Flashcards in Development of the Genital System Deck (39)
What is the coelomic epithelium?
What does it give rise to?
Outer somatic mesoderm that lines the urogenital ridge.
Primary sex cords.
Where are the primordial germ cells found?
In the allantois/yolk sac endoderm.
Primordial germ cells of men and women:
Men: Sertoli cells and Leydig cells.
Women: follicle cells and thecal cells.
Migration of gametes and timeline
Arise from the epiblast in wk 2 and migrate through the primitive streak in wk 3 to reside in the yolk sac and allantois.
MIgrate back via dorsal mesentary in wk 5.
Colonize the primary sex cords in wk 6.
Amount of oogonia in:
5th prenatal month
5th prenatal month: 6 million
Birth: 1 million
Central event of sex determination:
Secondary events of sex determination:
Central event is the differentiation of the testes.
Secondary events are the production of humoral factors by gonads.
Upregulates testis-specific genes
XY mice w/o SRY
XX mice w/ SRY
Will demonstrate the opposite sex's characteristics but are sterile. Not hermaphrodites.
Draw the pathway of sex determination in men
Draw the pathway of sex determination in women
What happens when the is no AMH in males?
Male and female internal genitalia w/ male external genitalia.
What happens in a 5a-reductase deficiency (no DHT) in males?
Male internal genitalia w/ ambiguous/female external genitalia.
When does gonadal development occur?
Primary sex cords (medulla) does what in males and females?
Persists in males
Degenerates in females
What do the primary sex cords become in males?
Seminiferous tubules and Sertoli cells
Connective tissue in the males becomes?
Leydig cells and tunica albuginea
Secondary sex cords (cortical cords) becomes what in females?
Primordial follicles and granulosa cells
Thecal cells are from:
What happens to the mesonephric ducts in males and females?
Stays in males.
Degenerates in females to form epoophoron and paraophoron.
What happens to the paramesonephric ducts in males and females?
Degenerates in males and persists in females.
Mesonephric duct in males becomes (4)
Mesonephric tubules in males becomes (2)
How do the paramesonephric ducts create the uterine tubes and uterovaginal primordium?
Cranially, they remain separated to form the uterine tubes, and caudally they fuse to form the uterovaginal primordium.
How is the sinus tubercle produced?
The caudal portion of the paramesonephric duct (uterovaginal primordium) projects into the urogenital sinus (bladder) to create the sinus tubercle.
Formation of what is induced by the sinus tubercle?
What does it fuse to form?
Induces formation sinovaginal bulbs (endodermal outgrowths) which fuse to form the vaginal plate (precursor of vagina).
How does the vaginal plate form the mature vagina?
Epithelium will proliferate, then re-canalize to form the lumen of the vagina.
Prostate is from:
Pelvic part of urogenital sinus (endoderm) and splanchnic mesoderm (smooth muscle and CT).
Bulbourethral glands are from:
Phallic part of urogenital sinus (endoderm) and splanchnic mesoderm (smooth muscle and CT).
What hormone influences differentiation of male external genitalia?
Genital tubercle in males becomes:
Urethral (UG) folds in males becomes: (3)
In females: (1)
Lateral walls of urethra
Frenulum of labia minora
Labioscrotal swellings in men becomes:
In females: (2)
What hormone influences differentiation of female external genitalia?
What causes the completion of the spongy urethra?
Fusion of UG (urethral) folds.
What is the navicular fossa and how is it formed?
It is the spongy urethra at the glans penis.
It is formed by surface ectoderm.
Hypospadias is caused by:
Failure of the urogenital (urethral) folds close or the labioscrotal swellings to close.
How is epispadias caused?
Improper location of genital tubercles to cloacal membrane.
Associated with bladder problems.
What does the gubernaculum form in females?
The cranial part forms the ovarian l. and the caudal part becomes the round l. of the uterus.