Scrotum

The 3 major structures that are contained in the scrotum are…

Spermatic cord, Epididymis, and Testes

The scrotum is divided into 2 sacs by the

median raphe

median raphe

a midline septum that divides the scrotum into right and left halves, each housing one testis

Cremaster Muscle

a suspender muscle consisting of bands of skeletal muscle that arise from the internal oblique muscle of the abdominal wall which elevates the testes

External spermatic fascia

fascial layer derived from the external oblique

Tunica vaginalis

devrived from the peritoneum, composed of 2 layers

the tunica vaginalis separates

scrotal layers from the tunica albunginea

The tunica vaginalis is divided into the

parietal layer and visceral layer

parietal layer of tunica vaginalis

lines walls of scrotal sac

visceral layer of tunica vaginalis

covers testis, epididymis, lower portion of spermatic cord

vaginalis sac

potential space between 2 layers of tunica vaginalis, which normally contains a small amount of fluid

Epididymis

where sperm cells are stored and mature before ejaculation

Seminiferous tubules

where sperm cells are made

Accessory sex glands are

seminal vesicles, prostate gland, and bulbuourethral glands

Tunica albuginea

Dense, fibrous capsule covering testis. Extends inward and divides each testicle into 250-400 lobules

Lobules

internal compartments formed by projections of tunica albuginea.

contains seminiferous tubules and interstitial cells

Seminiferous tubules

produce sperm by spermatogenesis. Each lobule contains 1-3 of these tightly coiled tubules

Sustentacular (Sertoli) Cells

found in tubules and among sperm cells, form the blood-testis barrier need for immunity

Rete testies

seminiferous tubules converge to form this. located at testicular mediastinum

Mediastinum teste

thickened portion of albuginea along posterior border of testes that projects inside it and creates a linear fibrous structure. Point where tubules converge and exit into rete testis and efferent ducts

Appendix testis

a remnant tissue after paramesonephris duct degenerates. small portion at cranial end

Vas Deferens

Muscular cord designed to pump sperm into the prostatic segment of the urethra. Stores sperm up to several months

Spermatic cord

supporting tube of testes. Contains blood vessels, nerves, lymph nodes, cremaster muscle

Epididymis shape

comma shape structure that curves along the posterior border of the testis

The epididymis consists of

Head, body, tail, appendix epididymis, and efferent ductules

Head epididymis

Most superior aspect. Consists of first part of efferent ducts that transports sperm out of testes

Body Epididymis

Contains ductus epididmymis, which is tightly coiled single tube where the efferent ducts empty into

Tail epididymis

distal part of epididymal ducts that exit and continue as the vas deferens in spermatic cord

Appendix epididymis

mesonephric duct persists to form the vas deferens, except for its most cranial position, which becomes this

Efferent ductules

pass from the rete to enter upper portion of the epididymis

Normal shape of testes

Symmetric, oval shaped glands with smooth contour

Location of testes

Each testis lies protected in the scrotum attached to spermatic cord

Upper pole of testes

anterolateral

Lower pole of testes

posteromedial

arterial blood flow to the testes

aorta to testicular artery to capsular arteries to the centripetal arteries

Capsular arteries

run in layer beneath tunica albuginea and surround testis

centripetal arteries

run into testicular parenchyma toward mediastinum

testicular artery

travels in retroperitoneum and enters inguinal canal in spermatic cord

Flow pattern of testes

have low resistance arterial flow

broad systolic peaks and high diastolic flow

Blood flow to scrotum and epididymis

Inferior epigastric artery to the cremasteric artery. Inferior vesicle artery to the deferential artery

Flow pattern of scrotum and epididymis

High resistance arterial flow

narrow systolic peaks and low diastolic flow

Venous blood supply to testes

intratesticular veins to venous outflow to the pampiniform plexus to the internal spermatic vein

The left veins of testes

Left internal spermatic vein to the left renal vein to the IVC

the right veins of testes

right internal spermatic vein to the IVC

Spermatogenesis

sperm formation

Meiosis

nuclear division that occurs in the gonads

product is 4 daughter cells instead of 2

Hormonal regulation of the testicles

involves the brain-testicular axis

Hormonal regulation of spermatogenesis and testicular androgen production involves

hypothalamus, anterior pituitary gland, and testes

The hypothalamus release

GnRH

GnRH

controls release of the anterior pituitary gonadotrophins (FSH and LH)

INDIRECTLY stimulates the testes

FSH stimulates what?

spermatogenesis

LH binds to what

interstitial cells

stimulates them to secrete testosterone

testosterone serves as what

the final trigger for spermatogenesis

by the bloodsteam it exerts a number of effects at other body sites

Negative feedback mechanism

Hypothalamus and anterior pituitary are subject to

feedback inhibition by blood-borne hormones

The amount of testosterone and sperm produced by the testes reflects a balance among what hormones

Gondatrophins, GnRH, Testicular hormones (testosterone and inhibin)

Gonadotrophins

DIRECTLY stimulate the testes

Higher amount of testosterone produced =

increased sperm produced

Scrotum

supporting structure for testes

regulates temperature of testes

Testicles exocrine function

producing spermatoza (male germ cells)

testicles endocrine gland

synthesizing and secreting testosterone

Human chorionic gonadotropin (HCG)

can be produced by tumors which can raise it’s levels in blood

Elevated in seminoma, embryonic cell tumors of testes

Testosterone

main androgen secreted by leydig cells

induces puberty

maintains male secondary sex characteristic

Wall of scrotum normal measurement

2-8mm thick

Cryptochidism

Undescended testis

common etopic locations for cryptochidism

inguinal canal

Concerns for cryptochidism

increased chance of malignancy and infertility

Acute painful scrotum

Most commonly caused by epididymis or orchitis

very common clinical problem in children and adults

Testicular torsion

twisting of the spermatic cord

results in loss of blood supply

Cause of testicular torsion

developmental weakness of mesenteric attachment of spermatic cord to the testis and epididymis

trauma

bell clapper deformity

testicle to fall forward in scrotum and roate freely within the tunica vaginalis. in testicular torsion

Acute testicular torsion

sudden onset of extreme testicular pain

left testicle is more often affected

ultrasound appearance of acute testicular torsion

appearance depends on during of symtoms

testis and epididymis appear enlarged with decreased echogenicity, inhomogenous

complete torsion is identified by

no flow detected on color doppler

chronic testicular torsion

spermatic cord and testicle twist, resulting in ischemia to testicle and complete cessation of blood flow

classified after 10 days. history of severe acute pain in past

ultrasound appearance of chronic torsion

heterogenous, peripheral rim, testicle atrophies. no blood flow

Torsion-Detorsion and Partial torsion

Acute and intermittent sharp testicular pain and scrotal swelling. Twists and untwists. Interspersed with long asymptomatic intervals

Torsion of appendages

loss of blood supply to the appendix testis or appendix epididymis

7-14 years of age

90% of torsed appendages involve appendix testis

on ultrasound torsion of appendages

the testis is normal on color doppler. Could have large circular hyperechoic mass with central hypoechoic area, enlarged circular heterogeneous mass adjacent to a normal testis or epididymis

Testicular rupture

rare, occurs when the capsule, the tunica albuginea is torn by trauma

associated with athletic injuries, industrial or motor vehicle accidents

Epididymitis

Most common cause of acute scrotal illness/pain

What is epididymitis caused by

retrograde spread of bacterial infection from bladder or prostate

associated with prostatitis. Common causes are STDs

Symptoms of epididymitis

fever, chills, enlarged testicle, blood in urine, painful ejaculation, frequent urge to urinate, discharge from penis

Acute epididymitis

enlarged, hypoechoic epididymis, mainly involves the head

chronic epididymitis

thickened echogenic epididymis. may contain calcifications

Orchitis

inflammation of testis due to trauma, metasteses, mumps or other bacterial/viral infection

Isolated orchitis is _______

rare, usually occurs as secondary result of epididymitis

Epididymoorchitis

inflammation of the testis and epididymis

can be focal or diffuse

ultrasound of epididymoorchitis

hypoechoic area extended from epididymal region, increased blood flow in affected testicle and epididymis

Hydrocele

Abnormal collection of serous fluid in potential space between the 2 layers of tunica vaginalis

The most common cause of painless scrotal swelling is

hydrocele

Hydroceles usually occur in what aspect of the scrotum and displace the testis posteriorly

anterior

Ultrasound of hydrocele

anechoic fluid collection, enhanced through transmission, may contain calcifications that produce posterior shadows

Scrotal pearls

AKA Scrotoliths (stones in the scrotum). Calcifications that often result from inflammatory deposits on the tunica vaginalis that have separated from the lining

ultrasound appearance of scrotal pearls

echogenic free-floating calculus outside testicle. appear as echogenic foci between layers of tunica vaginalis

may produce posterior shadow

spermatocele

benign retention cyst arising from the rete testis that connects the testis with the head of epididymis

lies in the head of the epididymis, superior to testis

spermatocele is not

a true cyst

exact cause of spermatoceles is

unknown

symptoms of spermatocles

usually asymptomatic. usually looks like a clear mobile mass located above the testis. discovered usually incidentally

Epididymal cyst

Benign clear serous-containing cysts. usually found in head. Simple fluid

Tubular ectasia of rete testis

dilation of the efferent ductules demonstrating focal enlargement of rete testis due to obstruction level of epididymis