Principles - Embryology 02 - Fertilisation to trilaminar Flashcards
Where exactly does fertilisation take place?
Ampulla of the uterine tube
Explain the steps involved in fertilisation of an oocyte by sperm.
Sperm binds to specific glycoprotein on the zona pellucida. Enzymes released from sperm head which breaks down zona pellucida, allowing it to enter. Oocyte and sperm membranes fuse. Sperm entry triggers Meiosis II and cortical granules are released by the oocyte to prevent more sperm from entering.
What is meant by ‘cleavage’?
Stage of rapid cell division resulting in an increase in the number of cells
What is meant by ‘compaction’?
Cells grow very tightly together within the zona pellucida. Fluid also enters ZP.
The part of the blastocyst which becomes the embryo is called….
Inner cell mass
The part of the blastocyst that becomes the placenta is called…
Trophoblast
Where is a desirable place for the embryo to implant?
Upper or middle dorsal wall
For the blastocyst to be able to implant, what process must first occur?
Hatching from the zona pellucida
State 3 abnormal implantation sites.
Any 3: Ovary, ampulla, uterine tube, lower part of uterus, cervix or peritoneum
The trophoblast divides into which 2 layers?
Cytotrophoblast & Syncytiotrophoblast
The embryo divides into which 2 layers during implantation?
Hypoblast and Epiblast
What is meant by gastrulation?
Movement of epiblast cells through the primitive streak to form the three primary germ layers
What is the fate of the ectoderm?
Becomes epidermis of the skin, CNS and PNS
Mesoderm becomes divided into which 3 regions?
Paraxial, Intermediate and Lateral Plate
Paraxial Mesoderm becomes…
Axial skeleton, voluntary muscles, part of dermis of skin
