Lab2 Embryonic Development Flashcards
Embryology involves:
1- growth in cell number (thru mitosis)
2- differentiation of cellular specializations
3- morphogenesis to form functioning organ systems
Embryology
Study of development of new individual
Fertilization
Sperm+ egg= zygote
Cleavage stages
Division of zygote into smaller and smaller cells form….
Blastomeres
Identical cells
Morula
- “mulberry”
- solid ball of cells (~32 cells)
Blastula
- AKA blastocyte
- hollow ball of cells
Trophoblast
Becomes chorion which will form fetal side of placenta
Intercell mass(ICM)
will form embryo
7 days old
Implantation of blastocyte with ICM next to uterine wall
Thru day 14
Trophoblast secretes enzymes to allow burrowing into uterine blood supply
Last cleavage stage
Uterine mucosa grows over implanted blastocyte
- uterine portions will form placenta
Gastrulation
Invagination or enrolling if cells to form 3 germ layers :
1. Endoderm
2. Mesoderm
3. Ectoderm
Basic body plan of organism is now established
Fetus
9th week of development thru birth
Growth
Increase in size by cell division AKA mitosis and enlargement of individual cells.
Ectoderm
Epidermis, nervous system, hair , nails
Mesoderm
Skeleton, muscle , connective tissue , blood vessels , dermis of the skin , walls of digestive organs , urinary system
Endoderm
Lining of digestive and respiratory tracts
Placenta
Forms from uterine tissue and chorion( differentiated from trophoblast) with its chorionic villi
Amnion
Forms from ICM to form a fluid- filled chamber around the embryo for protection
Umbilical chord
Body stalk that connects embryo to placenta
