Organogenesis - Lecture notes 2 PDF

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Summary

biochem...

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Organogenesis • The formation and development of organs in an animal (or plant) • Organogenesis takes place in the embryo • Completion of organogenesis => fetal stage Embryo development and organogenesis involve a number of processes • Pattern formation • Positional information specification • Induction • Morphogenesis • Cellular differentiation

There Are three Major Classes of Cell-Surface Receptor Proteins -

Ion-channel coupled receptors G-protein- coupled receptors Enzyme-coupled receptors

Activated Receptor Tyrosine Kinases (RTKs) Phosphorylate Themselves

Organogenesis: -

Cell proliferation Cell specialization Cell interaction Cell movement

Morphogens Are Long-Range Inductive Signals That Exert Graded Effects

Lateral Inhibition Can Generate Patterns of Different Cell Types

Asymmetric progression

Repositioning of cells The cells that express Twist move into the interior of the embryo to form mesoderm. Cell Specification The human body comprises approximately 200 distinct cell types with unique molecular and function characteristics . • These are generated during embryogenesis. Process is tightly regulated • Cellular and regional changes in embryonic development following predefined pattern. • Processes manifest as folds, splits condensation • Evolutionary conservation of biological processes • Organ development from endoderm, mesoderm, ectoderm in 3rd to 8th week in utero. • Controlled by intrinsic and extrinsic factors.

Cell specification and determination Two different cell fates: • Determined fate = irreversible. • Committed cells, tendency to developmental path but still able to change fate with sufficient stimulus There are two main types of specification: • Autonomously specified cells develop into a specific fate based upon cytoplasmic determinants with no regard to the cell’s environment (intrinsic). • Conditionally specified cells develop into a specific fate based upon other surrounding cells or morphogen gradients (extrinsic)....