Male Reproductive System

Question 1

Inguinal Hernias, Cryptorchidism, Referred Pain

Answer 1

o Inguinal hernias – loop of intestine descends into scrotal area
o Cryptorchidism – testes remain in abdominal cavity
o Referred pain – kidney disease may manifest as referred pain due to related embryological origin

Question 2

Testicular Capsule

Answer 2

– consists of: visceral tunica vaginalis, tunica albuginea, and tunica vasculosa
o Visceral tunica vaginalis – mesothelial cell layer
o Tunica albuginea – collagen fibers, fibroblasts, nerve endings, and smooth muscle cells
 Branches into septa that provide support for blood vessels; divides testes into 250 lobes
 Mediastinum (rete testes) – thickening of tunica albuginea along posterior border of testes
o Tunica vasculosa – contains blood vessels

Question 3

Interstitium

Answer 3

o Between seminiferous tubules
o Composed of Leydig cells, lymphatics, blood vessels, nerves, loose connective tissue, lymphocytes, mast cells, and macrophages
o Leydig cells – located in the interstitium between seminiferous tubules; produce testosterone stimulated by luteinizing hormone (LH) secreted by anterior pituitary
 Smooth ER, large amount of lipid droplets, & tubular christae mitochondria

Question 4

Seminiferous Tubules

Answer 4

o 1-4 tubules occur in each lobule of testis and exit through rete testis
o Each tubule surrounded by tunica propria (boundary tissue)
o Basement membrane made of basal lamina&lamina reticularis underlies seminiferous epithelium
 Clinical correlation: vasectomized men have thickened and convoluted basement membrane surrounding the seminiferous tubules
o Germ cells and Sertoli cells line the seminiferous epithelium
 Complex stratified epithelium
 “transitional” zone (terminal segment) at end of each seminiferous tubule contains ONLY Sertoli cells

Question 5

Sertoli and Germ Cells

Answer 5

o Sertoli Cells – respond to follicle stimulating hormone (FSH) and support spermatogenesis
 Surrounded by germ line cells at various stages of differentiation
 Diploid(2n) and terminally differentiated
 If they are not present  male is infertile
 Tight junctions between Sertoli cells provide blood-testis barrier
• Divide seminiferous epithelium into two functionally distinct compartments
o Basal compartment – contains spermatagonia and early primary spermatocytes
o Adluminal compartment – contains primary spermatocytes, secondary spermatocytes, and differentiating spermatids
 Proteins in blood cannot penetrate beyond blood testis barrier; therefore Sertoli cells regulate transport of compounds from blood to adluminal compartment and add compounds of their own during nurture of germ cells
o Germ Cells – cells actually undergoing mitosis and meisosis in order to become sperm cells

Question 6

Testosterone Functions

Answer 6

o Required for proper spermatogenesis
o Maintain integrity of accessory glands (especially prostate)
o Responsible for secondary sex characteristics
o Responsible for libido (sex drive)

Question 7

Spermatogenesis Anatomy

Answer 7

seminiferous tubules  rete testes  vas (ductus) deferens  urethra
o Glands: seminal vesicles, prostate glands, and bulbo-urethral glands

Question 8

Spermatogeneis Mechanism

Answer 8

– occurs within the germ cells and is the process of diploid spermatagonia becoming haploid spermatozoa; once it starts it cannot stop
o Lasts 74 days
o Begins with primitive type A spermatogonium containing 46 chromosomes (2n)
o Type A divide to yield type B spermatogonia (2n)
o Type B undergoes several rounds of mitosis to yield tetraploid (4n) primary spermatocytes (large nuclei)
o Primary spermatocytes undergo meiosis to form secondary spermatocytes (2n)
o 2o spermatocytes rapidly undergo 2nd meisosis  spermatids (1n) (round cells w/ small nuclei)

Question 9

Spermiogenesis Mechanism

Answer 9

– maturation process; newly formed round spermatids differentiate to form spermatozoa
o Acrosomal cap - golgi apparatus & granules migrate to one end of nucleus w/ enzymes (acrosin, hyaluronidase, neuraminidase) that facilitate penetration of zona pellucida during fertilization
o Organization of mitochondria distal to the nuclei and acrosomal cap at base of microtubules
o Formation of microtubule axoneme (9+2) doublet tail for motility
o Removal of excess cytoplasm (residual body)
o Spermatids will move from basolateral side of sertoli cell to luminal side

Question 10

Germ Cell Clinical Relevance

Answer 10

o Sertoli cell only syndrome – infertility caused by aspermatogenesis (absence of germ cells)
o Irradiation to the testes may cause complete loss of germ cells and infertility

Question 11

Spermatozoa Structure

Answer 11

o Head – mostly condensed nucleus, haploid DNA, acrosomal cap; DNA more condensed than in any other cell/somatic cell in body
o Mid-piece – made of 9-2 doublet of microtubules (axoneme) surrounded by layer of 9 course fibers; mitochondria surround the course fibers to provide energy
o Principal piece –axoneme with fibrous sheath and plasma membrane (NO mitochondria)
o End-piece – axoneme surrounded by plasma membrane

Question 12

Stages of Seminiferous Epithelium

Answer 12

o 6 Stages/Associations are in sequential temporal succession that are in spiral pattern
o Each stage is characterized by the existence of certain cell types
o Same generation germ cells connected by cytoplasmic bridges due to incomplete cytokinesis

Question 13

Testis Clinical Relevance

Answer 13

o Normal spermatogenesis may be prevented by excessive temperature
o Orchitis (inflammation of testis) is a common complication of mumps; may raise pressure within the testis leading to atrophy of seminiferous tubules and eventual sterility
o Testicular cancers are most prevalent under age of 40; 4 major pathologies and almost always malignant; cured nearly 90% of time

Question 14

Excurrent Ducts

Answer 14

– morphologically, physiologically, and biochemically modifies sperm
o 2,000 sperm produced per second but sperm released from testis are unable to fertilize an ova
o Made up of several histologically distinct regions – tubulus rectus  rete testis  ductuli efferentes  ductus epididymidis  ductus deferens  and ampulla

Question 15

Intratesticular Excurrent Ducts

Answer 15

– tubulus rectus, rete testis, and 1st part of ductuli efferentes
o Tubulus rectus – lined by cuboidal epithelium with occasional single cilium
o Rete testis-embedded in mediastinum; simple cuboidal epithelium w/ occasional single cilium
o Sperm then travel through efferent ducts to the epididymis

Question 16

Ductus Efferentes

Answer 16

o Derived from mesonephric tubules and therefore have similar function (reabsorb fluid)
o 20 ducts per testis will enter efferent duct
o Ciliated cells aid in movement; non-ciliated cells involved with reabsorption of fluid
o Reabsorbs 95% of fluid resulting in concentration of sperm
o Fluid with sperm moves through ducts via:
 Hydrostatic pressure generated from testis
 Beating of cilia on ciliated cells
 Peristaltic contraction of periductal smooth mucle cells around the ductuli

Question 17

Ductus Epididymis

Answer 17

o Derived from mesonephric duct
o Receives concentrated fluid/sperm from ductuli efferentes
o 6 meters long with 3 distinct regions: caput (head), corpus (body), cauda (tail)
 Head – adjacent to the efferent ducts
 Tail – storage of sperm
o Lined by pseudostratified columnar epithelium – principal cells with steroecilia (act like villi) that contain actin filaments that are not motile; serve to increase the surface area for reabsorption
 Abundant in golgi apparatus
 Involved in protein secretion associated with sperm maturation and Resorption
o Also lined by periductal smooth muscle that can propel sperm via peristaltic contractions
o Experiment: if you take sperm from head of epididymis it cannot fertilize an egg but taking sperm from tail portion is able to fertilize egg  proof that maturation of sperm occurs within epididymis and is necessary for mature sperm

Question 18

Epdidymis Clinical Relevance

Answer 18

o Sperm maturation involved chemical interation of sperm and epithelium of epididymis
o Infection of epididymis common after puberty and can be caused by gonococcal or nonspecific infection usually from retrograde flow beginning in urethra

Question 19

Ductus (Vas) Deferens

Answer 19

– continuous with cauda (tail) epididymis connecting sperm storage region to rest of male accessory glands
o Lined by psuedostratified columnar epithelium covered with stereocilia
o Surrounded by 3 layers of smooth muscle cells and connective tissue (inner longitudinal, middle circular, and outer longitudinal)
o Folds protrude into the lumen; become more prominent and numerous farther down the tubule

Question 20

Ductus (vas) Deferens Clinical Relevance

Answer 20

o Vasectomy – form of male contraception; ligation of vas deferens via removal of section of tube or tying the tube with a suture
o Can be re-anastomosed (vasovasotomy) following vasectomy, chances of fertility returning to patient declines with increased length of time between the two procedures

Question 21

Ampulla

Answer 21

o Terminal dilated region of vas deferens that is behind the bladder and joins the duct of seminal vesicle to form ejaculatory duct that enters into the prostatic urethra
o Branched and highly folded with protrusions into lumen

Question 22

Seminal Vesicles

Answer 22

– NO sperm stored (name is misleading)
o Join ampulla at distal extremity to form ejaculatory duct which enters prostatic urethra
o Paired consisting of single highly convoluted duct enclosed in lamina propria w/ smooth muscle
o Pseudostratified/simple columnar epithelium lining the seminal vesicles is highly folded to increase the area for secretion
o Secretory gland that expels secretions via contraction of smooth muscle cells

Question 23

Verumontanum

Answer 23

– entrance of ejaculatory ducts and urethra; landmark in prostate gland

Question 24

Prostate

Answer 24

– chestnut shaped organ; posterior to the bladder
o Hard structure enclosed in fibro-elastic capsule
o Organized into 3 branched glands around the urethra: main glands, submucosal, and mucosal
o 30-50 branched tubule-alveolar glands empty into the urethra
o Simple columnar or pseudostratified
o Each gland surrounded by fibromuscular stroma that aids in ejaculatory discharge of fluid
o Prostatic fluid constitutes 50-75% of ejaculate volume
 Proteolytic enzymes, zinc, citric acid, acid phosphatase, and PSA
o Divided into 3 zones based on distance from urethra
 Periurethral zone – commone site for Benign Prostatic Hyperplasia – causes compression of urthra and difficulty urinating; NOT cancerous; 5 pathologies all involving stromal overgrowth often with secondary reactivation of epithelial proliferation
 Central zone – common zone for development of prostate cancer
• Second leading cause of cancer death in men (9%)
• Incidence increases with age; primarily over 60yo; 2x more common in blacks
o Corpora amylacea – prostatic concretions that occur in older men and obstruct lumen of ducts
o Every man will develop prostate cancer to some degree if they live long enough
 PSA blood tests done to test for prostate cancer has lead to earlier diagnosis
• PSA > 4.0  further testing should be done

Question 25

Bulbo-Urethral (Cowper’s Glands)

Answer 25

o Small paired glands on either side of urethra just as it enters the base of the penis
o Enclosed in smooth muscular sheath and pack with tubule-alveolar glands that secrete mucin (sialoglycoprotein) that acts as lubricant of the penile urethra prior to ejaculation
o Connective tissue contains smooth and skeletal muscle – only place in body where skeletal muscle will be in close proximity to an alveolar gland

Question 26

Penis

Answer 26

o Consists of urethra and 3 parallel cavernous bodies (vascular structures)
 2 paired corpus cavernosa lie dorsally – engorge with blood during sexual arousal
 Corpus spongiosum (aka corpus cavernosa urethrae) on ventral side surrounding urethra; begins at base of penis as expanded bulbous portion and terminates as the glans penis
o Fibroelastic connective tissue layer (tunica albuginea) surrounds the corpus cavernosa and forms septum in midline that is incomplete in distal region to allow equilibration of blood flow between the two corpora cavernosa

Question 27

Penis Clinical Relevance

Answer 27

o Impotence is inability to achieve erection; may manifest of neurological/emotional dysfuntion or congenital circulatory disorders of the penis
o Infections include various venereal disease

Question 28

Urethra

Answer 28

o Extends from bladder to external meatus on glans of penis
o Divided into 3 parts
 Prostatic urethra – exits the bladder and enters prostate; lined by transitional epithelium
 Membranous urethra – connects prostatic urethra to spongy urethra and exits within the urogenital diaphragm; lined by stratified or pseudostratified columnar epithelium
 Penile urethra – enters the penis; lined by stratified columnar epithelium
o Urethral glands are in submucosal connective tissue
o Infections of urethra (E.coli) can retrograde to infect bladder, seminal vesicles, and epididymis

Question 29

Pinaform Plexus

Answer 29

o Pinaform plexus – uses counter current exchange with arteries supplying testes to lower the temperature of blood delivered to the testis and warm blood prior to returning to circulation