Development Of Urogenital System Flashcards
What part of the trilaminar disc do the urogenital structures and adrenal cortex arise from?
Intermediate mesoderm
3 stages of kidney development
What direction are these stages going?
Pronephros, mesonephros, and metanephros
Cranial to caudal
Difference in structure of the mesoderm in the following systems:
- Pronephric system
- Mesonephric system
- Metanephric system
- Segmented intermediate mesoderm
- Unsegmented intermediate mesoderm
- Unsegmented mesoderm
Solid, unsegmented mass of tissue formed in the lower thoracic, lumbar and sacral regions is called?
Nephrogenic cord
Pronephros:
- Location
- When does it disappear in mammals?
- Cervical region (group of 7-10 solid cell groups)
2. At 4 weeks
Mesonephros:
- Mesonephros and mesonephric ducts are derived from intermediate mesoderm from __ to __
- Function? When does it become functional
- Which duct persists in males?
- What happens during regression of the pronephric system?
- Upper thoracic to upper lumbar (L3) segments
- Remove wastes - functional during month 2
- Wolffian ducts
- The first excretory tubules of the mesonephros appear
Mesonephros- Excretory tubules: 1. They lengthen and acquire \_\_; this will form? 2. Next the tubules form \_\_, where? 3. Laterally, the tubule enters \_\_
- Tuft of capillaries that form glomerulus at their medial extremity
- Bowmans capsule around the glomerulus
- Longitudinal collecting duct aka Wolffian duct
Mesonephros:
- Next, during the second month, the mesonephros forms __
- Where is this in relation to the developing gonad?
- Ridge formed by both of these organs is called?
- Large ovoid organ on each side of midline (will be kidneys)
- Gonad is on medial side of developing kidneys
- Urogenital ridge
Mesonephros:
End of second month:
Caudal tubules are still differentiating; what is happening to cranial tubules/glomeruli
They have shown degenerative changes, majority disappear by end of 2nd month
Mesonephros:
- What happens to the caudal tubules/mesonephric duct in males?
- Females?
- They participate in formation of the genital system
2. They disappear
METANEPHROS:
- Kidney is now able to perform what function
- Where do its excretory units develop from?
- Excretory unit branches off mesonephric duct as?
- Concentrate urine to conserve water
- Metanephric mesoderm (in same manner as mesonephric system)
- Ureteric bud
Kidney develops from what 2 sources and what do each provide?
Metanephric mesoderm- provides excretory units
Ureteric bud- gives rise to the collecting system
Duct system formation:
- Ureteric bud invades__ to induce it to differentiate into the nephron
- Ureteric bud branches repeatedly to form__
- Ureteric bud penetrates __ to form primitive renal pelvis
- Cranial and caudal portions of renal pelvis become?
- Metanephric blastema (mesenchyme)
- Collecting portions
- Metanephric tissue
- Major calyxes
So ureteric bud gives rise to what 4 things?
Ureter, renal pelvis, major/minor calyces and ~1-3 million collecting tubules
As embryo grows, metanephric kidney relocates from __ to __ (vertebral levels)
What happens during this relocation
From S2 to T12
The blood supply branches from successively more cranial portions of the aorta
- Mesenchyme expresses WT1 which regulates production of which two genes? Function?
- What are the receptors for these 2 genes? What kind of receptors are they?
- What do these receptors do?
- GDNF and HGF; stimulate branching and growth of the ureteric buds
- RET is receptor for GDNF, MET is receptor for HGF; these are tyrosine kinase receptors
- Establish signals between the epithelium of ureteric buds
- Which 2 growth factors stimulate proliferation of mesenchyme/block apoptosis?
- Other function of these 2 growth factors?
- FGF2 and BMP7
2. Maintain WT1 expression
Function of WT1?
Enables tissue to respond to induction by ureteric bud
- Ureteric buds convert mesenchyme to an epithelium for __ formation
- This is mediated by expressing what 2 genes?
- These 2 genes up-regulate what 2 genes?
- Nephron
- WNT93 and WNT6
- PAXZ and WNT4 (in the metanephric mesenchyme)
- PAXZ promotes condensation of mesenchyme to prepare for?
2. WNT4 causes the condensed mensenchyme to __ and form __
- Tubule formation
2. Epithelialize and form tubules
ECM modifications also occur during kidney development:
- Fibronectin, collagen types I and III are replaced with what 2 things that are characteristic of an epithelial basal lamina
- What two molecules are essential for condensation of the mesenchyme into epithelium?
- Laminin and collagen type IV
2. E-cadherins and syndecan
Cloaca divides into __ anteriorly and __ posteriorly
Cloaca is divided by what?
Urogenital sinus anteriorly and anorectal canal posteriorly
Urorectal septum
Urogenital sinus develops what 2 portions? These lead into the
Urethral and bladder portion; allantois
Allantois regresses to form __; what does this connect?
How is this seen in adults?
Urachus; connects apex of the bladder with the umbilicus
Seen in median umbilical fold of adult
What happens to the phallic part of the urogenital sinus as the genital tubercle grows?
It gets pulled ventrally
- How does the caudal portions of the mesonephric duct enter the bladder; what does it become
- How do the ureters enter the bladder
- They are absorbed into the wall of the urinary bladder during differentiation of the cloaca; becomes the trigone of bladder
- Ureters are initially outgrowths from the mesonephric ducts, enter the bladder separately