Sex Determination & Development Flashcards

Vocabulary practice flashcards generated from lecture notes on sex determination, developmental genetics, embryonic reproductive tract formation, and brain sexual dimorphism.

Barr body

The inactive X chromosome visible in the somatic cells of female mammals.

Virilization

The biological development of male sex differences and masculine characteristics, primarily induced by androgen hormones.

True Hermaphrodite

A congenital condition of sexual development where an individual (most commonly $XX$) possesses a combination of ovaries, testes, and ovotestes.

Male Pseudohermaphrodite

An individual with an $XY$ chromosomal sex and testes (typically internal) who exhibits female or ambiguous external genitalia.

Female Pseudohermaphrodite

An individual with an $XX$ chromosomal sex and ovaries who exhibits masculinized or male external genitalia, often caused by Congenital Adrenal Hyperplasia.

Freemartin

A sterile female calf born twin to a male calf as a result of placental anastomosis that enables male hormones and blood cells to cross into the female fetus.

Klinefelter's Syndrome

An abnormal condition ($XXY$ syndrome) resulting from a nondisjunction event, leading to sterility and testicular hyperplasia.

Turner's Syndrome

A condition characterized by a monosomy X genotype ($XO$) occurring in $1$ out of every $2500$ female births, leading to sterile females with inactive ovaries.

Swyer Syndrome

Also known as pure gonadal dysgenesis, a condition featuring a $46, XY$ karyotype, female external genitalia, normal vagina and uterus, but nonfunctional streak gonads.

Leydig Cell Hypoplasia

A form of male pseudohermaphroditism caused by inadequate fetal testicular Leydig cell differentiation, despite having a functional androgen receptor.

H-Y Antigen

A male-specific histocompatibility protein present on the cell surfaces of male ($XY$) mammals.

SRY Gene

The Sex-determining Region Y gene located on the Y chromosome that directs sex determination and stimulates male sexual development.

Pronephros

A nonfunctional, primitive renal system that regresses early during embryonic development.

Mesonephros

The intermediate, functional kidney that is drained by the mesonephric ducts and contributes to the formation of the male reproductive duct system.

Metanephros

The adult functional kidney in mammals, which develops during the first $1/3$ of gestation from a bud on the caudal mesonephric duct.

Mesonephric Ducts

Also known as Wolffian ducts, these embryonic ducts develop into male reproductive structures including the epididymis and ductus deferens.

Paramesonephric Ducts

Also known as Müllerian ducts, these embryonic ducts fuse to form female reproductive structures including the oviducts, uterus, cervix, and cranial vagina.

Anti-Müllerian Hormone (AMH)

A glycoprotein hormone secreted by fetal Sertoli cells that causes regression and degeneration of the paramesonephric ducts in male embryos.

$5\alpha$-reductase Deficiency

A genetic condition where $XY$ males lack the enzyme to convert testosterone into $5\alpha$-dihydrotestosterone, resulting in external female genitalia with internal testes.

Alpha-fetoprotein (\alpha FP)

A protein produced by the fetal liver that binds fetal estrogen ($E_2$) to prevent it from crossing the blood-brain barrier in females.

SDN-POA

The Sexually Dimorphic Nucleus of the Preoptic Area in the brain, which in males has $2.2$ times the volume and $2.1$ times the cell count of females.

Surge Center

A hypothalamic center responsible for preovulatory GnRH surges that develops in female brains but is defeminized (prevented from developing) in male brains by estrogen derived from aromatized testosterone.