Brain Research Bulletin 66 (2005) 445–448 Pallial expression of Enc1 RNA in postnatal mouse telencephalon Elena Garc´ ıa-Calero * , Luis Puelles Department of Human Anatomy and Psychobiology, Faculty of Medicine, University of Murcia (Campus Espinardo), 30100 Murcia, Spain Available online 2 June 2005 Abstract We analysed the pallial expression pattern of Enc1 (a member of the kelch family of genes) in postnatal mice (P1–P10). At early developmental stages this gene plays a role in the histogenesis of cortical structures [M.C. Hern´ andez, P.J. Andr´ es-Barquin, S. Mart´ ınez, A. Bulfone, J.L.R. Rubenstein, M.A. Israel, Enc1: novel mammalian kelch-related gene specifically expressed in the nervous system encodes an actino-binding protein, J. Neurosci. 17 (1997) 3038–3051]. A restricted expression of Enc1 was found in the mouse pallium, notably within claustroamygdaloid derivatives of the lateral pallium and in some cortical layers in the lateral, dorsal and medial pallium sectors, with distinct regional differences. The strongest cortical expression was found in isocortical layer II and in the piriform cortex, anterior olfactory area and olfactory bulb mitral cells. The lowest signal occurred in the retrosplenial cortex. The subgranular layers V/VI were also positive, particularly layer V, with clearcut areal differences. The hippocampal CA3/CA4 areas and the dentate gyrus were strongly positive. The dorsolateral (core) portion of the claustrum and dorsal endopiriform nucleus were moderately positive, as were the amygdaloid lateral and basolateral nuclei. © 2005 Elsevier Inc. All rights reserved. Keywords: Cerebral cortex; Cortical areas; Lateral pallium; Dorsal pallium; Medial pallium; Claustrum; Amygdala 1. Introduction The major part of the mammalian pallium develops as a layered neuronal structure, the cerebral cortex (subdivided Abbreviations: Acb, accumbens nucleus; Aco, anterior cortical amy- daloid nucleus; AO, anterior olfactory nucleus; BLA, basolateral amygdaloid nucleus, anterior part; Bol, olfactory bulb; BLP, basolateral amygdaloid nucleus, posterior part; BST, bed nucleus of the stria terminalis; CA1–4, fields 1–4 of Ammon’s horn; cc, corpus callosum; Cig, cingulate cortex; Cl, claustrum; CPu, caudate-putamen; DG, dentate gyrus; DP, dorsal peduncular cortex; Ent, entorhinal cortex; EP, endopiriform nucleus; FL, cortical sen- sory representation of the forelimb; Fr, frontal cortex; GP, globus pallidus; HL, cortical sensory representation of the hindlimb; IG, indusium griseum; IL, infralimbic cortex; Ins, insular cortex; La, lateral amygdaloid nucleus; LOT, nucleus of the lateral olfactory tract; LSD, lateral septal nucleus, dor- sal part; LSI, lateral septal nucleus, intermediate part; LSV, lateral septal nucleus, ventral part; Occ, occipital cortex; Par, parietal cortex; Pir, piri- form cortex; Po, posterior thalamic nuclear group; Prh, perirhinal cortex; RSA, retrosplenial agranular cortex; RSG, retrosplenial granular cortex; SI, innominate substance; Su, subiculum; Te, temporal cortex; TT, taenia tecta; Tu, olfactory tubercle; VMH, ventromedial hypothalamic nucleus; VPM, ventral posteromedial thalamic nucleus; ZID, zona incerta, dorsal part * Corresponding author. Tel.: +34 968 363954; fax: +34 968 363955. E-mail address: ecalero@um.es (E. Garc´ ıa-Calero). into differentiated iso- and allocortical sectors [2,10], and these into a number of areas), but the pallium encloses also a number of underlying claustroamygdaloid nuclear deriva- tives [8,3,5] (we leave aside here the tangential migration of subpallial GABAergic neurons into the pallium). Every cortical area and pallial nucleus is characterized by its own cytoarchitecture, connections and function. The development of this complexity is controlled by genetic patterning acting already upon the proliferating pallial progenitors [9,6], and is modulated later in development by added epigenetic effects (i.e., migration of immature neurons into specific layers, development of thalamic or cortical afferent inputs [7,11]). Gene markers that appear restricted to specific areas, lay- ers or nuclei within the pallium are of interest in studies of the patterning mechanisms that lead to pallial differentiation in mammals. Preliminary data indicated a parcellated pallial expression of the gene Enc1 in mouse cerebral cortex, moti- vating us to analyse in detail its expression at postnatal stages. The Enc1 gene (Ectoderm and Neural-Cortex 1) is a mem- ber of the kelch family, and encodes a cytoplasmic protein that interacts with actin [14,4]. This product is present in mouse telencephalon already at early stages of development, where 0361-9230/$ – see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.brainresbull.2005.05.003