Sex Determination and Differentiation - Test 1 Flashcards
The presence of what gene is responsible for the first steps in male sex organ development?
SRY gene
SRY gene results in the development of _______.
Testicles
During fetal developmemnt, Leydig cells make ______ and sertoli cells make ______.
leydig –> testosterone
sertoli cells –> anti-mullerian hormone
Which hormones are responsible for stimulating the development of internal and external male genetalia development, respectively?
Internal: testosterone
External: DHT
Which hormone stimulates Leydig cells to secrete testosterone early on during male fetal development?
hCG from the placenta (syncitiotrophoblasts)
What gene inhibits the formation of Leydig cells and induces the formation of Mullerian ducts in a female?
WNT4
Internal male genital structures derive from the _________ _______. They include what adult structures?
Wolffian/mesonephric duct
Vas defrens
Epididymis
Seminal vesicles
Ejaculatory duct
Internal female genital structures form from the ________ ______ and include…?
Mullerian/paramesonephric duct
Fallopian tubes
Uterus
Upper 1/3 of the vagina (lower 2/3 forms from the urogenital sinus)
What is a differential Dx for ambiguous genitalia in a genetic XY infant?
5-alpha-reductase deficiency (no DHT –> no extenal genitalia)
SRY deletion (female internal and external genitalia)
Androgen insensitivity syndrome (female external genitalia but not internal due to presence of AMH, testis may be in the inguinal canal or in the labia majora)
Defects in testosterone synthesis (same presentation as androgen insensitivity syndrome)
17-alpha-hydroxylase deficiency due to inability to synthesize testosterone
What is the differential diagnosis for ambiguous genitalia in a genetic XX infant?
21-hydroxylase deficiency
11-hydroxylase deficiency
Mullerian agenesis/dysgenesis
Ovotesticular (somehow there is presence of SRY gene)
What is the genetic makeup of a Klinefelter patient and what are the signs/symptoms?
47, XXY or more
Usually diagnosed later in life…
Gynecomasita and feminine body habitus
Small, firm testes
Mental retardation
Azoospermia
Leydig cell hyperplasia on histology
What is the genetic makeup of a patient with Turner’s syndrome and what are the signs/symptoms?
45, X
Female external genitalia
No ovaries (it is fibrous tissue instead - streak ovaries)
Short stature
Retruded mandible
High-arched palate
Auditory deficits
Short, broad neck
Low nuchal hair line
Shield-like chest
Left-sided heart disease: bicuspid aortic valve, coactation of the aorta
Malrotated or horseshoe kidneys
Multiple pigmented nevi
Hypoplastic and hyperconvex nails
Cubitus valgus (wide carrying angle)
Amehorrhea
What is the treatment for Turner’s syndrome?
Anabolic steroids and GH
Estrogen and progesterone at puberty
How do you treat Klinefelter’s and other DSDs associated w/ testosterone deficiency?
Low-dose testosterone
What is the treatment for 21-hydroxylase deficiency?
Glucocorticoids and mineralocorticoids (cortisol and aldosterone) + sodium supplementation
