Fertilisation

Question 1

Secondary oocyte?

Answer 1

Occurs 1 day before ovulation.

Finishes meosis 1- 1st polar body.

Begins meiosis 2 and arrests at metaphase until fertilisation.

Question 2

What 6 things do sperm bring to the ovum?

Answer 2

1. DNA
2. Centrosome
3. Sperm factor
4. Mitochondria
5. RNA
6. Calcium

Question 3

Why is calcium important component the sperm brings to the ovum?

Answer 3

Allows the oocyte to finish meiosis 2

Question 4

Name the 2 roles of calcium elevation?

Answer 4

1. Block to polyspermy
2. Triggers meiotic resumption

Question 5

How does calcium block polyspermy?

Answer 5

Permeability of the zona pellucida changes when the head of the sperm comes in contact with the oocyte surface.

Release of lysosomal enzymes from certical granules.

Alter properties of the zona pellucida.

Prevent sperm pentration.

Question 6

How does calcium trigger meiotic resumption?

Answer 6

Sperm fuses with oocyte arrested in meiosis 2.

Calcium triggers the release of the second polar body.

Initiates activation of development.

A series of waves of calcium is needed to trigger resumption.

Question 7

How can it be determined which cell is the polar body (after cleavage)

Answer 7

The polar body recieves hardly any cytoplasm.

Question 8

Female pronucleus?

Answer 8

Chromosomes (22+X) arrange themselves in a vesicular nucleus

Question 9

Phospholipase C zeta?

Answer 9

Only detected in the testes.

Preset in whole sperm.

This is the sperm factor that activates the calcuim influx in ovum.

Evidence: defects in PLCε shows male infertility

Question 10

What happens with the spermatozoan reaches the inside of the ovum

Answer 10

See additional sheet 17

Question 11

How is an egg selected to be IVF?

Answer 11

The objective is to select the best quality egg for transfer.

Non-invasively- do not harm the egg.

Question 12

Name a couple of meta anaylsis on the egg quality.

Answer 12

1. Cumulus oocyte complex.
2. Zona pellucida
3. Morphology of the first polar body.

Question 13

Define the cumulus cells?

Answer 13

Specialised granulosa cells surrounding and noursihing the oocyte.

Stripped off the egg during IVF.

a mass of follicular cells surrounding the oocyte in the vesicular ovarian follicle.

Question 14

What are you looking for when you are screening the embryo?

5 distinct compounds.

Answer 14

The timing and the symetry of the following.

1. Normal morphology
2. Early cleavage.
3. Amino acid turnover.
4. Metabolomic profiling.
5. Blastocyst development and transfer

Question 15

Normal morphology?

Answer 15

Grading the embryo on a variety of days to what it looks like.

Symmetry

No. cells at each stage

Question 16

Early cleaving embryos?

Answer 16

Watch the zygote develop.

Select the ones that are developing well (ie. after 27 hrs should be 2 cells- removes the ones that are not).

Question 17

Amino acid turnover?

Answer 17

The embryos with the lower metabolism are better.

Higher metabolism signifys there is a lot of damage and the zygote has to repair a lot

Question 18

When is the blastocyst formed?

Answer 18

Late day 4-Day 5.

Question 19

What two phases has to be complete for the blastocyst to form?

Answer 19

Compaction (cells becoming indistinct)

Blastulation: Blastocoel forms through filling with fluid