Module 6: Development of the Urinary and Genital Systems Flashcards
What does the urinary system consist of?
kidneys, bladders, ureters, and urethra
What is the urinary system responsible for?
production and elimination of urine
What does the genital system consist of?
external genitalia, internal organs, gamete/hormone producing gonads
What is the genital system responsible for?
reproductive activity, sexual satisfaction, hormone production
What are the 3 mesoderm divisions?
paraxial, intermediate, lateral
What does the paraxial mesoderm form?
muscle, CT, and somites
What does the intermediate mesoderm form?
kidneys and genitals
What does the lateral mesoderm form?
pharyngeal arches and limbs
When the development of the urinary and genital systems start?
around week 4
What are the urogenital ridges?
parallel ridges on either side of the midline of the embryo made out of intermediate mesoderm
What are the urogenital ridges divided into?
genital and nephrogenic ridges
What will the genital ridge develop into?
the genital system
What will the nephrogenic ridge develop into?
urinary tract
What type of cell does the kidney contain?
nephrons
What makes up the excretory portion of the kidney?
glomerulus, proximal convoluted tubule, loop of henle, distal convoluted tubule
What makes up the collecting portion of the kidney?
collecting ducts and tubules (minor and major calyces), renal pelvis, ureter
What 3 systems form within the nephrogenic ridge?
pronephros, mesonephros, metanephros
What is the pronephros?
- first and most cranial kidney system
- develops in the cervical region during the 4th week and regresses by the end of the week
- vesicles formed by intermediate mesoderm link together to form the pronephric duct
Where does the nephrogenic ridge start to appear?
opposite the cervical segments of the embryo
What does the pronephric duct open into?
caudal tip opens into the cloaca
During regression of the pronephros, what regresses and what remains?
pronephric part of the nephrogenic ridge and pronephric duct -> regresses, remainder is the mesonephric duct
What is the mesonephros?
- formed during the regression of the pronephros
- develops in the thoracic and lumbar regions
- functions as the primitive kidneys and urinary system for week 4-12
- regresses in females
- forms several structures of the male genital system
What are the 2 components of the mesonephros?
mesonephric tubules and mesonephric duct
What are the mesonephric tubules?
associated with the glomeruli and drain into the mesonephric duct
What do the lateral ends of the mesonephric tubules do?
fuse and open into the duct
What do the medial ends of the mesonephric tubules do?
associate with blood vessels by lengthening toward and around the glomeruli
What is the mesonephric duct?
attaches to the cloaca and forms a primitive excretion pattern
What is the metanephros?
- will eventually become the adult kidney
- appears during the 5th week in the lumbosacral region
- replaces the primitive urinary system of the mesonephros
What is the ureteric bud?
- epithelial outgrowth of the mesonephric duct
- grows into the metanephric tissue to form the metanephric system
What are the 2 components of the metanephric system?
the collecting and excretory systems
When does the metanephros system begin functioning?
week 12
When does the collecting system start developing?
week 6
What are the steps to collecting system development?
penetration - ureteric bud penetrates the metanephric tissue and dilates to form the primitive renal pelvis and major calyces
division - major calyx forms 2 new buds that subdivide until 12 generations of tubules have developed
formation - gens 2-4 form the minor calyces, gens 5-12 form the renal pyramids and the collecting tubules
What is a nephric vesicle?
induced to form the metanephric tissue on the tip of each collecting tubule; develop into the nephric tubules
What are nephrons made up of?
nephric tubules and glomeruli
How do the kidneys ascend?
- initially they lie close to each other on opposite sides of the sacral segments
- start to ascend to the posterior abdominal wall during week 6-9 and medially rotate so that hiluses face medially
What are the 3 portions of the urogenital sinus
urinary bladder, urethral portion, phallic portion
What does the urethral portion gives rise to?
the prostatic urethra in males and urethra in females
What does the phallic portion gives rise to ?
the clitoris and penis
What do the mesonephric ducts give rise to?
the ureters and the ejaculatory duct in males
What are the gonads responsible for?
producing gametes and sex hormones