197. UG Development Flashcards
When do males and females differentiate in utero? What structures are male and what are female?
What become of the following UG primordia?
- Intermediate Mesoderm
- Splanchnopleure of Hindgut
- Somatopleure
W8
Mesonephric duct = males
Paramesonephric duct = females
IM - Kidney/Gonads
Hindgut - bladder/urethra
Somatopleure - genitals (Genital tubercle = swelling of somatopleure in perineum)
UG Ridge
- what is it
- what does it contain (2)
- how do primordial germ cells develop?
- how do the ducts develop?
Intermediate mesoderm that bulges into peritoneal cavity
1. Nephrogenic cord (kidney)
2. Gonadal Ridge (gonads) - thickening epithelium
Germ cells migrate from hindgut into gonadal ridges (surrounded by epithelial sex cords that project into primitive gonad)
Paramesonephric duct: invagination of surface that persists as opening of uterine tubes, both sides join to form uterus/vagina
Mesonephric duct: condensations of intermediate mesoderm (nephrogenic cord) = becomes female ureter, or male ductus deferens (changes fx from urine to genital)
What are the 3 sequential kidneys during development?
How does the mesonephric duct form? drain? what originates from it?
What does the metanephros include (2) - what do they give rise to?
How does the kidney get to it’s place in the neonate?
What is horseshoe kidney?
- Pronephros (Cranial, vestigial)
- Mesonephros (Huge, first fx-ing)
- Metanephros (Caudal, kept as adult)
Mesonephric duct: joins mesonephric tubues of first functioning kidney, drains into cloaca (hindgut dilation), becomes first (temporary) ureter, AKA wolffian duct; Metanephric diverticulum (ureteric bud) originates from mesonephric duct (mesodermal origin)
Metanephros: 1. Ureteric bud (from mesonephric duct, gives rise to ureters, renal pelvis, calyces, collecting tubules in pyramids), 2. metanephric mass of intermediate mesoderm - gives rise to kidney nephrons
Kidneys ascend as mesonephros degenerates downwards; as kidney ascends, sequential arteries hook up to it; ureters and blood vessels are anterior to developing kidney
Horseshoe Kidney: fusion of ureteric buds around IMA as they ascend
UG Sinus (Cloacal Separation)
- what divides cloaca?
- three parts of UG sinus
- what occurs due to improper cloacal division?
- what happens to allantois?
- what is exstrophy of bladder/cloaca?
Urorectal Septum divides cloaca into rectum and UG Sinus (Mesodermal)
1. Bladder, 2. Pelvic, 3. Phallic = all continuous with allantois (vestigial)
Improper division: Fistula & imperforate anus (rectum + perineum/urethra/bladder/vagina)
Allantois: becomes fibrous cord (Urachus) from naval to top of bladder, may persist as cyst, sinus, fistula
Exstrophy of bladder/cloaca: failure of mesoderm migration into cloacal membrane/ventral abd wall = breakdown of ant bladder wall exposing mucosa
- bladder breaks thru abd wall
- cloaca breaks down and hindgut breaths thru body wall
Sexual Differentiation
- how do testes develop?
- how do ovaries develop?
- how do external genitals develop (derivatives)?
- what is hypospadius?
Testes: Primary sex cords = seminiferous tubules = sertoli cells (through whole thickness of testes), no secondary sex cords
Ovaries: Primary sex cords: vestigial rete ovarii
Secondary sex cords = ovarian follicles (near cortex) = Granulosa cells
Genitalia
- Labioscrotal folds: flank UG folds + genital tubercle = Labia majora or scrotum
- Lower UG Sinus: female vestibule; male penile urethra
- UG Folds: female labia minora
- Clitoris = Penis
- Penile Urethra: most from ventral fusion of UG sinus, navicular fossa = ectodermal invagination
Hypospadius: failure of UG folds to fuse
- urethral opening on ventral surface of penis
What are the adult derivatives of the UG sinus? Mesonephric Duct? Paramesonephric duct?
UG Sinus: Bladder, Urethra, Paraurethral Glands, Uterus, Upper vagina, vaginal plate, greater vestibular gland
Mesonephric Duct: Ureter (Male: Epididymus, Efferent Ductules, Ductus Deferens, Seminal Vesicles, Ureters)
Paramesonephric Duct: Uterus, Uterine Tube
Ovary: intermediate mesoderm
