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#determination

2 public questions tagged with this topic.

Specification Determination-l

Determination differs from specification because:

Specification and determination both indicate commitment but differ fundamentally in stability and reversibility. Specification is labile; tissue cultured neutrally follows preferred pathway, yet when grafted into foreign embryonic region receiving different BMP, Wnt or FGF signals, it can alter fate to match host. Determination involves molecular lockdown through cis-regulatory modifications, DNA methylation, Polycomb repression of alternative programs and autoregulatory transcription factor circuits exemplified by MyoD autoactivation in muscle. Determined cells maintain donor identity after transplantation into confrontational environments, resisting reprogramming and demonstrating self-sustaining fate maintenance without ongoing external instruction.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 5: Determination as Irreversible Commitment.

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Specification Determination-ll

Which of the following statements best defines determination?

Determination is conceptualized as the stable, essentially irreversible commitment of a cell to a particular differentiation pathway, following an earlier labile specification phase. During specification, fate preference is established but can still be redirected by changing embryonic environment or transplantation. Determination involves profound molecular stabilization including positive feedback loops among selector genes like MyoD in myoblasts, extensive chromatin remodeling, DNA methylation and Polycomb-mediated repression of alternative programs. Once determined, cells execute differentiation autonomously even when grafted into foreign regions that would normally induce different fates, maintaining original identity despite contradictory signals.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 5: Determination and Specification Concepts.

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