Cholecystokinin Innervation of the Cerebral Cortex in a Reptile, the Lizard <i>Psammodromus algirus</i>

Abstract

We used light and electron microscopic and immunohistochemical methods to map the distribution of cholecystokinin (CCK) in the cerebral cortex of a lizard, Psammodromus algirus. At light microscopy, the CCK immunoreactivity was limited to fibers and terminals densely innervating all cortical regions except for the lateral (pyriform) cortex which was very slightly immunostained. The CCK-positive terminals were almost restricted to the cell layers in every cortical region where they surrounded immunonegative cell bodies and proximal dendrites of neurons within the layer. No CCK-containing neurons were observed within the cerebral cortex. At the electron microscopic level, most positive structures were presynaptic boutons contacting cell bodies and proximal dendrites. All contacts appeared to form symmetric junctions. both the distribution and type of synaptic contacts of CCK fibers in the cerebral cortex of Psammodromus are very similar to the corresponding features in the hippocampus of mammals, although in this lizard the CCK cortical innervation, unlike that in mammals, is probably of extrinsic origin. Double HRP-retrograde labeling and CCK immunohistochemistry show that part of the CCK in the cerebral cortex of Psammodromus arises from the hypothalamic supramammillary nuclei.

Comments on the Updated Tetrapartite Pallium Model in the Mouse and Chick, Featuring a Homologous Claustro-Insular Complex

“…These cases show retrograde labeling of cells in the dorsal cortex. Guirado et al [1998] also showed one experiment in a lizard, in which HRP was injected precisely within the area now deduced to be the reptilian LPall [Puelles et al, 2016a. Retrogradely labeled cells appeared distinctly within the whole dorsal cortex (their Fig.…”

Selective early expression of the orphan nuclear receptor Nr4a2 identifies the claustrum homolog in the avian mesopallium: Impact on sauropsidian/mammalian pallium comparisons

“…5,11). In contrast, the DVR of reptiles seems to present mainly a VPall bulge, or separately bulging VPall and LPall sectors, and the LPall may bulge only transiently (Kuhlenbeck, 1927(Kuhlenbeck, , 1973(Kuhlenbeck, , 1977Schepers, 1948;Striedter, 1997;Guirado et al, 1998;Bruce, 2007;Suzuki and Hirata, 2014;Fig. 11).…”

Nature at Work: Ongoing Saga of Evolution

“…118 In these plants foraging by insects facilitates dispersal of pollen grains in the air but the may not actually pollinate the flowers. 120 In closed tropical conditions wind pollination may not always correlate completely with anemophilous syndrome. 120 In closed tropical conditions wind pollination may not always correlate completely with anemophilous syndrome.…”

“…27,11 8 Anatomically, reptilian dorsal cortex resembles with the isocortex of mammals in many respect. The three neurons of reptilian dorsal cortex namely bitufted neurons, multipolar neurons and pyramidal neurons have formed the basis for comparing the medial aspect of dorsal cortex being homologous to the mammalian hippocampal formation, [119][120] whereas the lateral aspect of the dorsal cortex has been compared to the mammalian isocortex, or at least to part of it. 107,121 Anatomically the dorsal cortex of reptiles differ from the isocortex in being three layered instead of six layered and in lacking columnar organization.…”