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Savion, 3/15 Also know stages of folliculogenesis, oogenesis, etc.

External genitalia; genital ducts; gonads

The genital system is composed of these three general parts

Epididymis; ejaculatory duct; vas deferens

The adult derivatives of male genital ducts (3)

Uterine tubes; uterus; vagina

The adult derivatives of female genital ducts (3)

Genital ducts (connect gonads to external genitalia)

This part of the genital system connects the other two parts (general)

Female

This sex is the default mechanism

Male

This sex requires a signal for the production of its genital system

Urogenital ridges

Two ridges formed in fourth week by intermediate mesoderm being pushed ventrally by lateral folding into intraembryonic coelom

Intermediate; lateral; intraembryonic coelom

The urogenital ridges are form in week 4 by ____ mesoderm being pushed ventrally by (head/lateral) folding into the ____

Intermediate

Urogenital ridges are composed of ____ mesoderm

Urogenital ridges

The genital and urinary system are derived from these folds created in the fourth week

Genital

The (genital/urinary) system is derived from the medial edge of the urogenital ridge

Urinary

The (genital/urinary) system is derived from the lateral urogenital ridge

Primary sex cords (for testes/ovary); primordial germ cells (PGC)

The indifferent gonad contains these two different cell types/clusters in week 5-6

Primordial germ cells

PGC

Primary sex cords (gonadal cords)

At medial edge of urogenital ridge, mesoderm proliferates producing these finger-like projections; composed of inner medulla and outer cortex

Males

In (females/males), the medulla develops into the gonads and the cortex regresses

Females

In (females/males), the cortex develops into the gonads and the medulla regresses

Cortex

The (cortex/medulla) develops into ovaries in females while the other regresses

Medulla

The (cortex/medulla) develops into testes in males while the other regresses

Males (Wolffian = mesonephric ducts)

In (females/males), the Wolffian ducts develop into the genital ducts and the Mullerian ducts regress

Females (Mullerian = paramesonephric ducts)

In (females/males), the Mullerian ducts develop into the genital ducts and the Wolffian ducts regress

Mullerian (paramesonephric ducts)

The (Mullerian/Wolffian) develops into the uterine tubes and uterus in females while the other regresses

Wolffian (mesonephric ducts)

The (Mullerian/Wolffian) develops into the epididymis, vas deferens, efferent ducts in males while the other regresses

Paramesonephric

The Mullerian ducts are the (mesonephric/paramesonephric) ducts; give rise to female genital ducts

Mesonephric (also drain temporary kidney)

The Wolffian ducts are the (mesonephric/paramesonephric) ducts; give rise to male genital ducts

Primitive streak (from the epiblast)

Primordial germ cells are derived from this

Yolk sac (gut)

In the 5-6th week, the PGC migrate from the ____ through the dorsal mesentery to the developing gonads where they wait for a signal

Paramesonephric

The (mesonephric/paramesonephric) ducts are more lateral

Mesonephric (Wolffian) ducts; paramesonephric (Mullerian) ducts

At the indifferent stage, an embryo contains these two sets of ducts

At fertilization

When sex is determined

SRY (region and protein)

This is necessary for development of male genital system; cause medullary sex cord cells to become AMH (anti-Mullerian hormone) producing sertoli cells

SRY

The sex-determining gene for males

AMH

Production of SRY protein by medullary sex cord cells results in their differentiation to sertoli cells which then secrete this; this induces degeneration of paramesonephric ducts

Sertoli cells

These cells differentiate from medullary sex cord cells; produce AMH (anti-Mullerian hormone); form seminiferous tubules

Sertoli; leydig

The SRY protein has two effects, causes differentiation of: medullary cord cells to ____ cells; mesenchymal cells between cords to ____ cells

Leydig cells

SRY signals the mesenchymal cells between the seminiferous tubules to differentiate into these; produce testosterone

Testosterone

This hormone gives rise to most of male genital system; in puberty, initiates spermatogenesis and development of secondary sex characteristics in males

AMH (anti-Mullerian hormone); DHT (dihydrotestosterone); testosterone

These hormones are important in development of the male genital system (3)

DHT (dihydrotestosterone)

This hormone is responsible for development of external male genitalia, prostate, and other structures; derived from testosterone

7

If SRY is present, the male genital system starts to develop at week __

Leydig cells; sertoli cells; spermatogonia

The cells found in the testes (3)

Specific germ cells

Once indifferent gonad starts to differentiate, PGC become these

Efferent ducts (efferent ductuli); vas deferens

Sperm travel through seminiferous tubules to rete testes to ____ to epididymis to ____

Granulosa cells

These cells differentiate from cortical sex cord cells; these form follicles

10

If SRY is not present, the female genital system starts to develop at week __; medulla regresses

Urethra (all of female, most of male; caudal); urinary bladder (medial)

These develop from the urogenital sinus; lined by endoderm

Testosterone

(AMH/DHT/Testosterone) production leads to formation of male genital duct system: epididymis, ejaculatory duct, and ductus deferens

Efferent ducts (efferent ductuli)

These are derived from the few persistent tubules from the mesonephric duct; part of testes

Paramesonephric

Without SRY and AMH, the (mesonephric/paramesonephric) ducts persist while the other degenerates

Uterus

The fusion of part of the paramesonephric ducts produce this adult structure

Uterine tubes

The unfused part of the paramesonephric ducts produce this adult structure

Uterus; uterine tubes

The paramesonephric ducts give rise to these adult derivatives

Urogenital sinus (urinary bladder)

The vagina is derived from this

Vagina

The septum/diverticulum outgrowth which forms when the uterus makes contact with dorsal wall of bladder becomes this; elongates and communicates with uterus

Hymen

This closes the vagina; from bladder; ruptures before birth leaving ring of CT around orifice of vagina

Abdomen (must descend to pelvis/scrotum; descent begins in week 7 for testes)

The gonads begin development here

Testosterone

Descent of the testes (to outside of the body) is at least partially controlled by this hormone (control not well understood)

7; 28

The first part of the descent of the testes begins in week (7/8/9) and ends in week (26/28/30)

Gubernaculum ligament

This structure aids in first part of descent of testes

Most caudal part of abdomen

The testes descend to here in first part of descent, aided by gubernaculum ligament

Scrotum (outside of body)

The testes descend to here in second part of descent, aided by processus vaginalis

Processus vaginalis (peritoneal fold)

This structure aids in second part of descent of testes

Processus vaginalis

Peritoneal fold; forms inguinal canal; pulls abdominal wall with it as it descends; testes pass posterior to this into scrotum (still attached to gubernaculum)

Inguinal canal

The testes pass through this into scrotum; after testes pass, it closes (in humans)

95

(35/60/95)% of full term male babies' testes are in their scrotum

Scrotal ligament

Adult derivative of gubernaculum ligament; keeps testis invested in scrotum

Anterior

The tunica vaginalis is (anterior/posterior) to the testes

Tunica vaginalis

This is the remnant of the processus vaginalis, after connecting stalk (to abdomen) degenerates

Ovarian ligament (connects ovary to lateral surface of uterus); round ligament (connects uterus to labia majora, for anteversion)

Adult derivatives of gubernaculum ligament in females (2)

3

The ovaries descend from the abdomen to the pelvis in month (3/4)

Gubernaculum ligament

This structure aids descent of ovaries

Processus vaginalis

A very small inguinal canal formed by this usually degenerates in females

Canal of Nuck

A persistent remnant of the processus vaginalis (inguinal canal) in females; usually asymptomatic

12

Development of external genitalia occurs between week 7 and week (12/14/16)

Labioscrotal swellings; urogenital folds

The two pairs of folds which form during indifferent stage; form around cloacal membrane in weeks 4-7

Urogenital folds

These are the inner, smaller folds of the indifferent external genitalia

Labioscrotal swellings

These are the outer, larger folds of the indifferent external genitalia

Phallus

This diverticulum develops cranial to cloacal membrane in weeks 4-7

Anal membrane; urogenital membrane

These are formed after complete division of cloacal membrane (by urorectal septum)

Phallus

This elongates, pulling (both pairs of) folds cranially, starts to close urethra (occurs in males and females)

Phallus

In males, this elongates, pulling folds cranially until entire urethra is closed; forms glans penis

Glans penis

Ectodermal ingrowth communicates with urethra here; tip of the penis

Phallus (pulls urogenital folds and labioscrotal swellings cranially; closes urethra)

In males, all external genitalia seems to depend on elongation of this

Phallus

In females, this elongates then stops, becomes smaller; forms clitoris

Clitoris; glans penis

Adult derivatives of phallus (in males and females)

Labia minor; (most of) penis

Adult derivatives of urogenital folds (in males and females)

Labia majora; scrotum

Adult derivatives of labioscrotal swellings (in males and females)

Hermaphroditism (intersexuality)

Malformation; a discrepancy between the gonads, genital ducts and external genitalia; general term

Female pseudohermaphroditism; male pseudohermaphroditism; true hermaphroditism

Three types of hermaphroditism

True hermaphroditism

Rare malformation; may occur in genetic males with SRY mutation, genetic females with SRY translocation, or mosaics; has testicular and ovarian tissue; ambiguous external genitalia

Ovotestis

A true hermaphrodite may have this; a single organ with both testicular and ovarian tissue

Male pseudohermaphroditism

Malformation; genetic males with female external genitalia; results from inadequate testosterone or DHT production, or abnormal androgen receptors

Male pseudohermaphroditism

This condition is generally discovered at puberty; abnormal testes removed; individual is considered psychologically female; no uterus due to AMH

Testicular feminization syndrome (androgen insensitivity syndrome)

A form of male pseudohermaphroditism; caused by abnormal androgen receptors

Male pseudohermaphroditism

5α-reductase deficiency can cause this malformation in genetic males

Female pseudohermaphroditism

Malformation; genetic females with male external genitalia; results high level of androgens; may be caused by CAH or agents for spontaneous abortion treatments

Congenital adrenal hyperplasia

CAH

Congenital adrenal hyperplasia (CAH)

Excessive androgen production by the fetal adrenal glands; results in (a possible cause of) female pseudohermaphroditism

Female pseudohermaphroditism

Malformation; might get menses; connection between uterus and urethra; enlarged clitoris; results from high levels of androgens

Cryptorchid testes; ectopic testes

Undescended testicle anomalies (infertile; 2)

Cryptorchid testes

Anomaly; undescended testicles; along the usual path of descent; might result from deficient androgen production; treat with testosterone if descent does not occur

Cryptorchid testes

Anomaly; undescended testicles; testes attached to gubernaculum ligament; failure of second process of descent

Ectopic testes

Anomaly; undescended testicles; deviate from usual path of descent, lodge in various abnormal locations

Ectopic testes

Anomaly; undescended testicles; testes not attached to gubernaculum ligament or error of gubernaculum ligament

Incomplete congenital inguinal hernia (herniated intestine can become necrotic)

Anomaly; may result from abnormal closure of inguinal canal; most cranial portion of processus vaginalis not obliterated

Hydrocele; complete congenital inguinal hernia; incomplete congenital inguinal hernia

These result from abnormal closure of processus vaginalis (3)

Hydrocele

Anomaly; accumulation of fluid in abnormally closed (or unclosed) processus vaginalis

Complete congenital inguinal hernia (herniated intestine can become necrotic)

Anomaly; may result from complete failure of processus vaginalis to obliterate

Hypospadias (common, esp in hermaphrodites)

Urethra opens on ventral (lower) surface of penis; ectodermal part is not canalized (no orifice at tip); results from inadequate testosterone and/or abnormal receptors

Epispadias (very rare; don't know mech)

Urethra opens on dorsal (upper) surface of penis; results from inadequate ectodermal-mesenchymal interaction; often associated with exstrophy of bladder

Agenesis of external genitalia (very very rare)

Anomaly; orifice for urethra but no male or female genitalia; results from inadequate ectodermal-mesenchymal interaction

Double uterus and vagina

Anomaly; abnormal fusion of paramesonephric ducts (very low)

Uterus; vagina (double uterus results in two vaginas)

In females, the ____ induces development of a ____

Bicornuate uterus

Anomaly; incompletely fused uterus; some fusion (and degradation of septum) complete caudally

Septate uterus

Anomaly; abnormal fusion of paramesonephric ducts; fusion complete, but has septum

Double uterus and single vagina

Anomaly; abnormal fusion of paramesonephric ducts, some fusion caudally

Bicornuate uterus with rudimentary horn

Anomaly; not fully fused uterus; one half is somewhat degenerated

Unicornuate uterus

Anomaly; half of uterus does not develop; only one paramesonephric duct develops

Hymen anomalies (incomplete perforation of hymen, septate h., cribriform h., stenotic h., imperforate h.)

This group of anomalies results from abnormal perforation of inferior end of vagina

Imperforate (completely closed)

The (cribriform/imperforate/septate/stenotic) hymen is the most severe anomaly caused by abnormal perforation of inferior end of vagina

Vaginal atresia

Anomaly; failure of canalization of vaginal plate

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