Pre-implantation Embryo/ Development Implantation

Question 1

What sperm protein triggers oocyte activation

Answer 1

Phospholipase C zeta

Question 2

Describe the role of Ca in fertilisation

Answer 2

Oocyte activation activates the egg to release calcium from internal stores and this rise in Ca facilitates fertilisation

Question 3

Prior to day 4-8 cell stage the development control depends on

Answer 3

Maternally derived stores of RNA laid down during oogenesis

Question 4

What is the genetic control occurs in a 4-8 cell embryo

Answer 4

Activation of the embryonic genome and start of embryonic transcription

Question 5

Define totipotent in regards to blastomeres

Answer 5

The nuclei of individual blastomeres are each capable of forming an entire foetus

Question 6

How many cells are in a morula

Answer 6

Around 16

Question 7

What forms the placenta

Answer 7

Trophectoderm

Question 8

How does metabolic and biosynthetic activity differ in early cleavage vs blastocyst

Answer 8

Low in early cleavage

High in blastocyst

Question 9

Where does the embryo get nutrients from

Answer 9

Cumulus cells
Fallopian tube secretions - Ca, Na
Uterine secretions - Fe, glucose

Question 10

What factor enhances embryo-endo interaction

Answer 10

Leukaemia inhibitory factor

Question 11

Give 3 ways the uterus changes for implantation.

Answer 11

Endometrial cell changes to he,o absorption of uterine fluid - bring blastocyst nearer to the endometrium and immobilises it

Changes in thickness of endometrium and its blood supply development

Formation of decidua

Question 12

Which substances mediate the cross talk between endometrium and the developing embryo

Answer 12

Sex hormones
Cell adhesion molecules
Proteases
Cytokines, growth factor

Question 13

Describe the apposition stage of embryo implantation

Answer 13

Unstable adhesion of the blastocyst to the uterine lining
Synchronisation of embryo and endometrium
Hatched blastocysts predicated via embryonic pole - always attaches at area above inner cell mass

Question 14

What promotes placental formation

Answer 14

Decidual reaction

Question 15

Describe What differentiates into decidual cells

Answer 15

Stromal cells adjacent to the blastocyst differentiate into metabolically active decidual cells under the influence of progesterone

Question 16

What is the role of progesterone

Answer 16

Stimulates stromal oedema and secretory activity
Modifies distribution of oestrogen receptors
Increases volume of blood vessels
Stabilises lysosomes

Question 17

What prevents maternal recognition of the embryo ad a foreign body

Answer 17

Leukocytes in the endometrial stroma secrete interleukin-2 during the early stages of implantation

Question 18

Where are a) human chorionic gonadotropin- alpha and b) hCG-b synthesised

Answer 18

A) cytotrophoblast cells

B) syncytiotrophoblast cells of placenta

Question 19

Rising levels of……… from day 7-8 signify onset of implantation

Answer 19

hCG-b levels

Question 20

What are some roles of hCG

Answer 20

ensures the corpus luteum continues to produce progesterone throughout the first trimester of pregnancy - prevents menstruation

Interact with endometrium via specific receptors

Immunosuppressive- highly negative charge which may repel immune cells of mother and protect foetus