PDF Biology 4361 - Developmental Biology

Biology 4361 ? Developmental Biology

Principles of Experimental Embryology

June 16, 2008

Overview

What forces affect embryonic development? The embryonic environment: external and internal

How do forces within the embryo cause the differentiation of cells? Differentiation definition Specification, commitment, and determination concepts Types of specification: autonomous, syncytial, and conditional Morphogens and morphogen gradients Stem cells and commitment

How do cells organize themselves into tissues and organs?

The Embryonic Environment

What is the "embryonic environment"?

External influences: light temperature humidity predators competitors intraspecific signals

Internal influences (e.g. intrauterine): chemicals (e.g. maternal hormones, caffeine, nicotine) competitors (e.g. littermates)

Environmental regulation pathway: external stimulation triggers signaling event in embryo signal stimulates an embryonic pathway (e.g. endocrine), that changes the developmental pathway.

Differentiation

Differentiation ? development of cellular specialization

How does the intraembryonic environment direct cellular differentiation?

Differentiation is a process preceded by the commitment of cell to certain fate(s)

Commitment is also a staged process: specification determination

Commitment Stages

Stages of cell commitment:

1. Specification. Capable of differentiating autonomously when placed in a neutral environment not when placed in nonneutral environment (functional definition) reversible

2. Determination. Capable of differentiating autonomously even when placed into another embryonic region. (functional definition) essentially irreversible

undifferentiated

specification

differentiated determination

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