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Foundations Of Medicine 1 > Embryology: Fertilisation To Trilaminar > Flashcards

Embryology: Fertilisation To Trilaminar Flashcards

1
Q

What is fertilisation

A

union of gametes - fusion of sperm and oocyte to form a zygote

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2
Q

Where does fertilisation take place

A

ampulla of the uterine tube

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3
Q

Fertilisation (1/4)

A

Sperm binds to zona pellucida glycoprotein

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4
Q

Fertilisation (2/4)

A

Acrosomal enzymes released from sperm head; sperm digests its way into egg

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5
Q

Fertilisation (3/4)

A

Egg and sperm plasma membranes fuse and sperm contents enters the egg

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6
Q

Fertilisation (4/4)

A

Sperm entry triggers completion of meiosis 2 and release of cortical granules by oocyte (make ZP impenetrable to other sperm)

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7
Q

What is cleavage

A

Zygote undergoes series of mitotic divisions that divide fertilised egg into blastomeres

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8
Q

What is a blastomere

A

one of the cells that are produced during cleavage of a zygote and that form the morula

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9
Q

Up to what stage are blastomeres thought to be totipotent

A

8 cell stage

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10
Q

What is a totipotent cell

A

Cells that can differentiate into any cell type including embryonic and placental cells

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11
Q

Mosaicism

A

Individuals with 2 or more cell line with different chromosome complements

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12
Q

When can mitotic nondisjunction occur

A

Early division of zygote

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13
Q

mitotic nondisjunction

A

The failure in mitosis for the two members of a chromosome pair to separate (to disjoin) normally, which causes both chromosomes to go to one daughter cell while none go to the other daughter cell

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14
Q

How many blastomeres in morula

A

16+

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15
Q

What does the inner cell mass of a blastocyst form

A

Embryo

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16
Q

What does the trophoblast of a blastocyst form

A

Feral placenta

17
Q

Blastocyst hatching

A

developing embryo (at around five days after fertilization) that is hatching out of the zona pellucida (ZP(Protective coating))

18
Q

On what day (number) does implantation typically occur

A

Day 6

19
Q

Where does implantation occur

A

Posterior or anterior uterine wall

20
Q

Ectopic pregnancy

A

implantation outside the uterus

21
Q

Placenta previa

A

placenta lies low in uterus and partially/completely covers cervix

22
Q

Development of the bilaminar embryo - day 7.5

A

Trophoblast divides into cytotrophoblast (individual cells) and syncytioblast (single multinucleated cell which produces hCG)

Embryobast divides into epiblast (dorsal surface) and hypoblast (ventral surface)

Amniotic cavity begins to form

23
Q

Development of the bilaminar embryo - day 9

A

amniotic cavity (epiblast) and primitive yolk sac (hypoblast) are formed

-Implantation complete

24
Q

Development of the bilaminar embryo - day 12

A

Uteroplacental circulation established

chorionic cavity is formed (Extraembryonic mesoderm develops then degenerates)

25
Q

Development of the bilaminar embryo - day 13

A
  • Further development of chorionic cavity
  • Presence of existing stalk (later umbilical cord)
  • Second wave of hypoblast cells migrate to form definitive yolk sac
26
Q

Development of the bilaminar embryo - Implanted embryo

A

Uteroplacental circulation forms

Amniotic cavity present above embryonic disc

Chorionic cavity developed and encircles embryo

27
Q

Implantation + location

A

Embryo implants into endometrial lining on posterior or anterior uterine wall

28
Q

Primitive streak features

A

-Primitive streak appears in midline at caudal end of epiblast

  • Cranial end of Primitive streak = Primitive Pit and Node
29
Q

Gastrulation

A

Invagination of the epiblast cells through the primitive stream to form the 3 primary germ layers

30
Q

What layers is the trilaminar embryo composed of

A

ectoderm, mesoderm, endoderm

31
Q

Fate of Epidermis

A
  • Epidermis of skin, hair, nails
  • Nervous system
32
Q

Fate of mesoderm

A

Paraxial mesoderm: axial skeleton, skeletal muscle
- Intermediate mesoderm: urogenital systems
- Lateral plate mesoderm
- Somatic layer: dermis, lining of body wall, parts of limbs
- Visceral layer: cardiovascular system, mesothelial covering of organs, smooth muscle

33
Q

Fate of endoderm

A
  • Lining of gut tube
  • Lining of respiratory tract
  • Lining of bladder and urethra

Foundations Of Medicine 1 (2 decks)

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