Early embryogenesis Flashcards

1
Q

What time period defines the pre-embryonic period?

A

From conception to 2 weeks

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2
Q

What time period defines the embryonic period?

A

2-8 weeks in utero

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3
Q

What time period defines the foetal period?

A

9 weeks to birth

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4
Q

What is fertilisation?

A

Fusion of sperm and egg

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5
Q

Fertilisation causes the beginning of the 2nd mitotic division what happens after this

A

The egg is activated by an influx of Ca2+ which causes the formation of the diploid chromosomes

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6
Q

What is the membrane surrounding the egg before implantation?

A

Zona pellucida

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7
Q

What occurs during cleavage?

A

Egg starts off with 2 cells (blastomere) to a multicellular stage in 3-4 days

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8
Q

What is the fate of the inner blastomeres of the morula?

A

They will become the inner cell mass

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9
Q

What is the fate of the outer blastomere of the morula?

A

They will become the outer cell mass

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10
Q

During cleavage water enters the cell what does this cause?

A

Water enters and pushes cells in the centre to 1 side forming a blastocyst

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11
Q

After the formation of the blastocyst what must occur for survival?

A

Implantation

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12
Q

Describe the events involved with early implantation

A

The outer cell mass of the blastocyst forms pillars that attach with the uterine stroma, the cells secrete enzymes and fuse with the uterine stroma

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13
Q

What 2 cell types from from the inner cell mass?

A

Epiblasts and hypoblasts

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14
Q

What is meant by the inner cell mass from a bilaminar?

A

Splits into 2 cell layers epiblast on the top, hypoblast on the bottom

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15
Q

What 2 cavities separate the outer and inner cell mass during late implantation?

A
Above = amnion
Below = primitive yolk sac
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16
Q

What is the cellular layer around the outer cell mass called?

A

Cytotrophoblast

17
Q

What is the acellular layer that surrounds the cytotrophoblast?

A

Syntio-trophoblast

18
Q

What is the function of the syntio-trophoblast?

A

Immune suppressive system to stop forgein matter being rejected