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Endo Test 2 > Embryology > Flashcards

Embryology Flashcards

1
Q

Where do the urinary and internal repro organs develop from?

A

intermediate mesoderm

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2
Q

What determines the male development?

A

The Y chromosome has the SRY gene - the protein product of this gene is TDF which masculiizes the indifferent genital system by causing testes development.
- testes develop and secrete testosterone which results in further masculinzation

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3
Q

What do sertoli cells?

A

MIF - result in paramesonephric duct’s regression

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4
Q

What do Leydig cells do?

A

secrete testosterone, which results in formation of DHT

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5
Q

What does testosterone do?

A
  • secreted from Leydig cells
  • transforms mesonephric duct and mesonephric tubules into male genitalia ducts and glands
  • development of efferent ductules, epidymis, ductus deferens, seminal vesicle and ejaculatory duct
  • MASCULINIZES GENITALIA
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6
Q

What does DHT do?

A

determines hormonal sex

- development of UG sinus/indifferent genitalia to penis, scrotum, prostate gland, prostatic urethra and penile urethra

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7
Q

What is the indifferent stage?

A
  • genital (gonadal) ridges form from intermediate mesoderm
  • epithelium (cortex) grows into underlying mesoderm to form primitive sex cords (medulla)
  • Primitive germ cells migrate to genital ridges week 4-6. If PGC’s don’t migrate, then gonads will not form
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8
Q

What does TDF do?

A

TDF induces the indifferent gonad to form testes

  1. Medulla of primary gonad will form testes (the primitive sex cords will remain as solid tubes until canalization at puberty, where they will form SF tubules, rete testes). Testes start to secrete testosterone at week 8.
  2. Cortex of primitive gonad will form tunica albuginea
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9
Q

What controls descent of testes?

A

Testosterone

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10
Q

what is the gubernaculum?

A

thick ligament that attaches the caudal pole of the testes to the anterior body wall (future site of deep inguinal ring) - aids in descent of gonads

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11
Q

What is the processus vaginalis?

A

an evagination of peritoneum that passes through the abdominal wall lateral to the site of attachement of the gubernaculum

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12
Q

How do the testes descend?

A
  • the processus vaginalis and gubernaculum (and thus testes and ductus deferens) are pulled through the abdominal wall, forming the inguinal canal
  • The proximal portion of the processus vaginalis closes (closes around deep inguinal ring, if not closed can lead to indirect hernia); the distal portion form tunica vaginalis around testes
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13
Q

What is the indifferent stage?

A
  • two duct systems are formed from intermediate mesoderm
    1. Mesonephric (Wolffian ducts): mostly contribute to male ducts - form internal genitalia
    2. Paramesonephric (Mullerian) ducts: mostly contribute to femal ducts
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14
Q

What does Antimullerian hormone do?

A

AMH is secreted by sertoli cells

- will inhibit the formation of the paramesonephric ducts, and prevent development of femal genital ducts

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15
Q

What do male mesonephric tubules turn into?

A

efferent ductules, appendix and epididymis

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16
Q

What do mesonephric ducts turn into?

A

epididymis, ductus deferens, ejaculatory duct, seminal vesicle

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17
Q

What does urethra in males give rise to?

A

prostate and bulbourethral glands

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18
Q

What happens with paramesonephric duct in males?

A

it regresses except for the appendix of the testes and prostatic utricle

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19
Q

What happens with cloacal folds of indifferent stage in males?

A

The cloacal folds are mesenchymal swellings around the cloacal membrane

  • they will divide into urethral and anal folds
  • they will anteriorly fuse to form the genital tubercle
  • when testosterone and DHT are produced around 12 weeks, they will continue to grow into the penis.
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20
Q

What forms the anus?

A

anal folds

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21
Q

what forms the glans penis?

A

genital tubercle

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22
Q

what forms the shaft, root of penis and penile urethra?

A

urethral folds

  • the elongate along with the genital tubercle.
  • the urethral groove is an open grove on the ventral penis
  • the two urethral folds with fuse to form the penile urethra
  • the remaining portion of the urethra (in the glans penis) is formed by ectodermal cells that grow inward.
23
Q

what froms the scrotum?

A

Labioscrotal swellings

- scrotal septum forms where the two swellings fuse

24
Q

hypospadias

A
  • caused by incomplete fusion of the urethral groove on ventral surface of penis.
  • abnormal opening of penile urethra on ventrl surface of penis
  • DEPENDENT ON TESTOSTERONE
25
Q

Epispadias

A
  • urethral opening is on dorsum of penis
  • often occurs with exstrophy of the bladder
  • thought to be due to urethral plate developing more dorsally than normal
    TESTOSTERONE DEPENDENT
26
Q

Congenital indirect inguinal hernia

A

cause: proximal processus vaginalis remains patent
- intestinal loops pass through the open passageway
- more common in males

27
Q

Hydrocele

A

Fluid filled sac around scrotum or spermatic cord

- cause: excessive serous fluid f=production

28
Q

cryptorchidism

A
  • failure of testes to descend into scrotum
    TESTOSTERONE DEPENDENT
    undescended testes will be infertile due to temperature dysregulation
  • one of the biggest risk factors of testicular cancer
29
Q

what does absence of TDF induce?

A
  • indifferent gonad to form the ovary
  • sex cords in medulla degenerate
  • second generation of cortical sex cords form from the epithelium; these form the follicular cells around the oogonia
  • Cortex forms ovary; medullar regresses
30
Q

what does female gubernaculum form?

A

forms the ovarian ligament and round ligament of the uterus

31
Q

what will processus vaginalis form in female?

A

very small, obliterates before birth

32
Q

female mesonephric duct?

A

mostly regresses

33
Q

female paramesonephric duct?

A

mostly contributes to female ducts

  • cranial end opens into abdominal cavity to form tubes
  • caudal end fuse and enters cloaca to form body of uterus
34
Q

What does absence of AMH result in?

A

no testosterone production.

  • allows paramesonephric ducts to differentiate into female genital ducts.
  • mesonephric ducts degenerate in absence of testosterone
35
Q

what forms the uterine tube

A

cranial end of paramesonephric duct

36
Q

what forms the uterus, cervix, superior vagina?

A

caudal fused portion of the paramesonephric ducts

37
Q

what forms the inferior portion of the vagina?

A

sinovaginal bulb (vaginal plate)

  • forms from the urogenital portion of the cloaca - induced by the paramesonephric ducts.
  • initally forms a solid tube called the vaginal plate which canalizes by 5th months
  • forms the hymen
  • urethral endoderm will give rise to greater vestibular and skene’s gland
38
Q

what forms the clitoris?

A

genital tubercle

39
Q

what forms labia minora

A

urethral folds

- urethral groove remains unfused and will form the vestibule

40
Q

what forms labia majora

A

labioscrotal swellings.

41
Q

uterus arcuatus

A

slight lack of fusion of paramesonephric ducts: slight indentation seen at fundus of uterus

42
Q

uterus didelphys

A

double uterus with double vagina

  • complete lack of fusion of paramesonephric ducts and formation of two sinovaginal bulbs
  • most extreme!
43
Q

uterus bicornis (bicollis)

A

partial lack of fusion of paramesonephric ducts

- see two uteruses, but one vagina

44
Q

uterus unicornis

A

complete agenesis of one paramesonephric duct

45
Q

vaginal and cervical atresia

A

atresia of the sinovaginal bulbs or failure of canalization

46
Q

remanants of mesonephric tubules and ducts?

A
  • epoophoron (tubules)
  • paroophoron (tubules and duct)
  • gartner’s duct: remant of caudal mesonephric duct
  • ** all of the above can become cystic
47
Q

klinefelter syndrome

A

cause: nondisjunction during meiosis
47, XXY; male
- infertile due to low levels of testosterone; aspermatogenesis
- impaired sexual maturation
- gynecomastia
- external genitalia is male; but at puberty don’t develop secondary male characteristics
- high levels of estrogen results in more female secondary sex characteristics.

48
Q

Turner syndrome

A

45 XO

cause: nondisjunction during meiosis
- ovaries don’t form, testes don’t form
- gonadal dysgensis occurs and there is streak gonads (persistent genital ridge)
- lack of secondary sex characteristics at puberty
- short stature, broad chest, short neck, lymphadema of hands and feet

49
Q

Swyer syndrome

A

46 XY
Cause: point mutation of SRY gene results in defective TDF production
- gonadal dysgenesis occurs and streak gonads develop. Thes gonads can become cancerous and are often removed before puberty
- female external and internal genitalia (except for ovaries)
- amenorrhea
- lack of secondary sex trait characteristics because no ovaries = no estrogen

50
Q

True hermaphroditism

A

extremely rare!
- presence of male and femal gonadal tissue
“ovatestes” - ovarian and testes tissue found in same gonad
- most have 46, XX
- cause is due to translocation of portion of Y containing SRY gene onto X
- ambiguous external genitalia

51
Q

female psuedohermaphroditism

A

46, XX –> has ovaries

  • external genitalia is opposite of genotype
    cause: congenital adrenal hyperplasia (excessive production of androgens by adrenal glands)
  • internal reproductive organs are female
  • masculinization of external genitalia due to hyperactive corted secreteing testosterone which causes vaginal plate to regress and enlarged clitoris that looks like a penis
52
Q

male psudohermaphroditism

A

46, XY

  • phenotypically female
  • testes form due to normal functioning Y chromosome
  • insufficient androgen production and AMH results in hypogonadism
  • external and internally genitalia is female
53
Q

androgen insenstitivy syndrome

A

46 XY

  • has testes due to normal functioning Y chromosome
  • AMH and testosterone production is normal
  • lack androgen receptors on the tissues - they tissues are not responsive to testosterone
  • mesonephric duct degernerates due to insensitivity to testosterone
  • paramesonephric duct degenerates as well because of AMH
  • have female external genitalia; including secondary sex traits
  • vagina is short and blind-ending
  • no internal genitalia besides undescended testicles

Endo Test 2 (10 decks)

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