Embryology - Urinary system development Flashcards
What do the urinary and genital components of the urogenital system develop from?
Both develop from a common mesodermal ridge (Intermediate mesoderm)
What are the three kidney systems that develop?
- Pronephros (rudimentary, nonfunctional)
- Mesonephros (function for a short time during early fetal period)
- Metanephros (Forms the permanent kidney)
In what direction does the 3 kidney system develop?
Cranial to caudal
Describe the Pronephros….
- Appears at day 21
- In segmented intermediate in the cervical region
- Degenerates by day 24.
Never functional in humans.
Describe the Mesonephros…
- Appears early week 4
- Thoracic & lumbar segments of intermediate mesoderm.
- Urine is produced and drains along the mesonephric (Wolffian) duct to the cloaca/bladder.
- In week 5 the thoracic segments regress but the mesonephric kidney continues functioning until week 10.
Tell me about the Mesonephric/Nephrogenic duct….
Many mesonephric vesicles that develop craniocaudally—-> Tubles ( around 40 total) —> primordial nephron.
*Functional 6-10 weeks
Mesonephric ducts extend into the lower lumbar and fuse with _______ contribute to _________.
Cloaca
Posterior Bladder
________ initiates the Urerteric bud/Metanephric Diverticulum growth.
Mesonephros
What are the 2 components of the Metanephros?
- Collecting portion (Ureteric bud, day 28)
2. Excretory portion (Metanephric blastema)
Where does the Metanephros orginate?
At the metanephric diverticulum. (ureteric buds) sprout from the distal end of the mesonephric duct at week 5.
When does the ascent of the kidneys take place?
6-9 weeks
What causes the kidneys to ascend?
Growth in length
How does the formation of the bladder begin?
Cloaca in the handgun becomes divided by urorectal septum —-> ventral urogential sinus and a dorsal anorectal canal
What is the trigone of the bladder?
The distal Portion of the mesonephric duct and the attached ureteric ducts, become incorporated into the posterior aspect of the bladder.
