Developmental Biology Expert

---
name: developmental-biology-expert
version: 1.0.0
description: Expert-level developmental biology covering embryogenesis, cell fate determination, morphogen gradients, organogenesis, stem cells, and regenerative medicine.
author: luo-kai
tags: [developmental biology, embryogenesis, stem cells, morphogens, organogenesis]
---

# Developmental Biology Expert

## Before Starting
1. Which model organism? (Drosophila, C. elegans, zebrafish, mouse, Xenopus)
2. Which developmental process?
3. Basic development or regenerative medicine focus?

## Core Expertise Areas

### Early Embryogenesis
Fertilization: acrosome reaction, cortical reaction, zygote formation.
Cleavage: rapid cell division without growth, blastomere formation.
Blastulation: blastocyst (mammals) or blastula (non-mammals), inner cell mass.
Gastrulation: three germ layers — ectoderm, mesoderm, endoderm.
Neurulation: neural plate, neural tube formation, neural crest migration.

### Cell Fate and Patterning
Induction: one tissue instructing adjacent tissue to change fate.
Morphogen gradients: Bicoid, Sonic Hedgehog, BMP, Wnt — concentration encodes position.
French flag model: threshold concentrations specify different cell fates.
Positional information: cells read their position and differentiate accordingly.
Hox genes: homeotic genes specifying anterior-posterior body axis identity.

### Signaling Pathways in Development
Wnt: anterior-posterior patterning, cell proliferation, stem cell maintenance.
Notch: lateral inhibition, boundary formation, binary cell fate decisions.
Hedgehog: limb development, left-right asymmetry, neural tube patterning.
FGF: mesoderm induction, limb outgrowth, tissue maintenance.
BMP: dorsal-ventral patterning, bone formation, apoptosis.

### Stem Cells
Totipotent: can form entire organism including extraembryonic tissues.
Pluripotent: can form all three germ layers (ESCs, iPSCs).
Multipotent: restricted to specific lineages (HSCs, NSCs).
iPSC reprogramming: Yamanaka factors (Oct4, Sox2, Klf4, c-Myc).
Niche: microenvironment maintaining stem cell self-renewal.

## Key Patterns



## Best Practices
- Consider both cell-autonomous and non-autonomous mechanisms
- Use multiple model organisms to distinguish conserved from species-specific mechanisms
- Distinguish instructive from permissive inductions
- Validate morpholino knockdowns with rescue experiments or CRISPR
- Consider timing — same signal can have different effects at different stages

## Common Pitfalls
| Pitfall | Fix |
|---|---|
| Confusing induction and competence | Both signal and receptive tissue required |
| Morpholino off-target effects | Always include p53 morpholino control |
| Oversimplifying stem cell potency | Potency is context and assay dependent |
| Ignoring extraembryonic tissues | Placenta and yolk sac profoundly influence embryo |

## Related Skills
- cell-biology-expert
- molecular-biology-expert
- genetics-expert
- physiology-expert