Embryology Of Urinary System Flashcards
The first kidney to appear is……, opposite somites…….in……region, during……
The part of it that persists becomes………
Pronephros, 7-14, cervical, beginning of 4th wk
Mesonephric ducts
The 2nd kidney to appear is……., in …..region opposite……somites.
Mesonephros
Thoracic & upper lumbar
14-28
The number of tubules of mesonephric duct is……, its medial end forms………while opposite side forms….
70
Bowman’s capsule
Mesonephric or Wolffian duct
Mention components of urogenital fold
Mesonephric ridge or Wolffian body laterally
Genital ridge medially
The mesonephric tubules degenerate from….to….., and majority disappear by…….
Cranial to caudal
2nd month
Describe fate of mesonephric tubules in male
Upper: form superior aberrant ductule (join rete testis)
Middle (6-12 tubules) form the vasa efferentia & head of epididymis
Lower tubules form inferior aberrant ductule (open into duct of epididymis) + the paradidymis (does not open on duct of epididymis or rete testis)
Describe fate of mesonephric duct in male
It blind upper end forms appendix of epididymis
The rest will give:
1. Body & tail of epididymis
2. Vas deferens
3. Seminal vesicle
4. Ejaculatory duct
5. Caudal most part gives ureteric bud & trigone & back of prostatic urethra above ejaculatory ducts
Describe fate of mesonephric tubules & duct in female
T: upper will degenerate, middle form the epoophoron (above ovary), lower will form paroophoron (medial)
D: caudal most part forms ureteric bud & trigone the rest forms Gartner’s duct (lateral to uterus & vagina till hymen)
The third kidney is……appears during……in……..
Metanephros
5th week
Lower sacral & lumbar regions
Ureteric bud arises from……, cranial end forms……, the rest elongates forming…….
Dirsomedial aspect of mesonephric duct
Primitive renal pelvis
Ureter
Describe the divisions of the reanl pelvis
- 1st generation cranial & caudal forms major calyces later a middle one develops
- 2nd generation enlarges & absorbs the 3rd & 4th generations forming the minor calyces
- 5th generation forms ducts of Bellini
- 6-12 generation form collecting ducts
Collecting tubules of metanephric ducts become covered by……., one end forms…..& acquires…….while the other end forms……..
Metanephric tissue cap
Bowman’s capsule
Glomerulus of capillaries
Open connection with one of the collecting tubules
Mention the 4 changes that occur to the developing kidney
- Change in shape: lobulated appearance disappears during infancy
- Change in size: initially located in pelvis & ascend due to growth of body caudal to them
- Change in blood supply: in pelvis it recieves blood supply from median sacral as it ascends it recives from common iliac then aorta at successively higher levels, the lower vessels degenerate.
- Change in direction: hilum initially directed forward then rotates so it’s medial
Describe fate of excreted urine during intrauterine life
Metanephros becomes functional during 2nd half of pregnancy urine is mixed with amniotic fluid then swallowed where it enters intestinal tract then it is absorbed into bloodstream & enters the placenta to transfer metabolic wastes to the mother.
Describe cause & presentation of renal agenesis
Caused by early degeneration of ureteric bud when the ureteric bud fails to reach metanephric tissue the latter fails to proliferate
If bilateral, there is oligohydraminos, fetus is born alive since kidneys are not necessary before birth but dies within few days
If unilateral, may pass unnoticed till there are problems in the solitary kidney
Describe cause of congenital cystic kidney
It is due to failure of union between some collecting & excretory tubules thus the latter esp DCT, become distending with urine forming cysts. May be polycystic kidney or solitary cyst.
Describe cause of double kidney
Caused by early splitting of the ureteric bud on one side, the metanephric tissue becomes divided into 2 parts forming 2 kidney.
Describe cause of pelvic kidney
Failure of one kidney to ascend through the arterial fork formed by umbilical arteries
Describe cause & presentation of horseshoe kidney
Sometimes both kidneys are pushed so close duringvtheir passage in the arterial fork that their lower poles fuse resulting, they are located at lower level since root of inferior mesenteric art prevents its ascent. Ureters emerge from their ventral aspect as they fail to rotate
It is a common condition 1 in 600
Describe cause & presentation of aberrant renal artery
Caused by persistance of one or more of the transient vessels during shifting of arterial blood supply, can enter kidney through lower pole not hilum
May cause ureteric obstruction
Mention the forces controlling filtration & their normal values
F favoring filtration: hydrostatic glomerular capillary pressure (60 mmHg), colloid osmotic presssure in Bowman’s capsule (0)
F opposing filtration: colloid oncotic pressure of PP in capillaries (32 mmHg), intracapsular pressure (18 mmHg)
Mention equation of GFR
GFR=Kf*net filtartion pressure
Kf is glomerular capillary filtration coefficient
Mention factors affecting Kf its equation & it normal value
Permeability & surafce area of capillary bed
Kf=permeability of membrane*effective surface area
12.5
List factor affecting GFR
- Glomerular capillary pressure
- Colloid osmotic pressure of plasma protein (opposing)
- Intracapsular hydrostatic pressure (opposing, inc in ureteric obstruction)
- Functioning kidney mass
- Permeability of membrane (inc by hypoxia, fevers, some renal diseases)
- Filtering surface area (dec by contraction of mesangial cells & vice versa)
