An ultrastructural analysis of abnormal otic development in exencephalic mutant mice

Area of Science:

• Developmental biology
• Genetics
• Cell biology

Background:

• Homozygous loop-tail (Lp/Lp) mice present with neural dysraphism.
• Otic pit development is crucial for inner ear formation.

Purpose of the Study:

• To investigate the otocyst defects in Lp/Lp mice.
• To characterize cellular and extracellular matrix abnormalities in the developing otic pit.

Main Methods:

• Morphological analysis of otic pit development in embryonic day 19 Lp/Lp mice.
• Transmission electron microscopy with glutaraldehyde-tannic acid fixation.

Main Results:

• Otic pit cells in Lp/Lp embryos are flattened with abnormal luminal contours.
• Reduced apical filaments and increased globular material observed in ventral otic pit cells.
• Basal lamina shows irregular, clumped lamina densa and disorganized fibrils.

Conclusions:

• Lp/Lp mice exhibit significant otocyst malformations.
• Abnormalities in otic pit cell morphology and basal lamina structure are present.
• These defects likely result from disrupted developmental interactions involving the neural tube and surrounding mesenchyme.