male)

Reproductive System

The reproductive system of both the maleand female have the same basiccomponents:

1. or sexual organs -produce the gametes (sex cells) and

hormones.2. Reproductive tract - ducts and organs thatreceive, store and transport gametes.3. - secrete fluids thatsupport the transmission of gametes fromthe male to the female.4. External genitalia - external organs thatenable transmission of male gametes from

the male to the female reproductive tract.


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1. Gonads

2. Accessory Glands


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Testes (sing. testis)The are ovoid organs located

in an external pouch called the .Descent of the Testes

The testes first appear in the body cavity at alocation where the kidneys will come to lie butduring development the testes come to liewithin the scrotum.

The pathway of descent is indicated by a foldof peritoneum called the thatattaches the inferior pole of the testis to thelocation where the scrotum will develop.

The actual descent of the testes is the result oftwo processes:

1. The testes remain in position while thesurrounding structures grow rapidly.

2. The inferior part of thedevelops into a thatcontracts during the last two months ofgestation and pulls the testes into the outpocketing of the peritoneal cavity thatbecomes the scrotum.


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1. Testes

2. Gubernaculum

3. Gubernaculum

4. Fibromuscular Cord


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Gubernaculum


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Spermatic Cords

The form during the

descent of the testis.

The spermatic cords contain the, the , the

, the andlymphatic vessels. In addition, thespermatic cord is held together by layers of

, connective tissue and muscle.

The spermatic cord enters the scrotumthrough the passingthrough the deep to enterthe canal from the peritoneal cavity and

exiting through theto enter the scrotum.


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1. Spermatic Cords

2. Ductus Deferens, Testicular Artery,

Pampiniform Plexus andGenitofermoral Nerves

3. Fascia

4. Inguinal Canal, Deep Inguinal Ring,Superficial Inguinal Ring


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Scrotum and Position of the Testes

Each testis is within a separate

.

The wall between the two scrotalcavities is indicated on the exterior ofthe scrotum by the .

The scrotal cavities are lined by aserous membrane called the

.


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1. Scrotal Cavity

2. Perineal Raphe

3. Tunica Vaginalis


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The placement of the testes in the scrotumprovides an environment that is 2 degreescentigrade less warm than that inside thebody. Keeping the testes at this cooler

temperature is essential for the properfunction of the testes. Two muscles help toensure that the testes remain at theappropriate temperature:

1.

The is smooth muscle that isfound in the under the thinskin of the scrotum. Contraction of thegives the scrotal skin its wrinkled appearanceand decreases the surface area by which

heat is lost.2.The is a continuation

of the muscle through thecanal. It lies between the

fascia and the parietal layer of the. Contraction of the muscles draw the

scrotum closer to the body and increases thetesticular temperature while relaxation of themuscle allows the scrotum to hang moreloosely and decreases testicular temperature.


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1. Dartos, Dartos, Superficial Fascia,Dartos

2. Cremaster Muscle, Cremaster Muscle,internal oblique muscle, Inguinal Canal,Superficial Fascia, Tunica Vaginalis


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Histology of Testis

The testis is surrounded by a thick

connective tissue capsule called the. On the posterior aspect of

the testis the connective tissue extendsinto the testis and forms the .The interior of the testis is divided into

compartments called byconnective tissue partitions calledthat extend from the tunica albuginea.


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1. Tunica Albuginea

2. Mediastinum

3. Lobules

4. Septa


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Each lobule contains one to three tightly

coiled .

The are u-shapedwith each end of the tubule connected to a

that enters the

mediastinum.

Within the , the straighttubules open into a complex maze ofinterconnected tubules called the

.

The rete testis is connected to theepididymis by 20 .


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1. Seminiferous Tubules

2. Seminiferous Tubules,Straight Tubules

3. Mediastinum, Rete Testis

4. Efferent Ductules


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A thin capsule forms the wall of the

. The connectivetissue between the tubules containblood vessels and .

The produce the male

sex hormones, the androgens, ofwhich the most important is .


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1. Seminiferous Tubules

2. Interstitial Cells

3. Interstitial Cells

4. Testerone


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Spermatogenesis

is the process by

which stem cells called(sing. spermatogonium) become spermcells or . This processinvolves meiosis in which a cell containinga pair of each type of chromosome

( ) divides twice to produce four cellscontaining a single chromosome of eachtype ( ).


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1. Spermatogenesis

2. Spermatogonia

3. Spermatozoa

4. Diploid

5. Haploid


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The divides bymitosis to produce cells that committo meiosis while retaining some cellsas future stem cells.

The undergo a number

of mitotic divisions until the cells thatwill undergo meiosis,, are produced.


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1. Spermatogonium

2. Spermatogonia

2. Primary Spermatocytes


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The primary spermatocyte undergoesthe first division of meiosis (reduction

division) and produces twowhich contain a single

chromosome of each type ( ).

Each chromosome has two copies

(chromatids) connected by a .Each secondary spermatocyte quicklyundergoes the second division of meiosis(replication division) to produce four

.


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1. secondary spermatocytes2. Haploid3. Centromere

4. Spermatids


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The process by which the spermatidbecomes a mature male gamete called a

(plural: spermatozoa) is called.


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1. spermatozoon

2. spermiogenesis


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The spermatozoon has three distinctregions:1. HeadThe head contains a flattened oval

nucleus that contains densely packedchromosomes. The tip is covered by anenzyme-filled vesicle called the

.2. Middle PieceThe middle piece is connected to the

head by the neck that contains thethat form the basal body of the

flagellum. Within the middle piece,numerous that provide theenergy for motility are arranged in a

spiral fashion.3. TailThe tail represents a continuation of the

flagellum beyond the middle piece.


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1. Acrosomal Cap

2. Centrioles

3. Mitochondria


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Sustentacular Cells (Sertoli Cells)Nurse Cells

The extend the full thickness ofthe wall of the seminiferous tubules from the

to the lumen. These cells serve a numberof essential functions:

1. Maintenance of the Blood-Testis BarrierThis barrier separates the fluid within the lumen of

the tubules from the surrounding interstitial fluid and

thereby preserves its unique characteristics. Thebarrier is also essential for preventing cells of theimmune system from attacking the unique cells thatresult from meiosis. These cells contain moleculesthat would be recognized as foreign.

2. Support SpermatogenesisSustentacular cells provide metabolic support for

spermatogenesis.3. Support of Spermiogenesis

The developing spermatids remain attached tosustentacular cells until they are mature enough todetach.

4. Secretion ofSustentacular cells moderate the rate of

spermatogenesis by secreting inhibin which inhibits

secretion of the hormones that stimulate the process(negative feedback).

5. Secretion of Androgen-Binding ProteinSecretion of androgen-binding protein increases

the concentration of in the tubules to

levels necessary to stimulate sperm cell production.


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1. Sustentacular Cells (Sertoli Cells)

Nurse Cells

2. Basal Lamina

3. Inhibin

4. Androgen


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Male Reproductive TractThe male reproductive tract stores,

nourishes and transports the spermatozoawhile promoting their maturation.

The lies along the posteriorborder of the testis. It is a long (7 m or23 ft) tightly coiled tubule lined by a

simple columnar epithelium with longmicrovilli called . Theepididymis is divided into threesegments:

1. Head - This segment incorporates theefferent and lies on the superior pole ofthe testis.2. Body - The body extends inferiorlyfrom the last efferent ductule along theposterior surface of the testis.3. Tail - The tail is located on the

and is the principal storagesite for sperm.


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1. Epididymis

2. Stereocilia

3. Inferior Pole


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The three main functions of the

are:

1. Adjusts the composition of thefluid produced by the seminiferoustubules.

2. Absorbs and recycles defectivesperm cells and cellular debris.

3. Stores spermatozoa while

facilitating their maturation.


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Epididymis


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The extends from

the tail of the epididymis through theinguinal canal as part of the

and enters the abdominal cavity.In the abdominal cavity the duct archesover the urinary bladder in between the

ureters and reaches the prostate gland.The expanded portion of the ductbefore it reaches the prostate is calledthe .


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1.Ductus Deferens (Vas Deferens)

2. Spermatic Cord

3. Ampulla


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During ejaculation the thickmuscular layer undergoes

which propel thespermatozoa along the duct. At the

, the ductus deferensunites with the duct of the seminalvesicles to form the

which is found within the prostategland.


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1. peristaltic contraction

2. Prostate

3. Ejaculatory Duct


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The in themale is the final

passageway for theurinary and reproductivesystems and was covered

with the urinary system.


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Urethra


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Theaccount for about 95% of

the volume of the semen.


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Accessory Glands


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The are highly coiledtubular glands located on the posteriorwall of the urinary bladder. The seminalvesicles contribute about 60% of thevolume of the semen. The secretion ofthe gland includes , clottingproteins, and fructose.


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1. Seminal Vessicles

2. Prostaglandins


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The is a small,muscular, round organ that encirclesthe urethra as it exits the urinarybladder. The gland produces asecretion that contributes 20-30

percent to the volume of the semen.The secretion includes ,an antibiotic substance that mayprevent urinary tract infections.


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1. Prostate Gland

2. seminalplasmin


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These are small paired organs foundin the urogenital diaphragm at thebase of the penis. These glandsproduce a thick, sticky,

that neutralizes the acidity of theurethra and lubricates the tip of thepenis.


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1. Bulbourethral Gland (Cowper's Gland)

2. alkaline mucus


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The is a tubularorgan that introduces

semen into the femalevagina during sexualintercourse. It can bedivided into threeregions:

1. - The fixedportion of the peniswhich is attached to thepelvic bone.2. (Shaft) - This

is the tubular, moveableportion of the penis.3. - This is theexpanded distal endthat surrounds the

external urethral orifice.A fold of skin called the

(foreskin)attaches to the glans ofthe penis.


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1. Penis

2. Root

3. Body

4. Glans

5.Prepuce


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The penis contains three cylindricalbodies of erectile tissue:

These are a pair of cylindrical

bodies in the upper portion of theshaft that are separated by a thin

partition and are encapsulated bydense connective tissue. At the rootof the penis the

divide to form the(legs) that attach to the pelvic bone

by ligaments.


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1.Corpora cavernosa2. crura


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This body is a single cylindricalbody that surrounds the spongy, orpenile, urethra. The proximalportion of the corpus spongiosumexpands to form the ofthe penis. The distal expanded endof the body is the glans.


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1. Corpusspongiosum

2. Bulb

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