The rest of the urinary system In this lecture, we will consider; 1.Ureters 2.Bladder 3.Urethra 4.Congenital abnormalities of the whole system
Urinary (=transitional) epithelium The Ureters:
Development of the bladder
Formation of the Trigone;
From Atlas of Human Anatomy (Netter)
Development of the prostate
Sex-specific development of nephric and Mullerian ducts. MALE Indifferent gonad develops testis cords Testis cords connect to some mesonephric tubules (->epidydymis) Mullerian duct regresses Distal neprhic duct sprouts seminal vesicles – the part of the nephric duct distal to this is the ejaculatory duct Urethra sprouts prostate and bulbourethral glands. FEMALE Indifferent gonad develops into an ovary Upper Mullerian ducts become fallopian tubes Mullerian ducts converge & fuse to become the uterovaginal canal Neprhic ducts and mesoneprhos degenerates Uterovaginal canal forms uterus and upper part of vagina. (Lower part from urogenital sinus)
From Atlas of Human Anatomy (Netter)
Components of semen Testis – sperm Prostate – citric acid, enzymes, acidic proteins Sem. Ves. – fructose, basic proteins
Timing of release Prostate Epididymis Sem. Ves
The opening to the world His: Urethra runs along penis and opens at its end Hers: Urethra ends within vulva and does not run to end of clitoris.
Size isn’t everything, but… Differential growth of the initially identically-sized male and female phallus results in the following differences in length; Females: 16 +/- 4mm (erect) Males: /- 27mm (flaccid) 162 +/-32mm (erect) (A difference of about 10:1)
Derivatives of the cloacal region – his & hers Genital tubercle – Glans and shaft of penis (male) (Phallus) Glans and shaft of clitoris (female) Urogenital Sinus – Penile urethra (male) Lower vagina (vestibule) (female) Urethral fold - Surrounds urethra of penis (male) Labia minora (female) Labioscrotal fold- Scrotum (male) Labia Majora (female)
Congenital Abnormalities We’ll consider the kidney first, then the bladder, then the external genitalia
Renal Agenesis Bilateral – No kidneys form. Rare; fatal after birth. Lack of amniotic fluid causes Potter’s Facies. Unilateral – One kidney missing. Common (1/500). Often no clinical implications unless some bright surgeon removes the working one (yes, it has happened!).
Congenital Cystic Disease Various types; together they keep paediatric nephrologists busy. Seem to result from mutations that either make the collecting duct cells grow too much or to become confused about which side of the epithelium is ‘in’ and which ‘out’ so they pump the wrong way.
Wilms Tumour Islands of kidney tissue remain in a foetal state when kidney development ought to have ceased (‘nephrogenic rests’) and some then begin to grow as a tumour, mimicking some aspects of normal development.
Other abnormalities Supernumerary ureters (cause trouble when one opens somewhere other than the trigone of the bladder – eg the vagina). Pelvic kidneys )kidney fail to ascend, perhaps because they are caught in the aortic bifurcation Horseshoe kidneys – the kidneys fuse (pelic kidneys particularly prone to this).
Congenital Abnormalities of Cloacal Development Failure of correct positioning of Rathke and Tourneaux folds results in; Rectovaginal fistula Rectoprostatic fistula Rectoclocal canal (rectum, vagina and urethra unite inside body). In males, incomplete migration of the urethral groove from the base of the penis to its tip results in hypospadias.