Urogenital System Flashcards
2 parts of the urogenital system
urinary and genital systems
what does the urogenital system develop from
the intermediate mesoderm which forms a longitudinal urogenital ridge
Urinary system constituents
kidneys, ureters, bladder, urethra, nephrons
Kidneys
produce urine
Ureters
Convey urine from the kidneys to the bladder
bladder
stores urine
Urethra
excrete urine from the bladder
Nephrons
functional units of the kidney
Pronephroi
- rudimentary and non-functional
- appear in early week 4 as sedmentally arranged cell and tubular structures in the cervical region of the mesoderm
- Ducts run caudally and open into the cloaca
Mesonephroi
- Function for a short time
- Appear in late week 4
- Arise from cell clusters which form vesicles then tubules
- Tubules contact pronephric duct which now becomes the mesonephric duc
- Degenerate at the end of the first trimester, tubules become the efferent ductules of the testes
Mesonephrc Kidneys
Consist of glomeruli and tubules. Mesonephric tubules open into bilateral mesonephric ducts which open into the cloaca.
Metanephroi
- Permanent kidneys
- Develop week 5, function week 10
- produce urine and excretes it into the amniotic fluid, fetus drinks amniotic fluid ad wastes are absorbed and released via. the placenta
What do the metanephroi develop from
metanephric diverticulum and metanephric blastema
Metanephric diverticulum
begins as an outgrowth from the mesonephric duct near the cloaca
- gives rise to the ureter (stalk), renal pelvis, major and minor callices, collecting ducts and tubules (cranial portion)
Metanephric blastema
- located in the caudal part of the nephrogenic cord
- as collecting tubules form, they induce the mesoderm to form clusters, vesicles, tubules, nephrons
First generation tubules (nephroi)
four tubules, become confluent and form major callices
Second generation tubules (nephroi)
Coalesce and form minor calices
what invaginates the proximal ends of metanephric tubules
glomeruli
Reciprocal inductive influence
When differentiation of both primordia depends on inductive signals from the other
- ex. metanephric diverticulum and mesoderm have reciprocal inductive influence
Examples of reciprocal induction
- Branching of the metanephric dverticulum is dependent on induction by the metanephric mesenchyme
- Differentiation of the nephrons depends on induction by the collecting tubules
- Metanephric diverticulum and the netanephrogenic blastem interact and induce eachother to form the permanent kidneys
Formation of uriniferous tubules
Metanephric tubules become continuous with the collecting tubules and for uriniferous tubules
Uriniferous tubules constituents
Consists of two embryologically different parts
- a nephron derived from the metanephrogenic blastema
- a collecting tubule derived from the metanephric diverticulum
How common are variations in arterial supply to kidneys
25%
When do definitive renal arteries appear
Week 9