T6: Nervous System

potency specifies the potential to differentiate into different cell types

Zygote (1 day old), morula (3 days old): cells can differentiate and produce all the cells in an organism, including extraembryonic tissues

Inner cell mass of blastocysts (5-7 days old): cells can differentiate into any of three cell masses (endoderm, mesoderm, or ectoderm); originate as inner mass cells within the blastocyst and go on to develop the spectrum of body cells and tissues

Cells from a single germ layer (ex: mesoderm) in 3 week old embryo; cells whcih can differentiate into 2 or more cell types

Terminally differentiated to form only on cell type (ex: neuron)

Many tissues in both children and adults contain populations of stem cells that renew themselves continually and divide to produce new tissue cells as needed

Study of origin and devleopment of a single individual

Prenatal period
-embryonic period: first 8 weeks
-fetal period: 9 weeks

Fertilization ->1 week conceptus-> 3 week embryo (3mm) -> 5 week embryo(10mm)->8week embryo (22mm)

duration: 1st 8 weeks postfertilization
major events: organs form from 3 primary germ layers; basic body plan emerges

Ectoderm, nervous tissue

mesoderm, muscle and connective tissue

endoderm

Brain, spinal cord, skin epidermis

Bones, muscle, connective tissue including dermis, epithelium inside blood vessels (endothelium), epithelium linging ventral body cavities (mesothelium)

Forms inner epithelial lining of the gut tube and its derivative respiratory tubes, digestive organs, and urinary bladder) nd secretory cells of some glands

-Epithelial tissue: covering
-Connective tissue: support
-Mucle tissue: movement
-Nervous tissue: control