Normally unused positional cues guide ectopic afferents in the leech CNS

Area of Science:

• Neuroscience
• Developmental Biology
• Animal Behavior

Background:

• Peripheral sensory neurons in the leech Hirudo medicinalis form distinct ventral longitudinal tracts.
• A unique lateral tract, the
• Purpose_of_the_Study

Purpose of the Study:

• Investigate segmental differences in pathway cue distribution for sex afferents.
• Determine the specificity of central pathway selection by these axons.

Main Methods:

• Transplantation of male genitalia primordia to ectopic positions.
• Labeling of ectopic sex afferents to trace their paths within the central nervous system (CNS).
• Ablation of genitalia to observe the absence of the lateral tract.

Main Results:

• In approximately 50% of experimental leeches, afferent axons from transplanted genitalia formed a distinct lateral fiber bundle in nearby ganglia.
• This ectopic tract occupied a position analogous to the normal lateral tract in the sex ganglia.
• The sex afferents successfully navigated to their normal pathways in inappropriate segmental ganglia.

Conclusions:

• Positional cues for afferent axon pathway selection are present in all segments of the leech CNS.
• These cues are accessible to afferent axons regardless of segment-specific usage.
• Pathway selection by sex afferents is specific and not limited to their native segmental ganglia.