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56 Cards in this Set

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  • Back
What does the Bladder develop from?
Subdivision of the cloaca
What is the cloaca?
The terminal end of the hindgut; a common area for the opening of the newly formed GI and UG ducts.
How does the CLOACA get subdivided to separate the UG and GI systems?
By formation of the Urorectal Septum.
What closes the Cloacal membrane off from the exterior? Where does it extend between?
The Cloacal Membrane extending from the Allantoic stalk to tailbud.
What does the Urorectal Septum subdivide the cloaca into?
1. Primary UG sinus (ventral)
2. Anorectal Canal (dorsal)
What IS the Urorectal Septum?
A wedge of mesenchyme between the allantois and hindgut
What happens to the Urorectal septum?
It grows ventrally, fuses with the cloacal membrane to form the Perineal Body
How does an exterior opening in the UG duct develop?
By apoptosis of the Cloacal membrane - probly due to pressure from urine.
What happens to the Primary UG Sinus?
Gets subdivided into:
-VesicoUrethral Canal (VU)
-Definitive UG Sinus
What determines the point of Primary UG Sinus subdivision?
Point of entry of the mesonephric duct
What develops from the VU canal?
-Part of urethra
What is the apical part of the VU canal continuous with, and what does it eventually form?
-Contin. w/ Allantois
-Becomes fibrous Urachus (remn)
In the Bladder what derives the:
-Epithelial lining
Epithelium = endodermal tissue
Walls = Splanchnic mesoderm
What happens to the Mesonephric duct distal to the Ureteric bud?
Forms the TRIGONE of the bladder as it is absorbed into the posterior bladder wall.
What is the fate of the Mesonephric ducts in
Females: atrophy
Males: vas deferens - allows it to dump into the bladder.
What happens to the bladder after birth?
Descends, drags urachus with it
What part of the urethra is formed from the VU canal in Males?
Only the proximal portion of the prostatic urethra.
What part of the urethra is formed from the VU canal in females?
Most of it
What is the caudal (lower) part of the UG sinus called (after separation from VU canal)?
Definitive UG Sinus - below the entry point of Mesonephric duct.
What develops from the Definitive UG Sinus?
2 subdivisions:
-Pelvic part (proximal)
-Phallic part (distal)
Fate of Pelvic part of Definitive UG Sinus in MALES:
-Distal prostatic urethra
-Membranous urethra
Fate of Pelvic part of Definitive UG Sinus in FEMALES:
Lower 1/2 of vagina
Fate of Phallic part of Definitive UG Sinus in MALES:
Penile urethra
Fate of Phallic part of Definitive UG Sinus in FEMALES:
2 Types of Anomalies associated w/ Urinary Bladder development:
1. Urachal anomalies
2. Exstrophy of the Bladder
What are 3 Urachal anomalies?
1. Urachal cysts
2. Vesical diverticulum
3. Vesico-umbilical Fistula
What are Urachal cysts derived from?
Epithelial lining of the urachus
What is a Vesical Diverticulum?
A communication of the bladder and a urachus remnant.
What is a Vesico-umbilical fistula?
Patent Urachus - communication of the bladder with the umbilicus - can cause presence of urine at the umbilicus.
What sex is Exstrophy of the bladder more common in?
Males - 3.5 x more common!
What IS Exstrophy?
Eversion of a hollow organ, so that its lining is exposed to the surface.
What is the cause of Bladder Exstrophy?
Ventral Body wall Defect - interferes with migration of muscle progenitors.
What are the 3 key features of Exstrophy of the Bladder?
1. Epispadius
2. UG/Skeletal anomalies
3. Exposed lining of posterior bladder to ventral body surface.
What is a much more severe form of Extrophy down there?
Exstrophy of Cloaca - includes both UG and GI anomalies
What is Epispadius?
Dorsal opening of the penile urethra
What 2 anomalies are associated with urethra development?
1. Agenesis/atresia
2. Posterior urethral valves
What sex is urethral agenesis more commonly associated with?
What syndrome is urethral agenesis associated with?
Prune belly - due to atresia of abdominal wall muscles.
What is the important thing to remember about Posterior Urethral Valves?
-ONLY in males
-Tissue folds of posterior urethra mucosa act like valves and obstruct it.
What makes Posterior urethral valves significant?
Most common cause of uropathy leading to renal FAILURE in children.
What is the ORIGIN of the Adrenal Cortex?
Coelomic Epithelial cells & possibly cells from mesonephros.
How does the fetal adrenal cortex form?
Chords of epithelial cells extend into underlying UG Ridge
How does the Fetal adrenal cortex compare to adult?
20X larger; composes 80% of total adrenal gland in fetus.
What stimulates development of the fetal adrenal cortex?
Early: hCG
Later: ACTH
When does the fetal adrenal cortex begin to shrink?
At birth; completed by 6 mo-1yr
What is inactive in the fetal cortex, and what is the consequence?
3b-hydroxysteroid dehydrogenase
-Can't make progesterone or androstenedione.
What is the DEFINITIVE adrenal cortex?
At birth, a thin layer external to the fetal cortex.
What will the definitive cortex develop into?
3 zones - glomerulosa, etc..
What is "materno-feto-placental unit"?
Cooperation of mother/fetus to increase estrogen production by the placenta - makes gluco- and mineralcorticoids.
What does the Adrenal MEDULLA derive from?
Neural Crest cells - invade the cortex and move centrally.
What 3 parts of the medulla develop from these neural crest cells?
-Chromaffin tissue
-Glandular cells
What are 2 forms of abnormal adrenal development?
1. Congenital Adrenal Hyperplasia
2. Adrenal hypoplasia
What is the main feature of CAH?
Genetic defic in hydroxylase enzyme production
What results from CAH?
-Increased ACTH
-Increased androgens
-Adrenal hyperplasia
What happens to CAH Patients if
Male: precocious development of external genitalia

Female: masculinized external genitalia
What is Adrenal Hypoplasia associated with, & what results?
-Assoc w/ Anencephaly
-No pituitary - no ACTH