Renal Embryo Flashcards
What do both the urinary and genital systems develop from?
Intermediate mesoderm
What do both the urinary and genital systems initially drain into?
A common cavity, the cloaca
What organs does the urinary system have?
Kidney, ureter, bladder, urethra
What do the kidneys ultimately end up as?
bilateral paired organs located in the lumbar retroperitoneum
What are the three overlapping kidney systems?
pronephros, mesonephros, metanephros (sequentially)
Where does the pronephros develop? Is it functional?
Cervical region; nonfunctional and rudimentary, comes and goes away in 4th week
As the pronephros involutes, what is formed? Where?
Mesonephros and mesonephric duct (Wolffian Duct). Upper thoracic to upper lumbar region
What is each tubule of the mesonephric duct supplied by, and what does it end in?
Each tubule supplied by fetal aortae which ends in a “glomerulus” (primitive). Minimal
filtration, and there is drainage through the Wolffian duct into developing cloaca
The mesonephric duct and a few tubules persist in ________, but disappear in ______
the male as part of the genital system; the female
When does the metanephros and definitive kidney appear?
5th week
What does the excretory system develop from? What’s it induced by?
Metanephric mesoderm; induced by developing tubules; urine production is at 10 weeks
What does the duct/collecting system (ureter, pelvis, calyces) develop from?
Uteric bud (@ distal mesonephric duct)
What is kidney development regulated by?
Epithelial-mesenchymal interaction! Mesenchyme initially expresses WT1, which goes on to
regulate other molecular players
What are the minor calyces formed from? How is the renal pyramid formed?
2nd order tubules enlarge to absorb the 3rd and 4th generations and form minor calyces; 5th+
generations elongate and drain into the minor calyces forming the renal period
What is congential polycystic kidney disease?
Cysts form from collecting ducts, resulting in renal failure in infancy (autosomal recessive). If it’s autosomal dominant, all segments of the nephron involved and delayed onset renal failure
What’s multicystic dysplastic kidney?
Numerous ducts surrounded by undifferentiated mesenchyme. No nephrons. May lead to
involution and renal agenesis
What’s Potter sequence?
Renal agenesis or severe malformation à anuria, oligohydramnios, pulmonary hypoplasia,
GU anomalies
Briefly discuss Wilm’s Tumor (Nephroblastoma)
Pediatric tumor of the kidney that results from mutations in WT1 or WT2. Can be associated
with other anomalies. Survival ~ 90% after surgery, chemo, radiation
Regarding the renal arteries, _____ branches usually disappear as more _____ branches are
created
inferior; superior
The kidney will ascend and rotate to assume its position with the calyces and the arteries
medial. True or false
True; there are actually a wide range of anomalies of fusion, ascent, or rotation i.e.
‘horseshoe’ kidney, crossed ectopia of kidney, pelvic kidney
What is the bladder and urethra derived from?
Cloaca
What divides the cloaca into the anal canal and the UG sinus in the 4th-7th week?
urorectal septum
What origin is the seminal vesicle?
Wolffian Duct (mesonephric duct)
How is the trigone of the bladder formed?
Mesonephric duct gets absorbed into posterior bladder to form the trigone. Ureter rises
cranially as kidneys ascend. Trigone lining initially mesodermal in origin and then become replaced by endodermal lining à in cancers, not surprising that different things can happen in
the trigone of the bladder compared to the rest of the bladder
What is the bladder formed by?
Upper part of UG sinus
Bladder is in continuity with the _____. This structure obliterates to become a thick cord
urachus (________)
allantois; median umbilical ligament
Where would you feel a urachal cyst in a baby?
Midline below the umbilicus
What is the lower, narrow part of the UG sinus?
Urethra
