Embryology Of The Urogenital System Flashcards
The nephrogenic cord forms 3 primitive kidneys. What are these kidneys?
- pronephric system
- mesonephric system
- metanephric system
Describe the proneprhros.
- nonfunctional cervical nephrotomes
- transitory and regresses by week 5
Describe the formation and function if the mesonephros.
- during 4th week, a second primitive kidney develops (present and functional from weeks 6-10)
- functional glomeruli develop
- mesonephric tubules form
- mesonephric duct opens into cloaca
After week 10 the mesonephros degenerates and leaves what behind?
- will contribute to part of the male genital system (ductus deferens)
- some vestigial structures in the female
Which primitive kidney forms the anatomical kidney?
-metanephros
What are the steps of renogenesis?
- involves a process of reciprocal induction, which I’d RA dependent
- cranial-caudal patterning establishes a renogenic region within the intermediate mesoderm in the tail of the embryo
- the renogenic mesoderm is the metanephric blastema
- the metanephric blastema secrets growth factors that induce growth of the ureteric bud from the caudal portion of the mesonephric duct
- the ureteric bud proliferates and responds by secreting growth factors that stimulates proliferation and then differentiation of the metanephric blastema into glomeruli and kidney tubules
- perturbations in any aspect of these inductive events may cause inhibition of ureteric bud growth and renal hypoplasia or agenesis
- conversely, duplication of overproliferation of structures can also occur
What are the functions of the metanephros?
-blood plasma from glomerular capillaries begins to be filtered by 10th week
-urine is produced, but the primary function is not to clear waste but to supplement production of amniotic fluid
+oligohydramnios: insufficient amount of amniotic fluid caused by bilateral renal agenesis or urethral obstruction
What are accessory renal vessels?
- kidneys are. Formed. In pelvis but ascent to lumbar. Region with progressive revascularization from common iliac and aorta
- aberrant renal vessels enter the kidney independently from the primary renal vessels
These occur in 10% of individuals and 98% arise from abdominal aorta. Most enter renal pelvis and pose little problem
When would an accessory renal artery cause a problem?
- aberrant renal arteries that enter the upper or lower poles of the kidney may pose problems
- inferior may cause obstruction of the ureter and may cause an intermittent or continuous obstruction to urinary drainage from the renal pelvis
What can renal agenesis lead to?
Potter’s syndrome
-not enough amniotic fluid
What causes renal fusion? What does it cause?
- prevents normal rotation
- abnormal blood supply - usually from middle sacral or common iliac arteries
- ectopic kidney - may also be crossed with/without fusion
- horseshoe kidney
What is a horseshoe kidney?
- most common
- 90% fused at lower pole
- usually found inferior to inferior mesenteric artery
What is Wilms’ tumor?
- cancer of the kidney that affects children under the age of 5
- caused by a mutation in the WT1 gene
How does the bladder form?
- the cloaca is divided by the urorectal septum
- the dorsal portion develops into the rectum and anal canal
- the ventral portion develops into the bladder and urogenital sinus, which will give rise to the bladder and lower urogenital tracts (prostatic and penile urethral in males, urethra and lower vagina in females)
How is the pelvic urethra related to the bladder in terms of development?
- ureteric buds open into bladder wall, while the mesonephric ducts open more inferiorly into the pelvic urethra (ductus deferens doesn’t open into the bladder)
- triangular region of the incorporated mesonephric duct incorporated in the bladder wall forms the trigone
