Analysis of neurulation in a mouse model for neural dysraphism

Area of Science:

• Developmental Biology
• Genetics
• Morphogenesis

Background:

• The loop-tail (Lp) mouse mutant exhibits neural tube defects, including failure of neural fold fusion and neuraxis shortening.
• Understanding the cellular mechanisms underlying these developmental abnormalities is crucial for identifying causes of congenital birth defects.

Purpose of the Study:

• To quantitatively analyze the orientation of mitotic spindles in the neuroepithelium of Lp/Lp mutant mouse embryos.
• To correlate neuroepithelial mitotic orientation with neuraxial elongation and neural fold fusion defects.
• To investigate the role of mitotic cell orientation in the underlying gut and notochord in Lp mutant embryos.

Main Methods:

• Quantitative analysis of longitudinally oriented mitoses in the neuroepithelium of homozygous loop-tail (Lp) mutant mouse embryos.
• Comparison of mitotic cell orientation in the neuroepithelium, gut, and notochord between Lp/Lp and normal embryos at specific developmental stages (7-11 and 15-20 somites).

Main Results:

• A significantly lower percentage of longitudinally oriented mitotic spindles was observed in the neuroepithelium of Lp/Lp embryos at the 7- to 11-somite stage compared to normal embryos.
• No significant differences in mitotic spindle orientation were found in the gut or notochord between Lp/Lp and normal embryos at the 7- to 11-somite stage.
• By the 15- to 20-somite stage, significant differences in mitotic spindle orientation were absent in the neuroepithelium, gut, or notochord between mutant and normal embryos.

Conclusions:

• A reduced proportion of longitudinally oriented neuroepithelial spindles during neural fold elevation and fusion may contribute to the neuraxial elongation and closure defects observed in Lp/Lp embryos.
• The shortened gut and notochord in Lp/Lp mutants may not be a direct consequence of defective mitotic spindle orientation in these tissues.