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Endo/Repro Final > Development Of The Genital System > Flashcards

Development Of The Genital System Flashcards

1
Q

Name the week:

Indifferent embryo

Sexual differentiation begins

Female and male genitalia can be recognized

Phenotypic differentiation complete

A

Weeks 1-6

Week 7

Week 12

Week 20

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2
Q

What is the indifferent gonad?

Where do they end up after gastrulation and body folding?

Where and when do they migrate after that?

A

Primordial germ cells specified within epiblasts

Yolk sac wall

Migrate up dorsal mesentery to enter genital ridge; week 5

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3
Q

When is the gonad indifferent?

What are the male and female somatic support cells?

A

Week 6

Male: Sertoli cells

Female: follicle cells

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4
Q

Both genital ducts form in the ____ of the urogenital ridge.

What are the two ducts and what do they become?

Which duct was a part of early kidney development?

A

Intermediate mesoderm

Mesonephric (Wolffian) ducts: epididymis, vas deferens, seminal vesicle, ejaculatory duct

Paramesonephric (Mullerian) ducts: oviduct, uterus, upper vagina

Mesonephric (Wolffian) ducts

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5
Q

Sexual dimorphism is dependent on the ____ chromosome and ____.

____ gene is on the sex-determining region of the Y chromosome

What does this gene determine?

Without this gene, continued development is ____ with ____ positively driving this development.

A

Y; autosomes

SRY

The gonad type and duct and genitalia development

Female; genes

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6
Q

What gene determines the formation of testis?

What chromosome is it on?

When is it active?

What cells express this gene?

A

SRY gene (also called TDF/testis determining factor)

Y chromosome

41-52 days

Somatic support cells (pre-Sertoli)

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7
Q

What is the job of the SRY gene?

____ surround primordial germ cells to organize/become seminiferous tubules.

Subset of intertubular cells differentiated into _____; recruited by ______.

A

Up-regulates testis-specific genes; drives formation of Sertoli cells from somatic cells

Sertoli cells

Fetal leydig cells; Sertoli cells

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8
Q

This gene is driven by SRY

Function of this gene

What remnants are left from the paramesonephric duct in males?

A

Sox9

Drives the production of Anti-Mullerian Hormone (AMH) from the Sertoli cells -> inhibits development of Mullerian (paramesonephric) ducts between weeks 8-10

Appendix testis, prostatic utricle

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9
Q

Leydig-derived testosterone drives the development of what?

This will form what in males?

When does the paramesonephric duct degenerate in males?

A

Mesonephric ducts

Epididymis, efferent ductules, vas deferens, seminal vesicles

Week 9

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10
Q

Sertoli cells generate ____ which cause regression of _____.

Sertoli cells also generate ____ which causes spermatogonia to become spermatozoa during ____.

A

AMH; paramesonephric ducts

Androgen binding factor; spermatogenesis

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11
Q

When do fetal leydig cells regress?

What do fetal leydig cells produce and what is the fx?

A

Fetal/early post natal life

Testosterone: causes mesonephric duct to become the ductus deferens, epididymis, seminal vesicle during weeks 8-12; driven by HCG of placenta

5 alpha reductase: causes testosterone to become dihydrotestosterone (DHT)

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12
Q

DHT drives the formation of what?

Adult leydig cells secrete ____.

What do they do?

A

Genital tubercle -> penis
Genital swellings -> scrotum
Urethral epithelium -> prostate

Androgens

Initiation of spermatogenesis, masculinization of brain, male sexual behavior

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13
Q

Development of the external genitalia begins with ____ external genitalia.

Rupture of cloacal membrane opens the phallic portion of urogenital sinus to exterior, forming an endodermally-lined plate called what?

What are remnants of the cloacal membrane at the ventral end of urogenital plate?

What is the ectodermally-covered mesodermal swelling at ventral and cranial end of phallic portion of urogenital plate?

A

Indifferent

Urogenital plate (endodermally lined)

Glans plate

Genital tubercle (mesoderm covered by ectoderm)

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14
Q

What is the urogenital plate?

When does it form?

___ drives lengthening and growth of genital tubercle and fusion of labioscrotal swellings to form sacrum.

____ continues to elongate creating a future urethra inside a tube of ____.

When is the urethral groove closed?

A

Remnant of phallic segment after cloacal membrane rupture

Early 7th week

DHT

Urogenital plate with ventral glans plate; urogental folds

Week 14

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15
Q

Gonads start around ____ and descend.

What shortens and becomes the anchoring ligament of the testis to the scrotum?

It is connected to the ____.

A

T10

Gubernaculum

Labia/scrotal swelling

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16
Q

The most common birth defect after cryptorchidism; urethral folds on either side of UG plate don’t fuse; urethra opens in inferior side of penis

Other birth defect associated with exstrophy of bladder; problem with anterior wall closure of the bladder

A

Hypospadias

Epispadias

17
Q

Females don’t have ____, allowing ____ to initially suppress sox9 expression.

____ continually suppresses Sox9; maintaining female gonad (suppress Sertoli cell and Leydig cell differentiation).

Somatic cells differentiate into ____; primordial germ cells differentiate into _____.

Oogonia proliferate and differentiate into ____.

____ surrounds oocytes in inhibit further meiosis; oocytes stuck in meiosis I until ____.

A

SRY; Wnt4

FOXL2

Follicle cells; oogonia

Oocytes

Follicle cells; puberty

18
Q

In females, no Sertoli cells therefore no ____; paramesonephric ducts are retained.

No leydig cells so _____ is lost.

Persistence of Müllerian (paramesonephric) ducts creates ____.

A

AMH

Mesonephric duct

Uterine tubes, uterus, vagina (upper portion)

19
Q

When does the uterus form?

How does it formed?

What drives this formation?

____ are the unfused superior portion of the paramesonephric ducts.

What is a remnant of the mesonephric duct in females?

A

Weeks 9-10

Inferior paramesonephric ducts near the urogenital sinus fuse and form the uterus

Estrogen and progesterone from placenta

Uterine tubes

Gartner’s duct

20
Q

What are uterus anomalies?

How do these form?

A 
Double uterus; double vagina 
Double uterus
Bicornate uterus
Septated uterus
Unicornate uterus
Cervical atresia

Mainly formed because of lack of fusion of the paramesonephric ducts

21
Q

Paramesonephric ducts fuse on the _____; this stimulates formation of the ____.

What is the upper vagina derived from?

Lower vagina?

The vagina is eventually ___.

What causes vaginal agenesis?

A

Urogential sinus; sinovaginal wall

Mesoderm; from paramesonephric duct system

Endoderm; from sinovaginal wall

Recanalize

Due to failure of normal vaginal plate development or failed canalizations

22
Q

Phallic segment of the urogenital sinus forms what in the female?

Urethral portion of urogenital sinus becomes what?

A

Urogenital plate, glans plate, genital tubercle

Membranous urethra

23
Q

No testosterone leads to no dihydrotestosterone and therefore no _____ and ______ in females.

A

No lengthening of genital tubercle and no fusion of urogenital folds or labioscrotal swellings

24
Q

How does the broad ligament form?

Upon completion of uterus and oviduct formation, the remaining tissue thins and forms a _____ which supports ____.

A

Midline fusion of paramesonephric ducts; brings lower urogenital ridge within the pelvic cavity and is covered with peritoneum

Double fold of peritoneum (broad ligament and mesovarian); uterus and ovary

25
Q

Superior gubernaculum forms what?

Inferior gubernaculum forms what?

A

Round L of ovary (connects to uterus)

Round L of uterus (connects uterus to labia majora)

26
Q

What is pseudohermaphroditism/disorders of sex development (DSD)?

Genotypic sex is masked by ____.

A

Congenital conditions which development of chromosomal, gonadal, and anatomic sex is atypical

Phenotypic appearance resembling opposite sex or having reproductive organs of opposite sex

27
Q

What is 46, XY DSD (disorders of sex development)?

What disorders does this cause?

A

Genotype 46, XY

Has testis but phenotype is female

Inadequate testosterone synthesis due to 17 beta-hydroxysteroid dehydrogenase

Androgen insensitivity syndrome

5 alpha-reductive deficiency (no DHT)

Mutations in AMH or AMH receptor

28
Q

What is androgen insensitivity syndrome?

What happens at puberty?

What do these pts have a higher risk of developing?

A

Loss of functional androgen receptors (X-linked recessive); have testis but no spermatogenesis; testosterone levels may be high (neg feedback)

At puberty, testosterone is metabolized to estradiol initiating female secondary characteristics; pts have amenorrhea

Produce AMH so paramesonephric system is suppressed; no uterus or uterine tubes, short vagina

Testis found in inguinal of labial regions

Increased risk for tumor formation in gonads

29
Q

Where are the seminal vesicles, vas deferens, epididymus, and efferent ductules derived from?

Where is the prostate gland derived from and when?

Where is the bulbourethral gland derived form?

A

Buds from the mesonephric duct (intermediated mesoderm of the urogential ridge)

Buds form the endoderm of the UG sinus in the region of the pelvic urethra; week 10

Endodermal buds

30
Q

Derivatives of embryonic male and female reproductive structures:

  1. Indifferent gonad
  2. Primordial germ cell
  3. Somatic support cell
  4. Stromal cells
  5. Gubernaculum
  6. Mesonephric tubules
  7. Mesonephric duct
A
  1. Testis; ovary
  2. Spermatogonia; oocytes
  3. Sertoli cells; follicle cells
  4. Leydig cells; thecal cells
  5. Gubernaculum testis; round ligament of ovary and uterus
  6. Efferent ducts of testis, paradidymis; epoophoron, paroophoron
  7. Appendix of epididymus, vas deferens, seminal vesicle, ejaculatory duct; duct of epoophoron, gartner’s duct
31
Q

Derivatives of embryonic male and female reproductive structures:

  1. Paramesonephric duct
  2. Urogenital sinus
  3. Genital tubercle
  4. Urogenital folds, urogential plate, and glans plate
  5. Labioscrotal folds
A
  1. Appendix of testis, prostatic utricle; uterine tubes, uterus, vagina
  2. Prostatic and membranous urethra, prostatic gland, bulbourethral glands; membranous urethra, urethral/paraurethral glands, greater vestibular glands
  3. Glands penis, corpus cavernosum of penis, corpus spongiosum of penis; glands clitoris, corpus cavernosum of clitoris, bulbospongiosum of vestibule
  4. Penile urethral/ventral penis; Labia minora
  5. Scrotum; Labia majora
32
Q

What is 5 alpha-reductase deficiency?

A

46, XY genotype

Autosomal recessive

At birth: have male internal genitalia (testosterone) but ambiguous external genitalia; Normal testis and duct system; can make AMH and testosterone

Underdeveloped male external genitalia; may have external female phenotype

*At puberty: testosterone levels surge and cause masculinization and male external genitalia

33
Q

What are female DSDs?

What is the most common cause?

What mutations cause this?

A

46, XX genotype

Have ovaries;

Fetus produces excess androgens; masculinization of female external genitalia; labia may fuse to look like scrotum

Congenital adrenal hyperplasia: most common cause of female sexual ambiguity

Mutations in genes involving adrenocortical steroid biosynthesis (21 hydroxylase deficiency)

34
Q

What are ovotesticular disorders? (True intersexuality)

What causes this?

A

Have both testicular and ovarian tissue

Ambiguous external genitalia or mainly female; usually have uterus

Caused by translocation of piece of Y onto X (Barr body causes mosaicism); subset of cells may have a mutation in Y; anomaly in sex determination and differentiation of primordial germ cells

Endo/Repro Final (20 decks)

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