Flashcards in Embryology: Urinary Deck (16):
After gastrulation what are the 2 areas of the mesoderm that do not separate the ecto and endoderm?
The buccopharyngeal membrane cranially
The cloacal membrane caudally
What is the embryological derivative of the kidneys?
What are the 3 kidney systems that form?
1. Pronephros - makes a duct which the mesonephros can use (purely structural, never functional)
2. Mesonephros (has tubules and duct)
3. Metonephros - the permanent kidney
(disappearance of 1 system marks the onset of development of the next system)
What is the urogenital ridge?
A region of intermediate mesoderm that gives risk to the embryonic kidney and gonad
What is the function of the mesonephros?
The mesonephric duct sprouts the ureteric bud which indices development on the definitive kidney
The mesonephric duct has an important role in the development of the male repro system
What is the role of the ureteric bud?
The ureteric bud drives development of the definitive kidney
The collecting system is derived from the ureteric bud itself
Outline the ascent of the kidney
The metanephric kidney first appears in the pelvic region
It undergoes a caudal to cranial shift - partially upward movement, partially elongation of the abdomen
As it descends it sprouts new vessels off the abdo aorta and the old vessels regress
What defects occur if there is splitting of the ureteric bud?
There can be accessory ureters (generally dont cause a problem)
The problem occurs if one of the ureters drains into the wrong place eg into the vagina, this causes incontinence
What is the urogenital sinus?
It is created from the urorectal sinus (mesoderm that grows downwards to separate the GI and urinary tracts)
It is continuous with the umbilicus
Has 3 parts - large upper part forms the bladder, then has pelvic and phallic parts
What happens to the mesonephric ducts in males and females?
Both sexes: The mesonephric ducts reach the urogenital sinus and the ureteric bud sprouts from the mesonephric ducts. The uorgenital sinus expands due to smooth muscle appearing and the ureteric bud makes a separate opening into the urogenital sinus.
**Males: the mesonephric duct becomes the vas deferens
**Females: The mesonephric duct regresses
What happens to the genital folds in males and females?
In males the genital folds fuse (driven by androgens) to form the spongey urethra
There is no fusion in females and the urethra opens into the vestible
What is hypospadias?
Occurs in males
A defect in fusion of the urethral folds resulting in the urethra opening onto the ventral surface of the penis instead of the end of the glans
How does horseshoe kidney occur?
The kidneys fuse during development to form a large horseshoe shaped kidney
What happens to the urachus?
The urachus usually regresses in the 12th week leaving behind a fibrous chord called the median umbilical ligament
What is a patent urachus?
The urachus fails to close off therefore there is a connection between the bladder and the umbilicus - there is leakage of urine out the umbilicus