embryology Flashcards
define congenital
present at birth
define congenital disorders
birth defects
congenital disorders can be what?
- structural or functional
- condition present at or before birth
- genetic, infectious, nutritional and/or environmental in orgin
what are the periods in embryology?
- conceptus
- embryo
- fetus
What is the conceptus stage, and how long does it last?
The conceptus stage is from fertilization to the end of the 2nd week.
When does the embryo stage begin and end?
The embryo stage begins at the start of the 3rd week and ends at the end of the 8th week.
What is the time frame of the fetus stage in development?
The fetus stage begins in the 3rd month and continues until birth.
At what stage does organogenesis primarily occur?
Organogenesis primarily occurs during the embryo stage (3rd to 8th week).
Which stage marks the beginning of visible human form and growth?
The fetus stage (3rd month to birth).
What happens during Step 1: Ovulation?
A secondary oocyte is released from the ovary and swept into the oviduct
What occurs during Step 2: Fertilization?
A single sperm penetrates the secondary oocyte, and the sperm and egg nuclei fuse to form a zygote
What is the significance of Step 3: Cleavage?
The zygote undergoes rapid mitotic divisions, forming a pre-embryo that progresses through 2-cell, 4-cell, and 8-cell stages
What is formed in Step 4: Morula?
By day 4, successive divisions produce a morula, a solid ball of cells that enters the uterus.
What transformation occurs in Step 5: Blastocyst?
By day 6, the pre-embryo forms a blastocyst, a hollow ball of cells with a fluid-filled cavity. It frees itself from the zona pellucida and can increase in size.
What happens during Step 6: Implantation?
The blastocyst attaches to the uterine lining (endometrium) and begins to digest its way inward. Inner cell mass cells start forming the primary germ layers.
What is the role of the trophoblast in Step 5?
The trophoblast is the outer layer of the blastocyst that aids in implantation and interaction with the endometrium.
Where does fertilization typically occur?
Fertilization occurs in the oviduct.
What forms the inner cell mass, and what is its significance?
The inner cell mass is formed within the blastocyst and will develop into the embryo.
What is the duration of meiosis in the oocyte?
Meiosis in the oocyte is completed just before fertilization.
what is cavity formation?
facilitates cellular differentiation and organises embryonic structures
what is differentiation?
process where unspecialised to become specific
What are the two types of cells in a blastocyst?
The outer epithelial layer (trophoblast) and the inner cell mass
What is the role of the trophoblast in the blastocyst?
The trophoblast forms extraembryonic structures, including part of the placenta
What is the function of the inner cell mass in the blastocyst?
The inner cell mass gives rise to the embryo