Week 2.1 - Development of the urinary system (workbook, embryology) Flashcards
where does the kidney and ureter develop from?
both from intermediate mesoderm at the urogenital ridge
what is the sequence of events?
pronephros
mesonephros
metanephros
what is the function of the mesonephric duct?
very important role in the development of the duct system of the male reproductive tract
what does the mesonephric duct sprout?
the ureteric bud - the primoridum of the collecting system of the definitive kidney
when does the mesonephros appear and regress?
appear week 4, regress week 8
where does the excretory system develop from?
metanephric tissue cap
what is the narrowed lower segment of urogenital sinus’ derivative in male urethra?
pre-prostatic urethra, prostatic & urethra membranous urethra
what does the phallic portion (enclosed by urethral folds) become in male urethra?
spongy urethra
where does the kidney shift in position during its development?
from the pelvis to the abdomen
why do the kidneys shift from the pelvis to the abdomen?
because of migration and expansion of the caudal (tail) region of the foetus
what does migration of the caudal region of the foetus include?
- craino-caudal shift from L4-L1/T12
- lateral displacement (meeting up with the adrenal glands in the process)
- a 90 degrees rotation so the renal pelvis faces the midline
what is the bladder a derivative of?
the hindgut
what does it mean when the bladder is a derivative of the hindgut?
it is derived from the caudal portion of the primitive gut tube formed during embryonic folding in the fourth week of development
what does the caudal portion contain?
a dilated blind pouch called the cloaca
what is the cloaca separated from the outside by?
cloacal membrane - one of the 2 mesoderm (less regions present after gastrulation)
what is also involved in the development of the bladder?
the allantois
what is the allantois?
a superoventral diverticulum of the hundgut and extends into the umbilical cord
what does the lumen of the allantois become?
obliterated to become the urachus, which is the median umbilical ligament in adults
what happens to the cloaca?
becomes divided by the urorectal septum into the urogenital sinus and anorectal canal
what does the urogenital sinus and anorectal canal?
US: future bladder and urethra
AC: future rectum and anal canal
what is the urethra formed by?
narrowing of the lower urogenital sinus
how does the distal portion differ in development?
differs between male and female
when does the distal portion of the urethra develop?
as the external genitalia change from an indifferent starting point to the morphology dictated by the genotype of the embryo
in males, how is the distal urethra like?
elongated (become the spongy urethra)
how does the penis develop?
fusion of the urethral folds under the influence of male sex hormones
in females, what does the urethra open into?
the vestibule
why does the urethra open into the vestibule in females?
because the urethral folds do not fuse
how is the male urethra split?
into 4 parts: pre-prostatic urethra prostatic membranous spongy
