Ultrastructure of the dorsal cortex of the lizard Psammodromus algirus.

The dorsal cortex of Psammodromus algirus shows three layers, superficial plexiform layer (SPL), cellular layer (CL), and deep plexiform layer (DPL), from the pia mater to the ependyma. The marginal glial sheet constitutes the outer limit of the SPL. This glial sheet consists of flattened tanycytic processes running parallel to the cortical surface. A few globous neurons are scattered within the neuropil of the SPL which is formed by axons, axon terminals, dendrites and dendritic spines. Three types of axon terminals, type S, type F, and axon terminals with large dense core vesicles, can be observed in the SPL. The CL presents numerous neuronal somata tightly packed. Large neurons with spherical to oval nucleus and dispersed chromatin, and smaller neurons with chromatin clumps are found in this layer. The DPL consists of neuropil with many solitary or clustered neurons. Three neuronal types are found: neurons with indented nucleus, small neurons with spherical nucleus and large juxtaependymal neurons. Glial cells are present throughout the dorsal cortex. Astrocytes are most abundant and do not show a defined pattern of distribution. Oligodendrocytes are frequently related to the alveus fibers. The ependyma forms the ventral limit of the dorsal cortex. It is formed by clear and electron-dense cells.