Repro- Embryology Flashcards

1
Q

What is embryogenesis

A

the first 8 weeks of embyro development after fertilisation

day 5 - blastocyte
week 2-3 - bilaminar disc
week 3-4 - trilaminar (3 germ layers)
week 5-8 - organoenesis

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2
Q

When does the fertilised egg form a blastocyst?

A

day 5

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3
Q

How is the blastocyst organised?

A

Two cell groups

  1. inner cell mass - embyroblast (develop to form baby)
  2. trophoblast (develops to form the placenta)
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4
Q

What does the inner cell mass of the blastocyst become?

A

Bilaminar disc (columnar epithelial cells - epiblast) and hypoblast cells

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5
Q

What are the two layers of the bilaminar disc called?

A

Epiblast -> (becomes 3 germ layers after gastrulation)

Hypoblast -> (becomes extraembryonic mesoderm)

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6
Q

cytotrophoblasts (outer cells of trophoblast) for what?

A

Chorionic villi (invades endometrium during implantation)

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7
Q

The inner cell mass of blastocyst differientiates into the bilaminar disc

a. true
b. false

A

a. true

  • epiblasts
  • hypoblasts
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8
Q

Two cavities form either side of the bilaminar disc, what are they called?

A

cytotrophoblasts/syncytiotrophoblasts cells (form placenta)

Epiblast cells
Hypoblast cells
——————
Yok Sac

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9
Q

the inner cell mass of blastocyt forms the bilaminar disc

a. true
b. false

A

a. true

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10
Q

what do epiblast cells differieniate into?

A

3 germ layers via gastrulation (trilaminar disc)

(begins with primitive streak appearing in the caudal end of the epiblast).

through this streak, cells migrate to form the
1. endoderm (displace hypoblasts)
2. mesoderm
3. remaining epiblast cells (ectoderm) do not migrate

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11
Q

Ectoderm forms?

A

CNS, PNS, neuroendocrine organs , (adrenal medulla, pituitary gland)

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12
Q

Which part of the mesoderm form the kidneys, utreter and gonads?

A

intermediate mesoderm

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13
Q

How are diyzgotic twins formed?

A

two or more eggs are fertilised

and implanted

non-identical - genetically distinct

more common

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14
Q

How are monozygotic twins formed?

A

1 embyro is split!!

identical twins

splitting of embryo determines nature of the pregnancy

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15
Q

What does dichorionic diamniotic mean?

how does it occur

A

have a seperate placenta and seperate amniotic sac

THE EARLY EMBRYO SPLITS before implanting in the womb

20% of monozygotic twins

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16
Q

What does monochorionic diamniotic mean?

how does it occur?

A

Share placenta and have seperate amniotic sac

Early embyro implants in the womb and then splits

75% of monozygotic twins

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17
Q

What does monochorionic monoamniotic sacs?

A

Share placenta and share amniotic sac

Early embyro implants in the womb and then splits LATER ON (the later splits after implantation - the more likely to share both)

5% of monozygotic twins - BOTH are shared - high risk

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18
Q

The inner cell mass of the blastocyst called the embyroblast goes through differientation into a bilaminar disc followed by a trilaminar disc through a process callled?

A

gastrulation

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19
Q

beyond 8 weeks the embyronic period ends and the fetal period begins

a.true
b. false

A

a. true

embyrogenesis is the 1st eight weeks of embyro development post fertilisation

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20
Q

Reproductive and renal systems have a common origin and develop from the ?

A

intermediate mesoderm

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21
Q

The intermediate mesoderm develops into

A

urogenital ridge

which develops into

  1. nephrogenic cord (laterally)-> kidney/ureters
  2. gonadal ridge (medially)-> gonads
22
Q

Horseshoe kidney

A

fused kidney

23
Q

duplex kidney

A

two kidneys at one side

24
Q

pelvic kidney

A

kidney not ascended from pelvis during development

25
The caudal end of the yok sac develops into
the cloaca
26
the cloaca is divided by the urorectal septum to form
1. urogential sinus -> bladder/urethra 2. anal canal -> rectum and hindgut
27
What region of the Y chromosome determines sex
SRY gene (SYR gene produces testes determining factor - SRY protein) SRY protein produces the testis protein acts on indifferent gonad to promote the formation of the testes
28
cryptorchidism
undescended testicle
29
what develops from the nephrogenic cord
kidney and ureter
30
what develops from the urogenital part of the cloaca
bladder and urethra
31
urinary system and gonads have a common origin?
urogenital ridge of the intermediate mesoderm
32
gonads develop from the gonadal ridge a. true b. false
a. true
33
Differientiation into testis or ovary is dictated by the presence of Y chromosome and AMH a. true b. false
a. True Anti-Mullerian hormone - The AMH gene provides instructions for making a protein that is involved in male sex differentiation. During development of male fetuses, the AMH protein is produced and released (secreted) by cells of the testes.
34
There are two sets of genital ducts? which are undifferentiated in the embyro
1. mesonephric duct 2. paramesonephric duct (female duct development) in men - AMH causes Mesonephric to continue to develop (M for Men)
35
the mesonephric duct forms the epididymis , vas deferns and seminal vesicles in men a. true b. false
a. true under effect of testosterone
36
in women the paramesonephric duct continues to develop and the mesonephric duct regresses a. true b. false
a. true in the absence of AMH ducts grow medially and fuse -> canalise to form uterus and upper 2/3 vagina
37
urogential folds form what in 1. male 2. female
1. spongy urethra in men 2. labia minora
38
genital tubercle forms what in 1. female 2. male
1.clitorus 2. penis
39
labioscrotal swelling forms what in 1. men 2. women
1. scrotum 2. labia majora
40
what causes a micro-penis?
genital tubercle does not elongate fully
41
crytochordism
undescended testicle
42
absence of the vas deferens is common in what disease?
cystic fibrosis
43
if the paramesonephric duct doesnt develop - there will be uterine agenesis a. true b. false
a. true underdevelopment or absence uterus
44
why might uterine not develop
1. paramesonephric ducts dont develop or are underdeveloped 2. ducts do not fuse in the middle 3. ducts fuse but do not undergo cannalisation (stay as band instead)
45
a rare congenital condition where the hymen membrane doesn't develop properly in the fetus, blocking the vaginal opening
imperforate hymen
46
AMH in males causes the paramesonephric ducts to regress a. true b. false
a. true
47
In males, paramesonephric duct develops under the effect of testosterone to form the epididymis, vas deferens and seminal vesicles a. true b. false
b. false the mesonephric duct!! - wolffian
48
In females, the paramesonephric duct fuse to form the uterus, upper 2/3 vagina a. true b. false
a. true | lower 2/3 vagina is formed from the urogenital sinus
49
What 3 structures form the male and female external genitilia
1. genital tubercle 2. urogenital folds 3. labioscrotal swelling
50
Reproductive tract abnormalities are associted with renal abnormalities a. true b. false
a. true they can be due to common origin of intermediate mesoderm
51