Unlike mammals, species such as fish and amphibians can regenerate damaged spinal
cords, offering insights into potential therapeutic targets. This study investigates the
structural features of the molly fish spinal cord through light and electron microscopy.
The most notable characteristic was the presence of Mauthner cells (M-cells), which
exhibited large cell bodies and processes, as well as synaptic connections with astrocytes. These astrocytic connections contained synaptic vesicles, suggesting electrical
transmission at the M-cell endings. Astrocytes, which were labeled with glial fibrillary
acidic protein (GFAP), contained cytoplasmic glycogen granules, potentially serving as
an emergency fuel source. Two types of oligodendrocytes were identified: a small,
dark cell and a larger, lighter cell, both of which reacted strongly with oligodendrocyte
transcription factor 2 (Olig2). The dark oligodendrocyte resembled human oligodendrocyte precursors, while the light oligodendrocyte was similar to mature human oligodendrocytes. Additionally, proliferative neurons in the substantia grisea centralis
expressed myostatin, Nrf2, and Sox9. Collectively, these findings suggest that the
molly fish spinal cord has advanced structural features conducive to spinal cord
regeneration and could serve as an excellent model for studying central nervous system regeneration. Further studies on the functional aspects of the molly fish spinal
cord are recommended.