Towards A Structural Characterization of The Leopard Gecko Cerebellum: Purkinje Cells And Cells of The External Granular Layer

Abstract

The cerebellum is a major component of the hindbrain, and plays important roles in motor coordination, posture, and cognitive functions. Although the gross anatomy and histological organization of the cerebellum has been documented across many species, less is known about the contributing cell types, especially among non‐mammals. Here we focus on Purkinje cells (PC) and cells of the External Granular Layer (EGL) in a representative lizard, the leopard gecko (Eublepharis macularius). PC serve as the major motor output of the cerebellum. Similar to other vertebrates, gecko PC are large, calbindin‐immunopositive neurons located at the junction between the molecular layer and the granular layer. Golgi‐cox impregnation reveals a dendritic arborization broadly comparable with that of alligators (and distinct from that of mammals). There is typically a single, lengthy primary dendrite that passes towards the molecular layer. This primary dendrite divides into multiple short dendritic branches that conclude in thin spiny branchlets with abundant, closely packed spines. Adult geckos also retain an EGL, a progenitor cell population that characteristically disappears prior to adulthood in mammals. Cells of the gecko EGL are immunopositive for the transcription factor SOX2, a hallmark protein of neural stem/progenitor cells, and the intermediate filament (and radial glia marker) glial fibrillary acid protein, but are immunonegative for NeuN, a marker of mature neurons. Using a bromodeoxyuridine pulse‐chase strategy, we determined that a subset of gecko EGL cells were label retaining after a 140 day chase period. Combined, these data provide important new information about the evolutionary variability of the cerebellum, with implications for functional adaptations in a species capable of tail loss.Support or Funding InformationNatural Sciences and Engineering Research Council Discovery Grant #400358 (MKV), #436190 (CDCB) and The Canada Foundation for Innovation #25371 (MKV) and #30381 (CDCB)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.