Embryology Flashcards

1
Q

When does meiosis 1 of the oogonium occur?

A

During foetal stage

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2
Q

When does meiosis 2 occur?

A

Adolescence

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3
Q

What does fertilisation produce?

A

A zygote

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4
Q

What is the process of fertilisation?

A

100s of sperm surround the egg (ovum) but only 1 will penetrate

(pro) nucleus of the sperm enters and fuses with the (pro) nucleus of ovum to give a diploid cell (zygote)

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5
Q

What happens in week one (pre-embryonic phase)?

A

Zygote divides to form a blastocyst.

Moves through uterine tube to reach uterine cavity.

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6
Q

What does a zygote develop into next?

A

Morula via mitosis

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7
Q

What is a morula?

A

A solid ball of cells

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8
Q

What does a morula develop into next and why?

A

Blastocyte

Due to being a solid mass of cells, central cells cannot get enough nutrients from diffusion so cell reforms.

Forms a blastocystic cavity where cells accumulate at one end to form an inner cell mass and an outer lining of cells called the trophoblast.

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9
Q

What are the parts of a blastocyte?

A

Trophoblast
Inner cell mass
Blastocyte cavity

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10
Q

When does implantation occur and what starts to form?

A

Day 6

Placenta begins to develop
- sacs, membranes and cord to nourish the human conceptus (baby) start to form.

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11
Q

What is formed after a blastocyst?

A

Trophoblast

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12
Q

What does a trophoblast develop into next and how?

A

Continues to divide and develop finger like processes called chronic villi

Chorion

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13
Q

What does a chorion do?

A

Implants into the uterine wall
- Finger like processes help it bury into the uterine wall
Forms part of the placenta (eventually)
Secretes HCG hormone

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14
Q

What does the HCG hormone show?

A

Excreted in urine and used to detect pregnancy

The hormone stops the endometrium from shedding every month

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15
Q

What happens to the inner cell mass in the chorion?

A

Flattens itself to form a bilaminar disc
2 layers:
- Epiblast
- Hypoblast
2 cavities:
- Amniotic cavity
- Yolk sac

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16
Q

What are the main functions of the placenta?

A

Foetal nutrition
Transport of waste and gases
Immune etc

17
Q

What is the placenta made up of?

A

Foetal part and surface
- Smooth with foetal blood vessels and end of umbilical cord
Maternal part
- Decidua basalis of endometrium
- Rough and has maternal blood vessels

18
Q

What development occurs in week 3? (4)

A

Formation of germ layers - GATRULATION
Formation of neural tube - NEURULAISATION
Development of somite’s
Early development of CVS