Reproductive Embryology Flashcards
What do the reproductive and urinary systems develop from?
mesoderm just lateral to the somites called intermediate mesoderm.
How do the mesonephric ducts form?
They form cranially to caudally and then fuse with the developing bladder
Where does the pronephros (first kidney) develop?
it develops in the cervical region and regresses (never functions)
Where does the mesonephros (middle kidney) develop?
in the thoracic to lumbar region (functions)
Where does the metanephros (third and definitive kideny) develop?
The mesonephric duct.
What are the the two parts of the metanephros?
The excretory system and the collecting system.
Where does the collecting system develop?
From the ureteric bud that sprouts from the mesonephric duct.
Where does the excretory system develop from?
Intermediate mesoderm cells that surround the ureteric bud, froming the metanephric blastema or metanephric mesenchyme.
What does the collecting system consist of?
The ureter, renal pelvic, calyces and 1-3 million collecting ducts.
What does the excretory system consist of?
nephrons, the functional unit of the kidney
What are nephrons?
They are vesicles or tubules that produce urine in the process of removing waste and excess substances from the blood.
What are glomeruli (capillary tufts)?
Capillaries that grow into the distal end of each nephron
How do kidneys shift due to the growth of the body?
cranially
What is a kidney that doesn’t completely ascend
pelvic kidney
what is a horeshoe kidney?
the fused kidneys ascend until caught under the IMA
What is bifed ureter or a double ureter?
the ureteric bud bifurcates before the metanephric blastema forms.
What is an ectopic kidney?
The kidney crosses to the other side during ascension
What is a thoracic kidney?
when the kidney ascends too far
What can congenital anomalies of the urinary system lead to?
urinary blockage, infection or kidney stones
What is multiple renal arteries?
The kidney is supplied by several arteries off the aorta during ascension, usually they degenerate. If these accesory renal arteries are damaged or ligated, part of the kidney can becomes ischemic.
When are the kidneys functional by?
The 12th week
How is fluid recycled through the kidneys?
urine is passed into amniotic cavity and mixes with amniotic fluid, fluid is swallowed by the fetus and recycles through the kidneys
What does bilateral renal agenesis result in?
oligohydraminos or insufficient amniotic fluid, causing compression of the fetus by the uterus.
What is potters sequence?
it results from oligohydraminos and results in limb deformities, wrinkly, dry skin; fascial anomalies (wide set eyes with infra-obrital skin creases, beak nose, recessed chin and low set ears); and pulmonary hypoplasia.
Where does the urinary bladder form from?
The caudal end of the hindgut (called the cloaca) when the urorectal septum (mesoderm) divides it into the urogenital sinus and the anorectal canal.
What does the urogenital sinus become?
The bladder and urethra
What does the allantois connect?
The apex of the bladder with the umbilicus.
What does the allantois become?
A fibrous cord called the urachus.
What is the urachus covered by and what does it become?
It is covered by peritoenum and becomes the median umbilical ligament on posterior aspect of the anterior abdominal wall.
What abnormalities can occur if the urorectal septum does not form correctly?
imperforate anus, urorectal fistula (an abnormal connect between the rectum and the bladder or the rectum and the urethra), and anal or anorectal agenesis.
What can persistence of a lumen in the urachus cause?
urachal fistula (urine can come out of the umbilicus), a urachal cyst, or a urachal sinus.
What does the reproductive system develop with?
The urinary system
What do primordial germ cells originate from? Where do they migrate and form?
They are originally from the epiblast, they migrate from the yolk sac into the intermediate mesoderm medial to the mesonephros causing formation of the gonadal ridge.
What does the epithelium covering the gonadal ridge do?
it is mesodermal in origin and it invades the underlying mesoderm to form the primitive or primary sex cords that surround the germ cells