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Reproductive system > Lecture 4- Development of the reproductive tracts > Flashcards

Lecture 4- Development of the reproductive tracts Flashcards

1
Q

sexual differentiation involves the

A
  • gonads
  • genital ducts
  • external genitalia
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2
Q

during the first 5 weeks sexual development is

A

identical for both male (XY) and female (XX)

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3
Q

at week 5 the embryo is made up of

A

ectoderm

mesoderm

endoderm

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4
Q

mesoderm has 3 parts

A

paraxial- vertebral column

intermediate

lateral plate

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5
Q

intermediate mesoderm on both side of the embryo condenses into 2

A

cylindrical structures- urogenital ridges

  • runs parallel to the the future vertebral column
  • organises into a cylinder of mesoderm called the nephrogenic cord
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6
Q

nephrogenic cord goes onto become

A

urinary structures and the gonads

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7
Q

portion of the neohrogenic cord that gives rise to gonads in males and female

A

gential 9gonadal) ride

  • mesoderm covered in epithelium
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8
Q

gonadal development start

A

in the yolk sac covered in endoderm

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9
Q

gonads in the yolk sac are connecte dto the embryovia the

A

vitelline duct

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10
Q

some endoderm cells from the wall of the yolk sac differnetiate into

A

primordial germ cells

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11
Q

primordial germ cells in the yolk sac

A
  1. start to migrate along the vitelline duct
  2. eventually to the primitive digestive tract and later to the dorsal mesentery (sheet of tissue which anchors the digestive tract on the posteiror body wall)
  3. then they reach the genital ridge (week 6)
  4. primoridal germ cells settle in the epithelium
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12
Q

once at the epithelium in the genital ridge the primordial cells send out signals which

A

make them self organise into an undifferentiated gonad

  • can still develop into testes or ovaries
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13
Q

epitheilial layer of the undifferentiated gonad then forms

A

primitive sex cords- epithelial projections that penetrate inwards

  • mesoderm layer of gonad
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14
Q

what happens at around week 7

A

sex chromsookmes start expressing genes that cause gonadal differentiation

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15
Q

where on the chromosome is gondadal differentiation coded for in males

A

the Sex Determing Region of chromosome Y (SRY)

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16
Q

SRY codes for

A

testis determing factor

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17
Q

testis determing factor

A

intitiates development of testes

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18
Q

sex cords in the priordial testes become

A

medullary cords

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19
Q

medullary cords

A

grow loger nad carry the germ cells deeper into the mesoderm

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20
Q
A
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21
Q

in week 7 what happens to the surface epithelial layer of the gonad

A

thins out to become the tunica albuginea

22
Q

fter tunica albignea formation what happens to the meduallary cords

A

develop into 3 ductal stuctures inside the testes

  • seminiferous tubule
  • straight tubes
  • rete testes
23
Q

week 8 of teste formation after differentiation of medullary cord what happens to seminfierous tubule cells

A

some cells in the walls of the seminiferous tubule differentiate into sertoli cells

24
Q

sertoili cells surround the primodial cells and secrete ANTI-MULLERIAN HORMONE

A
25
Q

Week 8- cells inbetween seminiferous tubules differentitate into

A

leydig cells

26
Q

leydig cells

A

secrete testoterone

27
Q

anti-mullerian hormone and testosterone

A

masculinize the rest of the male reproductive systme

28
Q

in females there is no Y chromosome to s ecrete

A

Testes determining factor

  • gonads differentiate into ovaries
29
Q
A
30
Q
A
31
Q
A
32
Q
A
33
Q

what happens to the sex cords in the ovaries

A

degenerate

34
Q

what happens to the surface epithelium of the ovaries

A

proliferates and forms a second set of projections called cortical cords

35
Q

cortical cords rearrange to form

A

nests of follicular cells that surround the primordial germ cells

36
Q

primordial germ cell and follicular cell makes up

A

primordial ovarian follicle

37
Q

what happens inside the primordial ovarian follicle

A

primordial germ cell differentiates into the immature oocyte

  • halted in meosis 1 till puberty at which point they become secondary oocytes
38
Q

the rest of xx tract develops female characteristics due to

A

absence of testosterone

39
Q

genital ducts are originally

A

undifferentiated

40
Q

ducts present in undifferentiated embryo

A

mesonephric (wolffian)

paramesonephric duct (mullerian) - lateral to mesonephric duct

  • start in the thoracic and upper lumbar region
  • open into the urogenital sinus part of the cloaca
41
Q

mesonephric duct

A

wolffian duct- male reproductive system

42
Q

paramesonephric duct

A

mullerian duct- female reproductive system

43
Q

the urogenital sinus forms the

A

urinary tract

external genitalia

44
Q

development of male reproductive tract

A
  1. mullerian inhibiting factor amkes the mullerian duct degenerate into two bodies called the appendix testis
  2. Wolffian (mesonephric) duct grows long under the influence of testosterone- forming the reproductive ducts outside the testis
  3. efferent ductules connect the intratesticulaur straight tubules to the epididymis (where sperm mature)
  4. after the epididymis is the vas deferens through which sperm will be released during ejaculation
  5. seminal gland develops from each vas dferens (nourishing fluid for sperm)
  6. below the seminal glands is the ejaculatory duct which enters into the urogenital sinus which opens into the urethra
45
Q

development of female reproductive tract

A
  1. ovaires dont make testosteron- wolffian ducts degenerate
  2. ovaries also dont make mullerian inhibiting factor, so the mullerian (paramesonephric duct)
  3. 2 paramesonephric (mullerian) ducts form the 2 fallopian tubes
  4. in the lower region ducts fuse to form the uterovaginal primordium- tubular sturcture where the uterus, cervix and upper 1/3 of vagina develop
46
Q

lower 2/3 of vagina develops from the

A

urogenital sinus

47
Q

external sex organs also go through an

A

undifferentiated stage

48
Q

differentiation of the male external genitalia

A
  1. starts when testosteorne ekvekls starts to rise
  2. 5alpha-reducatse converts testosterone into dihydrotestosterone (more potent)
  3. at week 9 dihydrotestosterone masculinises the external genitalia
    • urethral folds fuse on the midline forming the penile urethra
    • primordial fallus lengthens and its tip forms the glans penis
    • body gives rise to the body of the penis- enlcoses penile urthrea
  4. labio-scrotum fuse as well giving rise to the scrotum
49
Q

differentiation of the female external genitalia

A
  1. abscence of testosterone
  2. urethral folds remain unfused and become the labia minora
  3. labioscrotal swellings become the labia majora (only fuse in anterior protion to give rise to the mons pubis
  4. primordial fallus shrinks and turns into the clitoris
  5. finished by week 12
50
Q

Descent of the testes

A
  1. intiially develop in the anteiror abdominal wall, anchored by the gubernaculum attached to the bottom of the scrotum
  2. gubernaculum starts to shorten pulling the testes down to the scortum via the inguinal canal
  3. inguinal canal forms a projection of the peritoneum called the processus vaginalis which herniates throguh the abdominal body wall
  4. by week 12 the testes meet the inguinal canal and move towards the scrotum
  5. on their way they pull the vas deferens and testicular artery and vein through the inguinal canal eventually forming the spermatic cord
  6. abdominal muscles that came along form the layers of the scrotum
51
Q

Descent of the ovaries

A
  1. also a gubernaculum that attaches the ovaries to the labia majora
  2. shortens to pull the ovaries down
  3. gubernaculum splits ionto the cranial and caudal parts
  4. when the uterus forms the middle of the gubernaculum attaches to it and separates into the cranial genital ligament (ovarian ligament) which anchors the ovaries slightly above and on either side of the uterus
  5. inferior portion of the gubernaculum= caudal genital ligament which becomes the round ligament

Reproductive system (28 decks)

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