Embryo development Flashcards
What sperm protein activates the oocyte?
Phospholipase C zeta
What happens during activation of the oocyte?
It releases calcium from internal stores and this facilitates fertilization
What is the term for when male and female chromosomes pair at the centre of the cell?
Syngamy
What occurs during day 2-3 of embryo development?
Cleavage- divisions of the cells
What occurs during day 4 of embryo development?
Compaction
What happens during compaction of the embryo?
Cells flatten and maximise intracellular contacts. Tight junctions form.
What happens during day 5 of embro development?
Cavitation and differentiation
What happens during days 5-6 of embryo development?
Expansion
What happens during expansion of the embryo?
The fluid filled cavity at the centre expands, diameter increases, the zona pellucida thins
When does hatching of the embryo occur?
Day 6+
What layer does the embryo hatch through?
Zona pellucida
On what day does cellular differentiation occur?
Day 10
What are the phases of embryo implantation?
Apposition, attachment, invasion, decidual reaction, maternal recognition
What is apposition?
Unstable adhesion of the blastocyst to the uterine lining
What is attachment?
Stable adhesion of the blastocyst to the uterine lining
What is invasion?
When the trophoblast protrusions penetrate the endometrium and cells change to syncytiotrophoblast
What is the decidual reaction?
Progesterone primed endometrial stromal cells adjacent to the blastocyst differentiate into decidual cells and secrete growth factors to support the embryo before the placenta is fully developed
What occurs to allow for maternal recognition?
Leukocytes in the endometrial stroma secrete interleukin-2 which prevents maternal recognition of the embryo as a foreign body
What is capacitation?
Reorganisation of the sperm cell membrane, resulting in the tail movement changing to propel the sperm forward
What prevents multiple sperm entering the oocyte?
Influx of calcium in the oocyte causes the egg cell membrane to depolarise to prevent polyspermy
What is the acrosome reaction?
Exocytosis of the acrosome to release the acrosomal contents of the sperm and exposing the inner acrosomal membrane proteins
