development of the kidney and urinary tract Flashcards

1
Q

what are the three overlapping kidney systems

A

o Pronephros - cervical region, Non-functioning, rudimentary, develops in week 4 and disappears by week 5
o Mesonephros- thoracic and lumbar, may function for short period, develops in week 4 and has a duct connecting it to the cloaca in males it persists into adulthood.
o Metanephros- Permanent kidney, develops in the pelvis.

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2
Q

Mesonephros

A

• Mesonephric duct is lateral to the Mesonephric ridge.
- will form the Vas deferens in the male
• Glomeruli form and the filtrate passes into a tubule which ends by draining into the mesonephric duct (Wolffian duct).
• The mesonephric ducts end in the cloaca -The bladder forms from the cloaca
• Cranial tubules start to degenerate whilst caudal tubules are still forming
• By week eight all but the most caudal tubules have disappeared
• In the male these few caudal tubules form the efferent ducts of the testis
• In the female all tubules disappear

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3
Q

Metanephros

A
  • A ureteric tube buds off the distal end of the mesonephric duct
  • The tube grows into metanephric blastema - forms the glomeruli and tubules of the kidney
  • The ureteric tube forms the collecting ducts and ureter
  • Once the ureteric bud enters the blastema it divides and dilates, forming the primitive renal pelvis. It repeatedly divides forming the major and minor calyces- collecting tubules grow from the minor calyces to form the renal pyramids
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4
Q

describe the development of the position of the kidney

A

The kidney develops in the pelvis but shifts to a more cranial position in the abdomen, this is achieved by a diminution of body curvature and growth of the lumbar and sacral regions

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5
Q

how does the metanephros start functioning

A

12th week - Urine is passed into the Amniotic cavity and mixes with the amniotic fluid. The fluid is swallowed by the fetus and recycles through the kidneys

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6
Q

describe the development of the bladder and urethra

A
  • Cloaca – a common passage for the bowel, urinary and genital tracts,
  • Allantois is formed as an anterior outgrowth of the Cloaca, it forms the bladder.
  • Between the 4th and 7th week the Cloaca is divided by a mesodermal septum; the Urorectal septum forming an anterior Urogenital Sinus and a posterior Anorectal Canal
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7
Q

what are the 3 parts of the urogenital sinus?

A

o Upper part: is the largest part and forms the urinary bladder
o Pelvic (middle)part : gives rise to the prostatic and membranous parts of urethra
o Phalic part: forms the penile urethra

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8
Q

describe the development of the ureters and ejaculatory ducts

A
  • The ureters, develop as an outgrowths from the Mesonephric ducts and drain into the urogenital sinus
  • During differentiation of the cloaca and formation of the bladder, the caudal portions of the Mesonephric ducts are absorbed into the wall of the urinary bladder. Consequently, the ureters and mesonephric ducts enter the bladder separately.
  • The openings of mesonephric ducts move close together to enter the Prostatic Urethra and in the male become the ejaculatory ducts.
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9
Q

describe the development of the prostate

A
  • At the end of the 3rd month, epithelium of the prostatic urethra (endodermal in origin) begins to proliferate and forms a number of outgrowths that penetrate the surrounding mesenchyme and form the glands of Prostate.
  • Prostatic connective tissue and smooth muscles are derived from the Mesoderm.
  • In female, the Urethral epithelium gives rise to the Urethral and Paraurethral glands
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