embryo development

zygote

fertilized egg

cellular, tissue, organ

three levels of development

cleavage and formation of blastula

two stages of cellular development

cleavage

cell division without growth, DNA replication and mitosis occurs and cells get smaller with each division, forms morula

morula

ball of cells formed during cleavage stage

formation of blastula

the morula allows water to enter the ball of cells and space forms inside

two stages of tissue development

early gastrula and late gastrula

early gastrula

blastula folds in on itself forming ectoderm and endoderm

late gastrula

mesoderm forms

mesoderm

third layer of cells formed between endoderm and ectoderm during late gastrula

endoderm, mesoderm, and ectoderm layers together

germ layers

ectoderm

forms nervous system, epidermis, epithelial lining of mouth and rectum

mesoderm

forms dermis, musculoskeletal, cardiovascular, urinary, reproductive, respiratory, and digestive system

endoderm

forms epithelial lining of digestive, urinary and respiratory tract, and glands

organ development

requires cellular differentiation

being totipotent

every cell in the body contains all the genes necessary to develop into an organ

once cells become differentiated

certain genes are “turned on“ to make the cell a heart cell, nervous cell, skin cell, etc.

stem cells

cells that are undifferentiated

growth factors

proteins that promote cell growth, differentiation, and survival

pluripotency

the ability to become any type of cell

embryonic, adult, induced pluripotent

three types of stem cells

embryonic

type of stem cell that is totipotent/pluripotent, replicated indefinitely, get them from human embryo, controversial, used for drug testing, clinical trials, research

adult

type of stem cell that is multipotent, can only reproduce for the life of the organism, can only make more of the same cell type, get them from skin, retina, bone marrow etc.

induced pluripotent

type of stem cell that is pluripotent, created from adult cell that is reprogrammed to turn it back to pluripotent cell from a multipotent one, can reproduce indefinitely, can differentiate into any cell type in the germ player of the cell it came from

totipotent

can develop into any cell type in adult

pluripotent

cell has developed into a germ cell and can develop into any cell within that germ layer

multipotent

cells that make more cells of the same type

differentiation

cell specialization that occurs at the end of the developmental pathway. the cell had committed and cannot become a different type of cell

in vitro fertilization

where embryos in research come from

fetus cells are already differentiated and multipotent

how do we know embryos used in ESC are not obtained from aborted fetuses

you donate cells to yourself

why adult cells have no possibility of rejection

allows for creation of cell lines that are genetically customized to a patient, no immune rejection

advantages of iPS over ESC