- The kidneys develop from metanephros.
- The bladder and urethra develop from the urogenital sinus
- The prostate develops from an outgrowth of the urethral epithelium
- Preprostatic part – this is 1cm long and extends from the bladder to the prostate. It is associated with a ‘cuff’ of circular muscle fibres – the internal urethral sphincter. This sphincter closes during ejaculation, and this prevents movement of semen into the bladder during ejaculation.
- Prostatic part – this is 3-4cm long and is surrounded by the prostate. In this region, the urethra is marked by a longitudinal fold along the midline known as the urethral crest. The depression on each side of this crest is called the urethral sinus and it is here that the prostate empties its secretion. Halfway along the prostate is a small blind opening called the prostatic utricle – and it is thought that this is the equivalent of the uterus in men. Just below the prostatic utricle there are 2 openings that are the openings of the ejaculatory ducts. So, the connection of the reproductive and urinary tracts occurs in the prostatic urethra in men.
- Membranous part – this is narrow and it passes through the deep perineal pouch. During transit through the deep perineal pouch, in both men and women, the urethra is surrounded by skeletal muscle which forms the external urethral sphincter.
- Spongy urethra – this is inside the corpus spongiosum of the penis. At the base of the penis it is enlarged to form a bulb, and it does so again, this time at the other end of the penis to form the navicular fossa.
- These lie retroperitoneally at the level of L1-L2
- Usually, they are supplied by a single artery, but in some people there are multiple arteries.
- The renal vein drains the kidney into the inferior vena cava.
- Renal lymphatics drain into the para-aortic nodes.
Male Reproductive system
- These originally develop high on the posterior abdominal wall, and then descend (normally before birth) down through the inguinal canal, and into the anterior abdominal cavity and finally into the scrotum. During their descent, the testes carry with them their blood and lymphatic supplies, as well as the vas deferens.
- Therefore, the lymphatic drainage of the testes is to para-aortic nodes and not to inguinal or pelvic lymph nodes.
- The testes are ellipsoid in shape. Each testicle is enclosed in a fibrous pouch that is continuous with the anterior abdominal wall. The spermatic cord is the fibrous material that connects the covering of the testes with the anterior abdominal wall.
- The sides and anterior aspect of each testicle is covered by a peritoneal sac called the tunica vaginalis. During development, this sac was continuous with the abdominal cavity, but this closes off, leaving a fibrous remnant at the top of the testicle.
- Each testicle is composed of seminiferous tubules that are surrounded by connective tissue called the tunica albuginea. The seminiferous tubules are the site of sperm production.
- At the end of the seminiferous tubules is a section of tube known as the straight tubule. This connects to a collecting chamber known as the rete testis. Then, efferent tubules (about 12-20 of these), link the rete testis to the epididymis, where the sperm mature.
- The epididymis is a single, long, coiled duct that runs along the posterolateral side of the testicle. The epididymis can be divided into the head of epididymis, and the true epididymis. The true epididymis itself can be divided into a body and a tail.
- The end of the epididymis is continuous with the vas deferens.
- Sperm are stored in the epididymis until ejaculation
Ductus deferens (vas deferens)
- This is a long muscular tube the transports sperm from the epididymis to the ejaculatory ducts in the pelvis. It ascends from the scrotum as part of the spermatic cord, and passes through the inguinal canal.
- After this is turn medially and crosses the external and internal iliac veins at the pelvic inlet, to enter the pelvic cavity
- It descends medially along the pelvic wall, and crosses over the ureter just where the ureter empties into the bladder. It then carries on along the base of the bladder, almost at the midline, before it is finally joined by the duct of the seminal vesicle, to form the ejaculatory duct.