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Updated: Aug 12, 2026
Whole-mount Imaging of Mouse Embryo Sensory Axon Projections
Published on: December 9, 2014
The development and pathogenesis of the sensory neuropathy in the mutant rat mf
Abstract:
A study was made of the development of sensory pathways in the mutant rat mutilated foot (mf) which is affected by a sensory neuropathy with autosomal recessive inheritance. Microscopic abnormalities are well recognizable at the fifteenth embryonic day. By day 16, dorsal root ganglia are smaller than normal and show more numerous foci of cell necrosis which continue throughout the remainder of gestation and during the first and second postnatal days. During this period the number of ganglion cells decreases sharply. Reconstruction of cell volumes shows that the larger cells are more severely affected. The secondary sensory nuclei (gracile nuclei) are normal at birth but during the first two postnatal weeks become progressively smaller than in normal rats. The results suggest that the mutant gene acts primarily on the dorsal root ganglia causing excessive neuronal cell death. Qualitatively, the events in this mutant are closely similar to 'programmed cell death' in the normal. It is likely that neurons of second order nuclei, which are not contacted by afferent fibres, undergo a process of transneuronal degeneration as a secondary effect of excessive ganglion cell loss.
Insights
This study reveals that the mutilated foot (mf) rat mutation causes excessive neuronal cell death in dorsal root ganglia, impacting sensory pathway development. These findings shed light on genetic factors influencing neurodegeneration.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Sensory neuropathies can arise from genetic mutations affecting neuronal development.
- Understanding the mechanisms of neuronal cell death is crucial for neurodegenerative disease research.
Purpose of the Study:
- To investigate the developmental effects of the mutilated foot (mf) mutation on sensory pathways in rats.
- To characterize the cellular and anatomical changes associated with this autosomal recessive sensory neuropathy.
Main Methods:
- Microscopic examination of dorsal root ganglia and secondary sensory nuclei in mf mutant rats during embryonic and postnatal development.
- Cell volume reconstruction to assess the impact on different neuronal populations.
- Comparison of mutant rats with normal littermates.
Main Results:
- Abnormalities in sensory pathways were evident from the fifteenth embryonic day in mf mutant rats.
- Dorsal root ganglia were smaller, with increased neuronal necrosis, particularly affecting larger cells.
- Secondary sensory nuclei (gracile nuclei) showed progressive shrinkage postnatally.
- The mutant gene appears to primarily induce excessive neuronal cell death in dorsal root ganglia.
Conclusions:
- The mutilated foot (mf) mutation leads to significant neuronal loss in dorsal root ganglia, disrupting sensory pathway development.
- The observed neurodegenerative process resembles programmed cell death but is pathologically excessive.
- Secondary degeneration in gracile nuclei is likely a consequence of reduced afferent input from dying sensory neurons.
