Embryogenesis Flashcards
How many chromosomes and chromatid are found in the spermatozoon (sperm) and ovum (egg)?
1N, 1C
1 copy each chromosome, 1 chromatid for each chromosome
How many chromosomes and chromatids are found in the zygote?
2N, 2C
After DNA synthesis in the zygote what changed?
There are 2 pronuclei (mom and dad) and in each pronuclei there is a chromosome. Goes through synthesis and 2 sister chromatids are produced = 2N,4C
Final product of the DNA synthesis?
2N, 2C
Where does fertilization take place? and how many days does it take for the first cleavage event?
In the fallopian tube and take 2 days after fertilization to go from a 1 cell to a 2 cell
What is formed first when the cell continues to divide?
Morula
What is different about a blastula and a morula?
The blastula contains a fluid filled cavity called a blastocel
What makes up the blastocyst?
Outer cells: Trophoblast
Inner cell: blastocoele and embryoblast (inner cell mass)
What structure implants into the uterus and how many days?
The blastocyst implants into the uterus and it take 6-10 days.
What happens after the blastocyst is implanted into the uterus?
The placenta begins to grow and secretes B-hCG (Used to detect pregnancy) That why you have to wait 6-10 to find out if you are pregnant.
What happens in Gastrulation?
The blastula become a 3 layered structure called gastrula
Layers of the gastrula: Ectoderm, Mesoderm, Endoderm
What develops into the embryo?
The epiblast
How do you know that gastrulation has started?
Because of the primitive streak. The cells of the epiblast invaginate.
What is formed from the Endoderm?
Digestive system, Liver, Pancreas, Lungs (inner layers)
What is formed from the Mesoderm?
Circulatory system, Lungs (epithelial cells), Skeletal system, Muscular system
