Histological differences and similarities between the male and female urethra.

The urethra is the unpaired excretory passage that conducts urine from the bladder to the exterior of the body, even though in the male, the urethra is shared with the reproductive system. The urethra is longer in males than in the females but they share some histological similarities.

• In the male urethra, the muscular layer is only well defined in the non-membranous and prostatic parts while in the female urethra, the muscular layer is very well defined.

• In the males, the pelvic urethra is surrounded by occasional fibres while in the female urethra, it is totally absent.

• The male urethra is shared with the reproductive system while the female urethra is exclusively made for the urinary system.

• The male urethra is very complex while the female urethra is simple.

• The male urethra is quite long (about 18-20cm) while the female urethra is very short (about 4cm).

• In the flaccid state, the male urethra has an S-shape and in the erect state, it is J-shaped but the cross-section of the female urethra is crescentric in shape at the upper part, stallate in the middle part and transverse in the lower part.

• In the mal urethra, there is presence of a prostate gland while the female urethra has no prostate gland.

• There is presence of Para-urethral gland of skene in the female urethra while the male urethra ha no Para-urethral gland of skene.

• The male urethra cannot dilate while the female urethra can easily dilate for cathetures to pass through.

1. Both the male and the female urethra have a mucous layer in their wall with the following characteristics:

• It I lined by lining epithelium or stratified squamous non-keratinized epithelium.
• The epithelium rests on a connective tissue.
• The outer part of the urethra is lined by pseudo stratified columnar epithelium.
• The short part adjoining the urinary bladder is lined by transitional epithelium.
• The part near the external urethral orifice is lined by stratified squamous epithelium that is non-keratinized.
• The mucosa shows invaginations or recesses into which mucous glands open.

2. Both the male and female urethra have sub mucous layer in their wall with the
following characteristics:

• It consists of loose connective tissue.
• There is presence of thick fibro elastic lamina propria.
• The lamina propria contains plexus of thin walled veins.

3. Both the male and female urethra have a muscular layer with the following
histological characteristics:

• The smooth muscle of the membranous part of the male and the corresponding part of the female urethra are surrounded by stratified muscles that forms the external urethral sphincter.
• It has an inner longitudinal muscular layer and an outer circular muscular layer.