9. Embryology Flashcards
What is the general characteristics of the formation fo he 3 separate kidney system?
Organisation of intermediate mesoderm
3 systems develop sequentially
Disappearance of one system marks the onset of development of the next developmental stage
1st appears in cervical region
What are the 3 systems of the kidney formation?
Pronephros
Mesonephros
Metanephros
What is the first step in kidney embryology?
The pronephros
- first kidney system (never functions in humans)
- is a duct, extends from the cervical region to the cloaca and drives the development of the next developmental stage
What is the urogenital ridge?
Region of intermediate mesoderm giving rise to both the embryonic kidney and the gonad
What is step 2 of kidney embryology?
Mesonephric tubules develop caudal to pronephros region
Mesonephric tubules and mesonephric duct form the embryonic kidney
No water conserving function
What does the mesonephric duct sprout?
Ureteric bud which induces development of the definitive kidney
What is the ureteric bud?
Undifferentiated intermediate mesoderm, caudal to the mesonephros
Ureteric bud induces development of the true kidney, metanephros in this tissue
Describe how the ureteric bud becomes the renal pelvis
Ureteric bud contacts metanephric blastema
Bud expands and branches
Forms renal pelvis, major calyx and minor calyx
What is the collecting system derived from?
Ureteric bud
What is the excretory component derived from?
Intermediate mesoderm under the influence of the ureteric bud
Describe the ascent of the kidney
Metanephric kidney first appears in pelvic region
Undergoes an apparent caudal to cranial shift, crossing the arterial fork formed by vessels returning blood from the fetus to the placenta
What is renal agenesis?
Ureteric bud fails to interact with intermediate mesoderm
Bilateral is incompatible with life
What are the 2 major structural anomalies related to migration?
Pelvic kidney
Horseshoe kidney
What happens in duplication defects and ectopic urethral orifices?
Splitting of ureteric bud
Partial or complete
Symptomatic consequence is ectopic ureteral opening (vagina, bladder, urethra)
What is the urogenital sinus?
Created from hindgut by urogenital septum
Continues with umbilicus via urachus which closes to become median umbilical ligament
Majority differentiates to form urinary bladder
Inferior part develops into urethra
