Delayed neural crest cell emigration from Sp and Spd mouse neural tube explants

Area of Science:

• Developmental Biology
• Genetics
• Neuroscience

Background:

• Splotch (Sp) and splotch-delayed (Spd) are allelic mouse mutations.
• Homozygous embryos exhibit neural tube defects (NTDs) and neural crest cell (NCC) deficiencies.
• Spd mutants sometimes show NCC derivative issues without NTDs, suggesting a common regulatory event.

Purpose of the Study:

• Investigate the basis of aberrant NCC derivatives in Sp and Spd mutants.
• Examine the potential common regulatory event affecting neurulation and NCC release.
• Determine if defects in NCC release contribute to NTDs.

Main Methods:

• Caudal neural tubes from day 9 Sp and Spd embryos were cultured for 72 hours.
• Cultures were performed on gelatin-coated dishes (planar) and 3D basement membrane matrigel.
• Cytogenetic markers were used for embryo genotyping.

Main Results:

• A delay in NCC release from the neural tube was observed in both Sp and Spd mutants, particularly Sp.
• NCC outgrowth and emigration were significantly reduced in mutant cultures after 24 hours compared to controls.
• No differences in mitotic indices were found among emigrated NCCs.
• After 72 hours, mutant and control cultures showed similar outgrowth, cell number, and migration.
• A 24-hour delay in NCC outgrowth was consistent across both culture conditions.

Conclusions:

• The primary defect in Sp and Spd mutants is a delay in the release of NCCs from the neural tube.
• This delay suggests the defect resides within the neuroepithelium.
• Understanding NCC release mechanisms is crucial for addressing NTDs in these mutants.