Submission Date

4-29-2026

Document Type

Paper- Restricted to Campus Access

Department

Neuroscience

Adviser

Ellen Dawley

Committee Member

Karen Clemente

Committee Member

Erica Gorenberg

Department Chair

Carlita Favero

Project Description

Unlike mammalian systems—where neurogenic potential declines sharply after development and injury responses favor glial scarring over neuronal replacement—the axolotl maintains an active ependymal neuroepithelium that generates new neurons throughout adulthood. This study investigates the cellular dynamics that underlie this indeterminate spinal cord growth, focusing on how newborn neurons mature, migrate, and integrate into an expanding neural architecture. Using double immunofluorescence for Doublecortin (DCX) and Neuronal Nuclei (NeuN), I mapped spatial gradients of neuronal development along the proximodistal axis of the growing tail. Distal regions contained dense populations of DCX‑positive immature neurons with diffuse NeuN expression, indicating early post‑mitotic states. Middle regions revealed transitional neurons exhibiting punctate DCX/NeuN co‑labeling at the base of trailing processes, marking a distinct intermediate maturation phase. Proximal regions displayed stratified dorsal layers of NeuN‑positive mature neurons, with persistent DCX‑positive fibers suggesting ongoing tangential migration even in older tissue. Preliminary double labeling with glial fibrillary acidic protein (GFAP) showed no overlap between GFAP‑positive radial glial fibers and DCX‑positive neurons, indicating that axolotl neuroblasts do not use the radial glial scaffold typical of many vertebrate systems. Instead, their morphology and orientation suggest a tangential, axon‑associated mode of migration. Together, these findings reveal a spatially ordered sequence of neuronal maturation and a migratory mechanism that supports continuous spinal cord extension. By establishing a baseline model of normal axolotl neurogenesis, this work provides a foundation for understanding how lifelong growth and regenerative capacity intersect in the vertebrate CNS.

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