Embryology Flashcards
The first two weeks of prenatal development is known as the
Pre-embryonic period
How do you define the foetal period?
From week 9 of development until birth
A fertilised ovum is known as a
Zygote
The specialised extracellular matrix that surrounds the developing oocyte is known as the
Zona pellucida
List some of the functions of the Zona pellucida
- Provides nutritional and mechanical support to the oocyte
- Helps in binding of sperm
- Protmotes acrosomal reaction
- Prevents polyspermy
List the four outcomes of fertilisation:
- Restores normal diploid number of chromosomes (46)
- Secondary oocyte completes meiosis
- The sex of the embryo is established
- Initiation of cell division (cleavage)
The rapid mitotic division of cells in a zygote is known as
Cleavage
What is the outcome of “cleavage?”
- Zygote undergoes rapid cell divisions with no overall growth, producing a cluster of cells.
- Different cells derived as a result of cleavage are called blastomeres
- Result is a compact mass/ball of cells called a morula
When is the “embryonic period?”
Weeks 3-8
What is the significance of the embryonic period?
Most of the organ systems are developed
What are the normal sites of implantation of the embryo?
The fundus of the uterus, posterior wall of the uterus, sometimes the side walls
What is the outcome of implantation of the embryo in the fallopian tubes?
Ectopic pregnancy
What are the names of the three major germ layers in an embryo?
Endoderm, mesoderm, ectoderm