Animal Development Flashcards
(13 cards)
In humans, ovulation occurs and the egg is ready to be fertilized around the __________ day of the menstrual cycle.
14th - 15th
What is the function of the fertilization membrane?
What is the function of the fertilization membrane?
Sequence these stages of early embryonic development.
A fertilized egg undergoes _____ producing a 2-cells stage, then 4-cells, then ______ then _____ then 32-cell. This continues until there is a hollow ball of cells, called the _____.
cleavage
8-cells
16-cells
blastula
Next, cells in one portion of the ball push to the interior to form a tube. The process is called gastrulation, and the result is a _______. At that stage, the 3 germ layers have been laid out, and the destiny of the cells is determined.
gastrula
ectoderm
The epidermis and brain will form from the ______. Most organs, bone, blood, and muscles will develop from ___. The digestive tube, and respiratory organs will form the ______.
mesoderm
endoderm
During early development, embryos of various animal species have
similar characteristics.
If cells of a fertilized egg separate at the 2-cell stage, and both develop, _______ result.
identical twins
If 2 different eggs are fertilized by 2 different sperm at about the same time, the result would be _____.
fraternal twins
When does a human embryo develop a heartbeat?
by Day 21
In humans, the fetus begins to breathe (amniotic fluid) during ________.
week 12 of development
Human fetuses are most susceptible to the effects of teratogens when organs are beginning to form. This is during the _____.
1st three months of development.
Streptomycin may cause hearing loss in the embryo, if taken by the mother during ____
months 1 and 2
Recognize and sequence the events of fertilization and development:
Gamete
→ fertilization → fertilized membrane forms
→ cleavage
→ 2, 4, 8, 16, 32-cell stage → blastulation → blastocyst →
gastrulation → gastrula → organogenesis → birth
