MALE REPRODUCTIVE ANATOMY
Seminal vesicles
5 cm long glands
between bladder fundus and rectum (rectovesicle pouch and the rectoprostatic fascia)
combine with vas deferens to form the ejaculatory duct -> drain into the prostatic urethra
honeycomb; lobuled structure with mucosa lines pseudostratified columnar epithelium; highly influenced by testosterone; growing taller with high levels
responsible for production of seminal secretions
Embryology: SEED (derived from mesonephric ducts)
Seminal glands
Ejaculatory ducts
Epididymis
Ductus (vas deferens)
Secretions included in late ejaculate fractions
Alkaline fluid -> neutralises the acidity of the male urethra and vagina in order to facilitate the survival of spermatozoa
Fructose -> provides an energty source for spermatozoa
Prostaglandins -> have a role in suppressing the female immune response to foreign semen
Clotting factors -> designed to keep semen in the female reproductive tract post-ejaculation
Remaining volume is made up of testicular spermatozoa, prostatic secretions and mucus from the bulbourethral gland
Neurovasculatore
internal iliac artery: internal pudendal and middle rectal arteries
sympathetic
external and internal iliac lymph nodes
Bulbourethral glands
Cowper’s glands
Pea shaped exocrine glands located posterolateral to the membranous urethra superiorly to the bulb of the penis
producing a lubricating mucus secretion (containing glycoproteins
deep perineal pouch
open into the proximal portion of the spongy urethra
compound tubulo-alveolar glands lined by columnar epithelium
development greatly influenced by DHT (dihydrotestosterone) (derived from urogenital sinus)
The mucus
lubrincation
pre-ejaculate; prepares a clean and lubricated pathway for ejaculation; usually devoid of any spermatozoa (sometimes present)
Vasculature and innervation
arteries to the bulb of penis
hypogastric nerve, pelvic nerve and pelvic branch of pudendal nerve
internal and external iliac lymph nodes
Prostate
largest accessory gland in the male reproductive system
inferior to the neck of the bladder and superiorly to the external urethral sphincter (levator ani muscle lying inferolaterally)
prostatic glands take the proteolytic enzymes secrete them immediately before ejaculation (10-12 openings on each side)
size of a walnut
two-thirds of the prostate is glandular in structure and the remaining third is fibromuscular
surrounded by fibrous capsule of the prostate; not real capsule
3 zones:
central zone -> surrounds ejaculatory ducts, comprising approx. 25% of normal prostate volume (empty obliquely in the prostatic urethra)
Transitional zone -> located centrally; surrounds urethra, 5-10% of prostate vol; glands typically undergo benign hyperplasia (BPH)
Peripheral zone -> main body of the gland; high incidence of acute and chronic inflammation; high rate of prostate carcinoma at the peripheral zone; felt agains the rectum on DRE
fibromuscular stroma -> (fourth zone?) anterior; merges with tissue of the urogenital diaphram
neurovascular
prostatic arteries; from internal iliac arteries
prostatic venous plexus
inferior hypogastric plexus
neurovascular bundles
The spermatic cord
begins in inferior abdomen and ending in the scrotum
formed at the opening of the inguinal canal (deep inguinal ring); laterally to the inferior epigastric vesels
cord passes through the inguinal canal entering the scrotum via the superficial inguinal canal
Fascial covering
External spermatic fascia -> derived from deep subcutaneus fascia (fascia innominata)
Cremaster muscle and fascia -> derived from the internal oblique muscle and its fascial coverings; forms the middle layer of the spermatic cord fascia. It is adiscontinuous layer of striated muscle that is orientated longitudinally
Internal spermatic fascia -> derived from the transversalis fascia
contents:
blood vessels (testicular artery
cremasteric artery and vein
artery to vas deferens
pampiform plexus of testicular veins
Nerves: genital branch of genitofemoral nerve; autonomic nerves
Other: Vas deferens (sperm from epididymis to the ampulla); Processus vaginalis (projection of peritoneum that forms the pathway of descent for the testes during embryonic development (in adults closed shut))
lymph vessels -> drain into the para-aortic nodes, lumbar region
Pampiform plexus: network of veins; venous drainage of testes; wrapping itself around testicular artery
acts as heat exchanger; cooling arterial blood
right drains into IVC; left into left renal vein
Vas Deferens
straight, thick muscular tube that conveys sperm from the epididymis to the ampulla ( then to ejeculatory duct)
Lots of smooth mauscle arranged in 3 layers (longitudinal, circular, longitudinal
The scrotum
fibromuscular cutaneous sac; between penis and anus
derived from paired genital swellings; biologically homologous to the labia majora
Contents:
testis -> site of sperm production
Epididymis -> situated at the head of each testicle; functions as a storage reservoir for sperm
Spermatic cord -. a collection of muscle fibres, vessels, nerves and ducts that run to and from the testes
+ muscle fibres; dartos muscle (sheet of smooth muscle; help regulate the temperature of the scrotum, wrinkling skin; decreases surface area, reducing heat loss
neurovascular supply
vessles: anterior and posteriol scrotal arteries
scrotal veins
anterior and anterolateral aspect of scrotal nerves; posterior aspect (posterior scrotal nerves derived from the perineal branches of pudendal nerve and posterior femoral cutaneous nerve
lymphatics -> superficial inguinal nodes
The testes and epididymis
paired structures within the scrotum; epididymis situated on the posterolateral aspect of each testicle
left testicle lower than the right; suspended from the abdomen by the spermatic cord
Originally located on the posterior abdominal wall; during embryonic development they descend down the abdomen through the inguinal canal to reach scrotum; they carry their neurovascular and lymphatic supply with them
sperm production and hormone synthesis; epididymis acts as storage
testes have an ellipsoid shape; series of lobules; each containing seminiferous tubules supported by interstitial tissue; lined by Sertoli cells (aid maturation process of spermatozoa)
Leydig cells responsible for testosterone production
Developing sperm travels through the tubules collecting in the rete testes; efferent tubules transport the sperm from the rete testes to the epididymis for storage and maturation.
inside scrotum, testes covered almost entirely by tunica vaginalis (closed sac of parietal peritoneal origin that contains a small amount of viscous fluid) it lubricates the surfaces of the testes and allowing for friction-free movement
testcular perenchymaprotected by tunica albuginea (a fibrous capsule the encloses testes, divides it into tubules)
Epididymis
Head -> most proximal part; formed by efferent tubules of the testes, which transport sperm from the testes to the epididymis
Body -> formed by the heavily coiled duct of the epididymis
Tail -> most distal part; marks the origin of the vas deferens, transport sperm to the prostatic portion of the urethra for ejaculation
Innervation -> testicular plexus; autonomic and sensory fibres
vascular supply -> testicular arteries; arise from the abdominal aorta (via inguinal canal)
cremasteric artery and artery of the vas deferens; give anastamoses to the main testicular artery
paired testicular veins; from pampiniform plexus
lymphatics -> lumbar and para-aortic nodes
The penis
sexual intercourse -> during erotic stimulation; undergoes erection; engorged with blood; ejaculation occurs; undergoes remission returning to a flaccid state
micturition -> penis important urinary role
Root -> most proximal, fixed part; located in the superficial perineal pouch of pelvic floor; not visible externally; contains tree erectile tissues (two crura and bulb) two muscles (ischiocavernosus and bulbospongiosus)
Body -> free part of the penis, between the root and glans; suspended from the pubic symphysis; composed of tree cylinders of erectile tissue: two corpora cavernosa and the corpus spongiosum
Glans -> most distal part; conical in shape; distal expansion of the corpus spongiosum; opening of urethra, termed the external urethral orifice
Erectile tissues
erectile tissues fill with blood during sexual arousal producing erection
left and right crura and the bulb of the penis; located laterally -> later form corpora cavernosa; separated by the spetum of the penis; often incompletely
bulb situated in the midline of penile root transversed by the urethra; later forms corpus spongiosum (ventral); male urethra runs through corpus spongiosum to prevent it becoming occluded during erection the corpus spongiosum fills to a reduced pressure
Muscles
bulbospongiosus (X2) -> associated with the bulb of penis; contracts to empty the spongy urethra of any residual semen and urine; anterior fibres aid in maintaining erection by increasing the pressure in the bulb of the penis
Ischiocavernosus (X2) -> surrounds the left and right cura of the penis; contracts to force blood from the cavernous spaces in the crura into the corpus cavernosa - helps maintain erection
Fascia coverings
two fascial coverings; most superficial layer, immediately under the skin -> external fascia of Colles (continuity with the fascia of Scapa which covers the abdominal wall)
deep fascia of the epnis (Buck’s fascia) continuation of the deep perineal fascia; strong membranous covering which holds all three erectile tissues together.
Ligaments
Suspensory ligament– a condensation of deep fascia. It connects the erectile bodies of the penis to the pubic symphysis.
Fundiform ligament– a condensation of abdominal subcutaneous tissue. It runs down from the linea alba, surrounding the penis like a sling, and attaching to the pubic symphysis.
Skin
more heavily pigmented than rest of the body; connected to the underlying fascias by loose connective tissue
prepuce (foreskin) is a double layer of skin and fascia; located at the neck of the glans; covers the glans to a variable extent; connected to the surface of the glands by the frenulum; a median fold of skin on the ventral surface of the penis; the potential space between the glans and prepuce is termed the preputial sac
Neurovascular supply
dorsal arteries of the penis
Deep arteries of the penis
Bulbourethral artery
All branches of the internal pudendal artery
Drained by paired veins; cavernous spaces are drained by the deep dorsal vein of the penis -> empties into the prostatic venous plexus; superficial dorsal veins
Innervation -> S2-S4 segments and spinal ganglia
pudendal nerve
Periprostatic nerve plexus
