Male Reproductive System

There are 3 columns of erectile tissue in the penis. What are they

Corpus Spongiosum (urethra)

2 Corpra Cavernosa

What’s that & what does it do

The penile suspensory ligament (PSL) supports and maintains the erect penis in an upright position during sexual intercourse

Seminiferous tubules are the site of what process

Germ Cell Production

Leydig cells function

testosterone production

What sits between the seminiferous tubules

Interstitial cells of Leydig

Name the 2 main types of cells in seminiferous tubules & give their function

Spermatogonia: Stem cells involved in spermatogenesis

Sustentacular cells (Sertoli): Sustain and promote development of sperm

Spermatogenesis involves three processes. What are they

Mitosis

Meiosis

Spermiogenesis

Structure of a spermatozoon (fully mature male gamete)

The acrosomal cap on the spermatozoon is derived from what

Golgi

epididymis role

Elongated tubule with head, body and tail regions

Monitors and adjusts fluid in seminiferous tubules

Stores and protects spermatozoa

Facilitates functional maturation of spermatozoa

Ductus (vas) deferens path & structure

Begins at epididymis

Passes through inguinal canal

Enlarges to form ampulla

Ejaculatory duct at base of seminal vesicle and ampulla

Empties into urethra

Urethra path & region names

Urinary bladder → tip of penis

3 regions

• Prostatic (most distensible)

• Membranous

• Penile

Typical ejaculate is how many ml of fluid

2-5ml

What percentage of semen comes from where

What do the seminal vesicles contribute to semen

Secretions contain fructose, prostaglandins & fibrinogen

What does the prostate contribute to semen

Proteolytic enzymes

Prostatic acid phosphatase

Prostate specific antigen

What do the bulbourethral glands contribute to semen

Secrete alkaline mucus with lubricating properties

What do the right & left gonadal veins generally drain into & how often does this actually occur (%)

Right gonadal vein drains directly into the IVC (seen in 78%).

Left gonadal vein drains into the left renal vein (seen in 79%).

About ___% of right and ___% of left gonadal veins show different drainage patterns than the classic RHS → IVC, LHS → L renal

About 22% of right and 21% of left gonadal veins show different drainage patterns.

Prevalence of variances in drainage pattern of the right gonadal vein

Prevalence of variances in drainage pattern of the left gonadal vein

What type of innervation does the pudendal nerve (in the lumbosacral plexus) provide?

Somatic innervation (motor and sensory)

Which spinal cord levels give rise to sympathetic innervation of the epididymis, vas deferens, seminal vesicles, and prostate gland

T12–L2

Pathway of T12-L2 nerves to the hypogastric plexus

The axons pass through the sympathetic chain, exit in the lumbar splanchnic nerves, and synapse on the neurons in the inferior mesenteric ganglion.

The postganglionic axons reach target tissues in the male reproductive system via hypogastric plexuses

Some preganglionic fibres from L1-L2 spinal segments descend in the sympathetic chain and synapse on postganglionic neurons in the hypogastric plexus.

The postganglionic fibres from these neurons then innervate the male erectile tissue

What is the effect of sympathetic activation on male reproductive organs

Ejaculation of spermatozoa and secretions from the prostate and seminal vesicles

Which spinal cord levels provide parasympathetic innervation to male erectile tissue?

S2–S4

Pathway of parasympathetic fibres to erectile tissue

The parasympathetic preganglionic fibres exit from the ventral roots, travel in the pelvic nerves, pass through the hypogastric plexus, and are distributed to the erectile tissue.

Activation of the parasympathetic nervous system results in what

the dilation of the arteries and increased blood flow in the corpora cavernosa causing erection of the male sexual organ

At what stage of development are the testes usually in the scrotum

8 lunar months (8th month of pregnancy)

Explain the level of Testicular Descent at 8 weeks

8 weeks (22.5 mm crown-rump)

Testes (gonads) develop high on the posterior abdominal wall.

Positioned near the suprarenal gland and kidney.

Connected to the future scrotal region by the gubernaculum.

Suspensory (diaphragmatic) ligament present, later atrophies.

Mesonephric (Wolffian) duct present.

Explain the level of Testicular Descent at 11 weeks

11 weeks (43 mm crown-rump)

Testes descend slightly, now closer to the deep inguinal ring.

Epididymis begins to form along testis.

Gubernaculum persists, guiding testis downward.

Urinary bladder descends relative to the gonads.

Explain the level of Testicular Descent at 4 lunar months

4 lunar months (107 mm crown-rump)

Testes approach the deep inguinal ring.

Epididymis more distinct.

Gubernaculum continues to shorten, pulling testes downward.

Testes preparing to enter the inguinal canal.

Explain the level of Testicular Descent at 8 lunar months

8 lunar months (26 cm crown-rump)

Testes have passed through the inguinal canal.

Located in the scrotal sac.

Superficial inguinal ring now behind them.

Ductus deferens visible.

Gubernaculum attaches testes to scrotal sac.

Compare level of Testicular Descent in an 8 lunar month fetus & a 1 month old infant

Cryptorchidism

absence of one or both testes from the scrotum.

(Most common birth defect of the male genital tract)

% incidence of cryptorchidism

3% of full-term and 30% of premature infant boys are born with at least one undescended testis. However, about 80% descend by the first year

True incidence of cryptorchidism around 1% overall.

How is development of male genitalia similar to the development of female genitalia

Hypospadias

A common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis.

2nd most common birth abnormality of the male reproductive system, affecting about one of every 250 males at birth.

Benign prostatic hyperplasia (BPH)

Prostate enlargement - noncancerous increase in size of the prostate gland

what does this diagram show

T1-3 stages of prostate cancer

(The most common cancer in males in 84 countries)

Scrotum contains the ________

Gonads

Sebaceous glands on the genitalia secrete what for what purpose

Sebaceous glands secrete an oily/waxy secretion called sebum. Sebum lubricates skin and hair, prevents water loss, and provides some antimicrobial defense.

Of the 3 erectile columns of tissue that the penis is made up of, which one has the swollen end - the glans penis

The ventral one - corpus spongiosum

The proximal end of the penis is attached to what membrane

Perineal membrane

(The perineal membrane is a tough, fibrous sheet that spans the urogenital triangle of the perineum. The root of the penis is anchored to it: Bulb of penis (corpus spongiosum) attaches in the midline of the perineal membrane. Crura (corpora cavernosa) attach laterally to the ischiopubic rami, with their medial parts anchored at the membrane. After that, the penile shaft extends forward (anteriorly) and is free of the membrane)

What is the roughening along the ischiopubic rami for

The roughening along the ischiopubic rami is where the ischiocavernosus muscle (a thin sheet of skeletal muscle) attaches. It runs from the ischiopubic ramus → to the crus of the penis (the proximal part of the corpus cavernosum).

Which penile erectile column contains the penile urethra

Corpus spongiosum

What lie inferior to the prostatic urethra

the urogenital diaphragm (deep perineal pouch)

Towards the end of the prostatic urethra, two tubes open into it. What are the 2 tubes?

the ejaculatory ducts, formed by the union of the ductus deferens and seminal vesicles

Surgery to lengthen penis

make a small incision into the penile suspensory ligament, it can lengthen the penis by a small bit

What is the effect of contraction of the dartos & cremaster muscle on the scrotum & when would they contract

Dartos muscle = smooth muscle: From thinking about entering cold water, skin around the scrotum with shrivel up - contraction of dartos muscle

If you stay in cold water - testes will move up towards the body - cremaster muscle

Blood supply to the gonads comes from where

Directly from the aorta - the testicular artery

Why are the testes located outside the abdominal cavity

temperature important in proper maturation of sex cells

intricate venous network around the testes =

pampiniform plexus

Role of bulbourethral glands

During sexual arousal / erection, they secrete a clear, mucus-like fluid into the spongy urethra.

Roles of this fluid:

• Lubrication → reduces friction during intercourse.

• Neutralizing acidity → helps flush out residual urine and neutralize acidic urine in the urethra, making a safer environment for sperm.

100s of seminiferous tubules combine to form what

Epididymis → a single, long, highly coiled tube where sperm mature and are stored

what is each part of this for (seminiferous tubule cross-section)

• Epithelial cells (green in your image)

  • These are the Sertoli cells, which are tall, columnar cells lining the tubule.

  • Function: Support and nourish developing sperm cells (spermatogenic cells) and help move them toward the lumen.

• Smooth muscle-like cells (yellow outer layer)

  • These are myoid cells, which are contractile cells surrounding the tubule.

  • Function: Perform peristaltic-like contractions to push sperm and fluid from the developing germ cells toward the lumen of the seminiferous tubule.

• Lumen (center of tubule, brownish area)

  • This is where mature sperm are released before entering the rete testis → efferent ductules → epididymis.

Importance of the blood-testes barrier

keeps new genetic information in sperm from the immune system in the body

Major disruption to this barrier can be very dangerous

What are the first cells that go through reduction division in the formation of sperm

primary spermatocytes

Role of the acrosome

Enzymatic - help sperm penetrate the egg

The epididymis is where sperm mature and gain motility but what else happens here

A lot of the fluid in which sperm are suspended is reabsorbed.

This resorption of water concentrates the sperm and allows them to mature properly.

What % of semen is sex cells

1%

After ejaculation, what happens the semen

First that happens ejaculation is the semen coagulates - sticky substance left in vagina for a while until enzymes liquify it so that sperm can move freely

Match:

Parasympathetic / Sympathetic

Erection / Ejaculation

Parasympathetic - Erection 

Sympathetic - Ejaculation

(Mnemonic: “Point and Shoot”)

The testes are pulled town into the pelvis by the what

gubernaculum (fibrous cord)

Most common form of hypospadias

Coronal

If you have hypospadias what are you more prone to

UTIs

Is prostate cancer or benign prostatic hyperplasia more common

Benign prostatic hyperplasia 

What does Benign prostatic hyperplasia present as

Difficulty urinating

A man being grumpy could be a sign of what

Prostate cancer - their testosterone is too high