Evidence for neurogenesis in the medial cortex of the leopard gecko, Eublepharis macularius

Abstract

Although lizards are often described as having robust neurogenic abilities, only a handful of the more than 6300 species have been explored. Here, we provide the first evidence of homeostatic neurogenesis in the leopard gecko (Eublepharis macularius). We focused our study on the medial cortex, homologue of the mammalian hippocampal formation. Using immunostaining, we identified proliferating pools of neural stem/progenitor cells within the sulcus septomedialis, the pseudostratified ventricular zone adjacent to the medial cortex. Consistent with their identification as radial glia, these cells expressed SOX2, glial fibrillary acidic protein, and Vimentin, and demonstrated a radial morphology. Using a 5-bromo-2′-deoxyuridine cell tracking strategy, we determined that neuroblast migration from the ventricular zone to the medial cortex takes ~30-days, and that newly generated neuronal cells survived for at least 140-days. We also found that cell proliferation within the medial cortex was not significantly altered following rupture of the tail spinal cord (as a result of the naturally evolved process of caudal autotomy). We conclude that the sulcus septomedialis of the leopard gecko demonstrates all the hallmarks of a neurogenic niche.

Spontaneous neuronal regeneration in the forebrain of the leopard gecko (Eublepharis macularius) following neurochemical lesioning

“…Characteristically, these Iba-1+ cells were small-bodied with one or more branching radial processes, consistent with their identification as ramified (or resting) microglia. As has been previously reported, 21 prior to lesioning tomato lectin immunostaining was restricted to endothelial cells of blood vessels (Figure 5F). By 4 dpi, numerous condensed, hyperchromatic pyknotic nuclei and large vacuoles were observed bilaterally within the cellular layer of both the left and right medial cortices, as well as throughout the inner and outer plexiform layers (Figure 5G).…”

Mechanical Brain Injury Increases Cells’ Production of Cystathionine β-Synthase and Glutamine Synthetase, but Reduces Pax2 Expression in the Telencephalon of Juvenile Chum Salmon, Oncorhynchus keta

“…However, the results of studies on the medial cortex in the leopard gecko Eublepharis macularius show the presence of proliferating pools of neural stem/progenitor cells in the septomedialis sulcus , a ventricular zone adjacent to the medial cortex. These cells express sex determining region Y-box 2 (SOX2), glial fibrillar acidic protein (GFAP), and vimentin, and have a radial glial morphology [ 9 ]. Nerve tissue can be partially or completely regenerated in certain areas of the brain in cartilaginous fish.…”

Individual and age-related variation of cellular brain composition in a squamate reptile

“…However, the existence of substantial neurogenesis throughout life [10–14] (reviewed in [15]) might potentially result in a higher variation in neuronal numbers in adult animals, complicating quantitative comparative studies. To assess this, we tested individual variation in the brain (divided into cerebral hemispheres and rest of the brain) mass and number of neurons and non-neuronal cells in a model reptile.…”