Fertilisation, Cleavage and Implantation Flashcards

1
Q

What stage is the oocyte in when it is ovulated?

A

Metaphase of the second meiotic division

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2
Q

What surrounds the oocyte during ovulation?

A

Zona pellucida and some granulosa cells

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3
Q

How does the oocyte get from the ovary to the oviduct of the fallopian tube?

A

Fimbriae sweep the oocyte into the oviduct.

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4
Q

How does the oocyte move from the oviduct to the ampulla?

A

Peristaltic waves

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5
Q

How long does it take from the ovary to implantation in the uterus?

A

80 Hours

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6
Q

Draw an oocyte

A

in notes

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7
Q

Draw a spermatozoa

A

in notes

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8
Q

What is the role of the acrosome?

A

Helps penetrate the zona pellucida by releasing enzymes

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9
Q

What are the barriers to the sperm fertilising the egg?

A

Vaginal pH, Response of immune system, Cervical mucous and physical barriers e.g. condoms

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10
Q

What is fertilisation?

A

The process by which the male and female zygotes fuse

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11
Q

On average how long do spermatozoa retain their function in the female body?

A

72 hours

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12
Q

Where does fertilisation occur?

A

In the fallopian tube within 24 hours of ovulation

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13
Q

What is capacitation?

A

A 7 hour process where a glycoprotein coat and seminal plasma proteins are removed from the spermatozoa head

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14
Q

Why is capacitation important?

A

Only capacitated sperm can pass through corona cell and undergo acrosome reaction

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15
Q

Describe stage 1 of fertilization

A

Penetration of corona radiata. Capacitated cells pass straight through.

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16
Q

Describe stage 2 of fertilization

A

Penetration of zona pellucida.

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17
Q

What is the zona pellucida made up of?

A

Glycoproteins

18
Q

What is the function of the zona pellucida?

A

Facilitates and maintains cell binding + induces the acrosome reaction

19
Q

Describe stage 3 of fertilization

A

Cortical and Zona reactions. Cortical granules release hydrolytic enzymes which cleaves ZP2 and modifies ZP3 which means no more sperm can bind

20
Q

What is important about cortical granules

A

They release hydrolytic enzymes which prevents polyspermy

21
Q

Describe stage 4 of fertilization

A

Fusion of membranes and resumption of 2nd meiotic division - head and tail of sperm enter but plasma membrane left behind.

22
Q

Describe oogenesis and follicle development

A

In notes just look at them

23
Q

Describe stage 5 of fertilization

A

Formation of male and female pronuclei. They contain 23 chromosomes each. The membranes break down and the chromosomes are arranged for mitosis

24
Q

What is cleavage

A

A series of mitotic divisions.

25
Q

Describe cleavage

A

The blastomere divides until it is a 16 cell morula which undergoes compaction to become a blastocyst

26
Q

What is implanted into the uterus?

A

The blastocyst

27
Q

Label the blastocyst

A

in notes

28
Q

What does the outer cell mass of the blastocyst become?

A

The trophoblast

29
Q

What phase of menstruation are females in at the time of implantation?

A

Secretory

30
Q

Where does the blastocyst implant?

A

The endometrium

31
Q

What are the stages of menstruation?

A

Menstruation, proliferation, secretion, implantation window (would be menstruation if no fertilisation occurs)

32
Q

What does the trophoblast differentiate into?

A

Syncytiotrophoblast and Cytotrophoblast

33
Q

What happens to the uterine mucosa?

A

It reacts to the implantation by the decidual reaction. The ST phagocytose the decidual cells and erode capillaries.

34
Q

What does the ST do?

A

It produces lytic acid and secretes factors that cause apoptosis of endometrial epithelial cells.

35
Q

What happens in the middle of week 2

A

Lacunae appear in ST, which fill with blood. The ST stops in the zona compacta

36
Q

What happens on day 13

A

Primitive uteroplacental circulatory system arises

37
Q

Which way round are the amniotic cavity and umbilical vesicle?

A

Amniotic cavity - Dorsal and umbilical vesicle - Ventral.

38
Q

What forms the floor of the amniotic cavity and roof of the umbilical vesicle

A

The epiblast - Floor, Hypoblast - roof

39
Q

What are 3 parent babies for?

A

Mitochondrial diseases

40
Q

What does a 3 parent baby mean?

A

Genes of parent are inserted into the egg of the donor, the the donors are removes but the functional mitochondria is left.