Exam 2 - Lecture 30 (Urogenital System) Flashcards
What is a patent ductus arteriosus?
What happens if the DA doesn’t shut down properly
What is aortic coarctation?
Constriction of aorta
How do vascular ring anomalies happen?
If aortic arches do not degenerate properly
What are the 2 types of vascular ring anomalies that can occur?
- R 4th aortic arch –> adult aortic arch + R 6th aortic arch –> ductus arteriosus
- R 4th aortic arch –> adult aortic arch + L 6th aortic arch –> ductus arteriosus
Which vascular ring anomaly results in a normal animal with situs inversus?
R 4th arch –> adult aortic arch
R 6th arch –> ductus arteriosus
What happens in the vascular ring anomaly that results in an abnormal animal? At what point in the animal’s life does this begin to cause problems?
Ductus arteriosus degenerates into the ligamentum arteriosum which forms a ring around the esophagus and trachea;
Causes problems when the animal is weaned bc liquid diet can pass thru the ring but solids cannot
What are the 3 attempts of the body to make a kidney? Which one becomes the adult kidney?
- Pronephros
- Mesonephros
- Metanephros (becomes adult)
What two attempts of kidney formation are still retained in the adult kidney?
Pronephros and mesonephros
What two structures give rise to the urogenital ridge?
- Intermediate mesoderm
2. Coelomic mesothelium
Where are the urogenital ridges found?
Dorsal part of the embryologic coelom
Which is the most cranial, intermediate, and most caudal attempt at kidney formation?
Most cranial = pronephros
Intermediate = mesonephros
Most caudal = metanephros
What structures is the pronephros ventral to?
cervical somites
At what body level is the pronephric kidney developing?
Embryologic neck
What does the pronephric tubule look like?
primitive nephron (C-shaped with capillaries and large tubule coming off of one end)
Is the pronephric kidney functional?
No
What does the pronephric tubule connect to?
pronephric duct
What does the pronephric duct become/what is it retained as?
mesonephric duct
How many tubules does the pronephric kidney have?
7-8
How many tubules does the mesonephric kidney have?
70-80
What do mesonephric tubules look like?
Like pronephric tubules; glomerulus at one end, mesonephric duct at the other end
When does the mesonephric kidney begin to degenerate?
Once it reaches its maximum size
Which way does the mesonephric kidney degenerate?
Cranial –> caudal
What do the remnants of the mesonephric kidney give rise to?
Ovaries and testicles
In MALES, what 3 things do the caudal mesonephric tubules and duct give rise to?
- Testicular channels
- Epididymis
- Ductus deferens
What two structures give rise to the metanephric kidney?
- Metanephric diverticulum
2. Metanephrogenic mass
What are the 2 steps in the formation of the metanephric kidney?
- Metanephric diverticulum invades surrounding mesoderm from the mesonephric duct
- Surrounding mesoderm differentiates into the metanephrogenic mass
Off of where does the metanephric diverticulum branch?
mesonephric duct
What does the metanephric diverticulum give rise to?
Urine-conducting part of kidney (Ureter, renal pelvis, calyxes, collecting ducts); gets urine from kidney to bladder
What does the metanephrogenic mass give rise to?
Nephrons that produce urine
What are the 3 steps to nephron formation?
- Metanephrogenic mass differentiates into renal vesicles
- Renal vesicles differentiate into metanephric tubules
- Metanephric tubules connect to collecting ducts
What structure gives rise to the collecting ducts?
metanephric diverticulum
When does nephron formation occur?
at or around the time of birth
Can adult animals form new nephrons to replace damaged ones?
No
How many nephrons does the feline kidney have?
200,000
How many nephrons does the canine kidney have?
300,000-500,000
How many nephrons do the pig and ox kidneys have?
1.5 - 4 million
Why are there variations in macroscopic appearance of kidneys in different species?
Differences in interactions between metanephrogenic mass and metanephric diverticulum.
What 2 things give rise to the urinary bladder?
- Expansion of urachus
2. Cranial end of urogenital sinus
What 2 things does the caudal end of the urogenital sinus give rise to in the male?
- Pelvic urethra
2. Penile urethra
What 3 things does the caudal end of the urogenital sinus give rise to in the female?
- Pelvic urethra
- Vestibule
- Caudal vagina
What does the mesonephric duct give rise to in males?
Ductus deferens
What does the metanephric diverticulum give rise to?
ureter
What are the 6 steps to duct incorporation/reorganization?
- Developing bladder expands dorsally
- Mesonephric duct and metanephric diverticulum are incorporated into the bladder
- Bladder wall grows at different rates
- Ureter’s opening switches from urethra to bladder
- Ductus deferens’ opening switches from bladder to urethra
- Trigone area is formed
What are the 6 malformations that can happen during kidney formation?
- Renal agenesis
- Renal dysplasia
- Renal hypoplasia
- Ectopic kidneys
- Patent urachus
- Ectopic ureter
What is renal agenesis?
No kidney develops
What is renal dysplasia?
Abnormal development of kidney
What is renal hypoplasia?
Underdevelopment of kidney
What is an ectopic kidney?
Kidney sits in the pelvis
What is the purpose of the urachus in development?
Provides a route for urine to leave the body into the allantoic cavity
When does the urachus close? What do you have if it doesn’t close?
At or around the time of birth; patent urachus if doesn’t close
What 2 ways can urine flow after the membrane at the urogenital orifice degenerates?
- Down urachus into allantoic cavity
2. Down urethra into amniotic cavity
What can happen if there is a patent urachus?
Can cause bacterial infection
Where does the ectopic ureter open?
Males = urethra Females = urethra or vagina
In what species is an ectopic ureter common?
Dogs
What is the indifferent stage of development?
Stage where the embryo is not yet set on XX or XY
What 2 structures are present at the indifferent stage of development and what does each give rise to?
- Mesonephric duct = male structures
2. Paramesonephric duct = female structures
What two substances does the testis release?
- Müllerian inhibiting substance
2. Testosterone
What does Müllerian inhibiting substance do?
Suppresses mesonephric ducts
What does testosterone do?
Stimulates mesonephric ducts and external genitalia
What substance does the ovary release?
Estrogen
What does estrogen do?
Stimulates paramesonephric ducts and external genitalia
Where do germ cells develop?
Caudal part of the yolk sac
Where do germ cells end up after they leave the yolk sac?
Genital ridge
What forms gonadal cords?
Disintegrating mesonephric tubules
What are the 3 steps of testicular development?
- Mesonephric tubules disintegrate
- Mesonephric duct –> ductus deferens
- Paramesonephric duct degenerates
What does the part of the mesonephric tubule that does not disintegrate become?
seminiferous tubules, rete testis, efferent ductules
What are the 5 steps to testicular descent?
- Gubernaculum tethers developing testicle to scrotum
- Mesenchymal cells pump HA into gubernaculum, attracts water
- Gubernaculum, inguinal canal, and scrotum expand
- Cells of gybernaculum remove HA
- Gubernaculum shrinks and regresses completely
What are the 2 remnants of the gubernaculum in the adult male?
- Ligament of the tail of the epididymis
2. Proper ligament of the testis
