Typical and Atypical Development of the Reproductive Tract

Comprehensive vocabulary flashcards covering the embryologic development of the reproductive tract and associated differences in sexual development (DSD) based on the lecture transcript.

Differences of Sexual Development (DSD)

Congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical; medical terminology for variations that stray from typical development.

Intersex

A generalized term used to describe sexual development including chromosomes, gonads, sex hormones, or genitals that does not fit the typical definitions for male and female bodies.

Primordial germ cells

The direct precursors to sperm or ova that migrate from the embryonic yolk sac to the gonadal ridge approximately $4-5$ weeks post-conception.

Gonadal dysgenesis

The failure of germ cells to arrive at the gonadal ridge, resulting in non-functional 'streak', hypoplastic, or dysplastic gonads.

SRY

The Sex-determining Region of the Y chromosome; a gene region necessary for testes formation.

Testes Determining Factor (TDF)

The protein product of the SRY gene that leads to the formation of testes; its absence or mutation leads to non-functioning gonads in an $46, XY$ individual.

Swyer Syndrome

A form of $46, XY$ gonadal dysgenesis caused by mutations in genes like SRY; results in no testes, no testosterone, the development of a uterus/vagina, and typical female external genitalia.

Turner Syndrome

A sex chromosome disorder characterized by the absence of two normal X chromosomes ($45, X$), leading to 'streak' ovaries and infertility.

Leydig cells

Cells within the testes responsible for producing testosterone.

Sertoli cells

Cells within the testes that produce Antimullerian Hormone (AMH), also known as Mullerian Inhibiting Substance (MIS).

Wolffian duct

Also known as the mesonephric duct; under the influence of testosterone, it differentiates into the epididymis, vas deferens, and seminal vesicles.

Mullerian duct

Also known as the paramesonephric duct; it develops into the fallopian tubes, uterus, and upper portion of the vagina in the absence of AMH.

Dihydrotestosterone (DHT)

A potent androgen converted from testosterone by the enzyme $5 \text{ alpha reductase}$; it is necessary for the development of male external genitalia.

Uterine didelphys

A Mullerian anomaly caused by a fusion defect resulting in two separate uterine bodies and two cervices.

Septate uterus

A Mullerian anomaly caused by a canalization (resorption) defect where a septum remains within the uterine lumen.

Unicornuate uterus

A Mullerian anomaly resulting from agenesis on one side, which increases risks for miscarriage and intrauterine growth restriction (IUGR).

Mayer-Rokitansky-Kuster-Hauser syndrome

A condition characterized by the congenital absence of the uterus and the vagina.

Persistent Mullerian Duct Syndrome (PMDS)

A condition in $46, XY$ individuals where testes are present and produce testosterone, but the absence of functional AMH prevents Mullerian duct regression, resulting in both male internal organs and a uterus/tubes.

Androgen Insensitivity Syndrome (AIS)

An X-linked recessive $46, XY$ DSD where testes produce testosterone and AMH, but a defect in the androgen receptor prevents virilization, often resulting in female external genitalia and a short blind-ended vagina.

$5 \text{ alpha reductase}$ deficiency

An autosomal recessive $46, XY$ DSD where testosterone cannot be converted to DHT, resulting in undervirilized or female-appearing external genitalia at birth that may virilize at puberty.

Congenital Adrenal Hyperplasia (CAH)

The most common cause of ambiguous genitalia in $46, XX$ individuals, caused by over-exposure to androgens in-utero resulting in virilization.

Hypospadias

A male external genitalia malformation caused by the failure of the urethral folds to fuse, leading to an opening on the inferior surface of the penis.

Klinefelter syndrome

A sex chromosome disorder ($47, XXY$) characterized by small testes, breast development (in $30 \text{\%}$ of cases), and a slightly feminized physique.

Genital tubercle

An embryologic structure that becomes the glans of the penis in males or the clitoris in females.

OHVIRA

Acronym for Obstructed Hemi-vagina with Ipsilateral Renal Anomaly; often seen with uterine didelphys where $99 \text{\%}$ of cases also have an absent kidney on the same side.