Conception And Fetal Development Flashcards
Conception occurs in the…
Ampulla of the Fallopian tubes (not uterus)
Conception
Union of eggs and sperm and marks the beginning of pregnancy.
Ovum comes from….
The grafting follicle at ovulation
Two protective layers of the ovum
Zona Pellucida
Corona Radiata
Zona Pellucida
Thick shapeless membrane that covers the ovum
Corona Radiata
Outer ring composed of elongated cells that are held together by hyaluronic acid
What chance of conception is there with a healthy cycle and good variables?
25%
Length of time it takes sperm to reach ovum and how long they are viable for
4-6 hours
72 hours
What is capacitation
When the sperm is exposed to the reproductive tract and it’s protective coating on the acrosome (head) comes off. Enzymes escape and the enzymes are necessary for sperm to penetrate the egg
What is the Zona Reaction ?
When an egg is penetrated by one sperm, another will not be able to fertilize it and the egg will degenerate if it happens
What is a pronuclei?
When the nucleus of the spermatozoa and ovum become distinct bodies of chromatin (chromosomes)
What is the name of the structure with 46 chromosomes
Zygote
What are the three main events of the pre embryonic period?
Divisions of cells
Implantation
Development of fetal membranes
How many times does the zygote divide?
Until 64 cells are produced
At what number cell stage does the zygote enter the uterus?
16 cells stage (morula)
What is a morula?
A 16 cell stage surrounded by a Zona Pellucida
What has to happen before a zygote embeds?
Divide into a blastocyst
What happens during implantation?
The Zona Pellucida degenerates
Structural changes occur
Fluid in the center pushes cells to the outside border
The inner cell mass (blastocyst) becomes the embryo and embryonic membranes
What is the outer cell mass of the embryo called and what is its principle function?
Trophoblast- eventually become the chorion
To secure food for the embryo and embed the ovum
Where is the ovum usually implanted
Upper part of uterine wall
What are chronic villi
Finger like projections that develop out of trophoblasts into the endometrium
Why are chronic villi important
They contain blood vessels that get O2 and nutrients from moms blood and dispose of waste
They also secrete Hgc hormone