Early Human development Flashcards
Ectodermal germ layer
Outside, nervous and skin tissue
Mesodermal germ layer
In between tissues, muscular and skeletal system
Endodermal germ layer
Inside tissues and gut system
Fertilisation process
Occurs in fallopian tube - Sperm travels through corona radiata -> zona pellicuda
-> Sperm fuses with oocyte
Zygote cleavage
Day 1. Two cell stage
Day 2. Cleavage of zygote results in four cells
Day 4. Loosley packed cells - Morula formed
Day 5. Cells tightly packed - Blastocyst
Blastocyst
Hollow ball of epithelial cells
Implantation
Blastocyst embedded into uterine wall stimulates placenta production
Trophoblast
Give rise to embryonic tissue
Syncytiotrophoblast & Cytotrophoblast
Produce ectodermal tissue, Placenta
Secrete enzymes for blastocyst embedment and hormones for uterus intactment
Hypoblast
Give rise to endodermal tissue - Gut
Epiblast
Give rise to ectodermal tissue
Inner mass cell purpose
Divide and rearrange to form embronic disc and three germ layers
Gastrulation
Formation of three germ layers
Primitave streak
Formation of this streak on back of embryo initiates gastrulation
NOTO cord
Mesoderm that defines where the back bone will be
Embryonic folding
Embryonic disc folds inward to form gut - Ectodermal layer folds inward of mesoderm pinching of yolk to form the gut where endoderm is the hollow tube of the gut
Stem Cells
Replace, regenerate daughter cells for growth, renewal and repair
Totipotent stem cell
Give rise to embryonic tissues and body cells
Pluripotent stem cell
Give rise to all body cells that become committed to pathways
Multipotent stem cell
Give rise to all cells within particular organ
Nullipotent stem cell
Give rise to only once cell type
Unipotent
Renew skin cells
Decreasing development potential
Cells become fixed on a pathway and fixed/limited to a certain fate
