PubMed Health⌕ Search

Biomedical subjects

Luis Puelles

Publications and source records attributed to Luis Puelles.

At least 19 recordsLinked to original sources
PubMed2005

Verapamil prevents, in a dose-dependent way, the loss of ChAT-immunoreactive neurons in the cerebral cortex following lesions of the rat nucleus basalis magnocellularis.

In the present study we analysed the neuroprotective effect of the L-type voltage-dependent calcium channel antagonist verapamil on cholineacetyltransferase (ChAT)-immunoreactive neurons in the cerebral cortex of rats with bilateral electrolytic lesions of the nucleus basalis magnocellularis (NBM). Treatment with verapamil (1.0, 2.5, 5.0 and 10.0 mg/kg/12 h i.p.) started 24 h after NBM lesions and lasted 8 days. Animals were sacrificed on day 21 after NBM-lesions. The bilateral NBM-lesions produced significant loss of ChAT-immunoreactive neurons in frontal, parietal and temporal cortex. Although the number of ChAT-positive neurons was significantly higher in NBM-lesioned animals treated with verapamil at a dose of 2.5, 5.0 and 10.0 mg/kg than in saline treated ones, the most significant effect was obtained at a dose of 5 mg/kg. This is, to our knowledge, the first report showing an inverted U-shape mode of neuroprotective action of the calcium antagonist verapamil, at morphological level in this particular model of brain damage. The demonstrated beneficial effect of verapamil treatment suggests that the regulation of calcium homeostasis during the early period after NBM lesions might be a possible treatment to prevent neurodegenerative processes in the rat cerebral cortex.

Analysis of Variance↗
PubMed2005

Pallial expression of Enc1 RNA in postnatal mouse telencephalon.

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. Hernández, P.J. Andrés-Barquin, S. Martínez, 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.

Age Factors↗
PubMed2005

3D modelling, gene expression mapping and post-mapping image analysis in the developing human brain.

As human brain development proceeds, there are complex changes in size and shape, most notably in the developing forebrain. Molecular technologies enable us to characterise the gene expression patterns that underlie these changes. To interpret these patterns the location of expression must be identified and, often, gene expression patterns compared for several genes or across several developmental stages. To facilitate interpretation we have generated a set of three-dimensional models using a recently developed technique, optical projection tomography. The models act as a framework onto which gene expression patterns are mapped and anatomical domains identified using custom-designed software, MAPaint. Here, we demonstrate their use to compare forebrain development at two embryonic stages (Carnegie stages 18 and 21; 44 and 52 days post conception, respectively) and as a means of recording, storing and visualising gene expression data for three example genes EMX1, EMX2 and OTX2. Anatomical domains were also mapped to the models and the comparison of gene expression and anatomical data is demonstrated at Carnegie stage 21. The three-dimensional models and sophisticated software facilitate the analysis and visualisation of morphological changes and gene expression patterns during early brain development and can be applied to the development of other complex structures.

Brain↗
PubMed2005

A distinct preisthmic histogenetic domain is defined by overlap of Otx2 and Pax2 gene expression in the avian caudal midbrain.

Correlative in situ hybridization of Otx2, Pax2, Gbx2, and Fgf8 mRNA probes in adjacent serial sections through the chicken midbrain and isthmus at early to intermediate stages of development served to map in detail the area of overlap of Otx2 and Pax2 transcripts in the caudal midbrain. The neuronal populations developing within this preisthmic domain made up a caudal part of the midbrain reticular formation, the interfascicular nucleus, and the magnocellular (pre)isthmic nucleus, plus the corresponding part of the periaqueductal gray. The torus semicircularis-the inferior colliculus homolog-expressed Otx2 in its ventricular lining exclusively, but it never expressed Pax2. The parvicellular isthmic nucleus, although placed inside the midbrain lobe, never expressed Otx2, and its cells rapidly down-regulated an early transient Pax2 signal; this pattern is consistent with its reported isthmic origin and forward tangential translocation. This analysis reveals the existence of four distinct midbrain histogenetic domains along the longitudinal axis, at least for the alar plate. These presumably result from step-like isthmic organizer effects on Otx2-expressing midbrain neuroepithelium at different distances from a caudal FGF8 morphogen source (isthmic Fgf8-positive domain). The final phenotypes of these domains are histologically diverse and make up the griseum tectale (rostrally), the optic tectum, the torus semicircularis, and the presently characterized preisthmic domain (lying closest to the isthmic organizer). Available comparative data for reptiles and mammals suggest the general validity of this scheme.

Animals↗
PubMed2005

Expression patterns of developmental regulatory genes show comparable divisions in the telencephalon of Xenopus and mouse: insights into the evolution of the forebrain.

In this study, we review data on the existence of comparable divisions and subdivisions in the telencephalon of different groups of tetrapods based on expression of some developmental regulatory genes, having a particular focus in the comparison of the anuran amphibian Xenopus and the mouse. The available data on Xenopus, mouse, chick and turtle indicate that apparently all tetrapod groups possess the same molecularly distinct divisions and subdivisions in the telencephalon. This basic organization was likely present in the telencephalon of stem tetrapods. Each division/subdivision is characterized by expression of a unique combination of developmental regulatory genes, and appears to represent a self-regulated and topologically constant histogenetic brain compartment that gives rise to specific groups of cells. This interpretation has an important consequence for searching homologies, since a basic condition for cell groups in different vertebrates to be considered homologous is that they originate in the same compartment. However, evolution may allow individual cell groups derived from comparable (field homologous) subdivisions to be either similar or dissimilar across the vertebrate groups, giving rise to several possible scenarios of evolution, which include both the evolutionary conservation of similar (homologous) cells or the production of novel cell groups. Finally, available data in the lamprey, a jawless fish, suggest that not all telencephalic subdivisions were present at the origin of vertebrates, raising important questions about their evolution.

Animals↗
PubMed2005

Ontogeny of tyrosine hydroxylase mRNA expression in mid- and forebrain: neuromeric pattern and novel positive regions.

Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the synthesis of catecholamines and, thus, critical in determining the catecholaminergic phenotype. In this study, we have examined the expression of TH mRNA by in situ hybridization in the embryonic mouse forebrain and midbrain and have mapped its localization according to the neuromeric pattern. We find that early in embryonic development, 10 to 12 days post coitum (dpc), TH mRNA is expressed in ample continuous regions of the neuroepithelium, extending across several neuromeres. However, from 12.5 dpc onward, the expression becomes restricted to discrete regions, which correspond to the dopaminergic nuclei (A8 to A15). In addition to these nuclei previously described, TH mRNA is also observed in regions that do not express this enzyme according to immunohistochemical studies. This difference in relation to protein expression pattern is consequent with the known posttranscriptional regulation of TH expression. The most representative example of a novel positive region is the conspicuous mRNA expression in both medial and lateral ganglionic eminences. This result agrees with reports describing the capacity of striatal stem cells (that is, located at the lateral ganglionic eminence) to become dopaminergic in vitro. Other regions include the isthmic mantle layer and the early floor plate of the midbrain-caudal forebrain. On the whole, the expression map we have obtained opens new perspectives for evolutionary/comparative studies, as well as for therapeutic approaches looking for potentially dopaminergic cells. Developmental Dynamics 234:709-717, 2005. (c) 2005 Wiley-Liss, Inc.

Animals↗
PubMed2005

Morphological and molecular analysis of the early developing chick requires an expanded series of primitive streak stages.

A detailed analysis of the gastrulating chick embryo was performed using three methods : time-lapse videotaping of embryos in culture, histological semithin sections, and in situ hybridization with 10 mRNA signals expressed during gastrulation. The results suggest that the gene expression pattern of Goosecoid, Hex, Crescent, and Bmp7 may be involved in the axial establishment of the temporal and spatial arrangement of cells forming the prechordal plate endoderm, and that Chordin, cNot1, Noggin, and Brachyury are precocious markers of cells coming from Hensen's node, which contribute to the rostralmost tip of the notochord, its arrowhead, the head process, and, later, the elongating notochord. These results explain several earlier descriptions based only on morphological analyses of the axial mesodermal structures characteristic of the gastrulation stages. The data, carefully observed and compared with the whole-mount observation in time-lapse video, show that the changes in cell populations, movements, and cell differentiation occur step-by-step over a precise temporal range, which requires the establishment of a subdivision of the stages usually employed. Knowledge of new aspects of avian gastrulation, including gene expression patterns, immunocytochemical analyses, and the great number of recent experiments based on microinjections or transplants of groups of cells to analyze processes of induction or regulation, need the support of a precisely defined scheme of primitive streak stages (PS-stages), and a correlation of these stages with other approaches to provide a finer resolution of the staging steps, and thus to facilitate a better understanding of the initial gastrulation period.

Animals↗
PubMed2005

Postulated boundaries and differential fate in the developing rostral hindbrain.

The vertebrate brain is progressively regionalized during development in a process whereby a precise spatio-temporal arrangement of gene expression patterns and resulting intercellular and intracellular signals drive patterning, growth, morphogenesis, and final fates, thus producing ordered species-specific differentiation of each territory within a shared morphotype. Before genetic and molecular biology tools started to be used to uncover the underlying mechanisms that control morphogenesis, knowledge on brain development largely depended on descriptive analysis and experimental embryology. The first approach allowed us to know how the brain develops but not why. The second provided insights into inductive and field histogenetic phenomena, requiring causal explanation. In this review, we focused on the regionalization of the rostral hindbrain, defined as isthmus plus rhombomere 1, which is the least understood part of the hindbrain. We addressed what is known about the formation of boundaries in this area and the fate of diverse neuroepithelial portions. We introduced to this end some fate-mapping data recently obtained in our laboratory. Starting from the background of pioneering morphological studies and available fate mapping data, we establish correlation with current knowledge about how morphogens, transcription factors, or other signaling molecules map onto particular territories, from where they may drive morphogenetic interactions that generate final fates step by step.

Animals↗
PubMed2005

Agreement and disagreement among fate maps of the chick neural plate.

Fate maps are essential to understand embryonic development; they provide a background for deducing maps of differential cellular specification in the context of other experimental data and molecular expression patterns. Due to its accessibility, the chick neural plate has been fate-mapped many times, albeit without complete agreement with respect to its shape, extent and fated subdivisions. In this review, we first comment about avian neural plate fate maps reported since the early period of experimental embryology, referring to the different methods followed. We next review a perfected fate-mapping methodology, which recently allowed us rather precise delimitation of the chick neural plate at stages 3d/4. This leads to a general discussion about the apparent border of the neural plate and the prospective main rostrocaudal and longitudinal divisions of the neural tube.

Animals↗
PubMed2005

Correlation of a chicken stage 4 neural plate fate map with early gene expression patterns.

A number of gene markers are currently claimed to allow positive or negative visualization of the early chick neural plate at stages 3d/4, when its fate becomes determined. Some markers labeled by various authors as either "neural" or "non-neural" indeed show ectodermal expression patterns roughly correlative with widespread yet vague ideas on the shape and size of the early neural plate, based on previous fate maps. However, for technical reasons, it is not clear how precisely these expression patterns correlate with any experimentally determined fate boundaries. An eventual mismatch between fate and marker interpretation might bear importantly on ideas about gene functions and causal hypotheses in issues such as the establishment of the neural/non-neural border or the earliest mechanisms of neural regionalization. In this review, we correlated a set of epiblastic and mesendodermal gene expression patterns with the novel neuroectoderm proportions suggested by our recent fate map of the chick neural plate at stages HH 3d/4 [P. Fernández-Garre, L. Rodriguez-Gallardo, V. Gallego-Diaz, I.S. Alvarez, L. Puelles, Fate map of the chicken neural plate at stage 4, Development 129 (2002) 2807-2822.]. This analysis suggests the existence of various nested subregions of the epiblast with boundaries codefined by given sets of gene patterns. No gene expression studied reproduces exactly or even approximately the entire neural plate shape, leading to a combinatorial hypothesis on its specification. This kind of analysis (fate and molecular maps), jointly with competence maps, provides the basis for understanding gene functions and the mechanisms of neural induction, specification and regionalization. Several gene patterns observed are consistent with precocious incipient regionalization of the neural plate along the dorsoventral and anteroposterior axes.

Animals↗
PubMed2004

3 dimensional modelling of early human brain development using optical projection tomography.

BACKGROUND: As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped. RESULTS: Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (approximately 300 microm by approximately 150 microm) to the rootlets of cranial nerve XII (approximately 20 microm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is approximately 30 microm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated. CONCLUSION: In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of approximately 20 microm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development.

Brain↗
PubMed2004

Expression of Dbx1, Neurogenin 2, Semaphorin 5A, Cadherin 8, and Emx1 distinguish ventral and lateral pallial histogenetic divisions in the developing mouse claustroamygdaloid complex.

We studied the lateral and ventral pallial divisions of the claustroamygdaloid complex by means of analysis of expression patterns of the developmental regulatory genes Tbr1, Dbx1, Neurogenin 2, Emx1, Cadherin 8, and Semaphorin 5A in mouse developing telencephalon, from embryonic day 12.5 until birth. Our results indicate that these genes help to distinguish distinct lateral and ventral pallial histogenetic divisions in the embryonic telencephalon. Tbr1 is broadly expressed in both lateral and ventral pallial histogenetic divisions (the lateroventral migratory stream plus the mantle) during early and intermediate embryonic development; its signal becomes weak in parts of the mantle during late embryonic development. Dbx1 is strongly and specifically expressed in progenitor cells (ventricular zone) of the ventral pallium during early embryonic development, but there is no signal of this gene in the rest of the pallium nor the subpallium. Neurogenin 2 and Semaphorin 5A are both expressed in a ventral subdivision of the lateroventral migratory stream (called by us the ventral migratory stream). Further, specific nuclei of the claustral complex and pallial amygdala show strong expression of Neurogenin 2 and/or Semaphorin 5A, including the ventromedial claustrum and endopiriform nuclei, the lateral and basomedial amygdalar nuclei, the anterior and posteromedial cortical amygdalar areas, plus the amygdalo-hippocampal area. We interpret these nuclei or areas of the claustroamygdaloid complex as possible derivatives of the ventral pallium. In contrast, during embryonic development the dorsolateral claustrum, the basolateral amygdalar nucleus, and the posterolateral cortical amygdalar area do not express or show weak expression of Neurogenin 2 or Semaphorin 5A, but express selectively and strongly Cadherin 8 plus Emx1, and may be derivatives of the lateral pallium. The lateral pallial and ventral pallial divisions of the claustroamygdaloid complex appear to have some different sets of connections, although this requires further investigation.

Amygdala↗
PubMed2004

Expression of the genes Emx1, Tbr1, and Eomes (Tbr2) in the telencephalon of Xenopus laevis confirms the existence of a ventral pallial division in all tetrapods.

To investigate the pallial organization and the exact location and extension of the ventral pallium in amphibians, we cloned a fragment of the homeobox XenopusTbr1 (xTbr1) gene and analyzed its expression compared with that of the genes xEomes (Tbr2) and xEmx1 in the telencephalon of the frog Xenopus laevis during embryonic and larval development. The expression of xEmx1 was also analyzed in the adult frog. We compared the expression patterns of these pallial marker genes with that of the subpallial gene xDistal-less-4 (xDll4). Our results indicate that the whole pallium of Xenopus expresses the T-box genes xTbr1 and xEomes (in proliferating cells and/or mantle) during embryonic and larval development, and the expression of these genes is topographically complementary to that of xDll4 in the subpallium. In addition to their massive expression in the pallium, both xTbr1 and xEomes are expressed in a few dispersed cells in the subpallium, which may represent immigrant cells of pallial origin, because these genes are not found in the subpallial proliferating cells. On the other hand, during development xEmx1 is expressed in a large part of the pallium (proliferating and postmitotic cells) except for an area adjacent to the pallio-subpallial boundary, where xEmx1 is observed only in some mantle cells. This pallial area poor in xEmx1 expression and poor in expression of the subpallial gene xDll4, but expressing the pallial marker genes xTbr1 and xEomes, appears to represent the amphibian ventral pallium, comparable to that described in other vertebrates (Puelles et al. [2000] J. Comp. Neurol. 424:409-438). In the adult frog, the ventral pallium appears to include the rostral part of the lateral amygdalar nucleus as well as a large part of the medial amygdalar nucleus (as defined by Marín et al. [1998] J. Comp. Neurol. 392:285-312). In contrast, the caudal part of the previously termed lateral amygdalar nucleus shows strong xEmx1 expression and may be a lateral pallial derivative. The possible homology of these amphibian amygdalar nuclei is discussed. Finally, expression of xTbr1, xEomes, and xEmx1 is observed in the mitral cell layer of the olfactory bulb from early developmental stages, further supporting that this structure is a pallial derivative.

Animals↗
PubMed2004

In vivo characterization of the Nkx2.1 promoter/enhancer elements in transgenic mice.

Nkx2.1 encodes a homeodomain transcription factor whose expression is restricted to the thyroid, lung and specific regions of the forebrain. NKX2.1 plays a key role in the development of the latter organs. In lung epithelial cells, two regions of promoter activity, designated as proximal and distal promoters, map to DNA elements located upstream of exons 1 and 2 (within intron 1). That both promoters are active in vivo has been demonstrated by the presence of multiple Nkx2.1 mRNA species with distinct and appropriate exonic composition. The mechanisms of Nkx2.1 tissue selective gene expression remain entirely unknown. We have examined the potential of three overlapping DNA fragments, representing a total of approximately 4 kb of potential regulatory DNA from the baboon Nkx2.1 5' flanking region to direct expression of LacZ in transgenic mice during embryonic development. The three constructs include sequences in proximal, distal and both promoters separately. All three fragments directed LacZ expression to the brain of transgenic E15 and E18 mouse embryos. In addition to a number of other sites, all three constructs were active in subgroups of cells localized in the hypothalamus, a well-established site of endogenous Nkx2.1 gene expression. Two of the fragments conferred tracheal epithelial-specific LacZ gene expression, but parenchymal lung expression was not observed. None of the three fragments had activity in the thyroid. These data demonstrate the complexity of the Nkx2.1 tissue specific gene regulation and suggest that cis-active elements required for tracheal versus lung morphogenesis may be distinct. The same applies to the brain, which provides the most permissive environment for recognition of Nkx2.1 tissue specific cis-active elements.

Animals↗
PubMed2004

OL-protocadherin expression in the visual system of the chicken embryo.

The expression of OL-protocadherin, a homotypically binding cell adhesion molecule, was mapped in the visual system of the chicken embryo at intermediate to late stages of development (11-19 days of incubation). The expression was compared with that of four classic cadherins, described previously. OL-protocadherin is expressed by the isthmooptic nucleus, its retinopetal projection, and possibly its retinal target neurons, the amacrine cells. Ganglion cells begin to express OL-protocadherin at relatively late stages of development. The layers of the optic tectum, the projection neurons in the stratum griseum centrale, and the tectofugal pathways show differential OL-protocadherin immunoreactivity. Several of the diencephalic target nuclei of the tectothalamic projection, such as the principal pretectal nucleus, subpretectal nucleus, and nucleus rotundus, contain distinct subregions or populations of neurons expressing OL-protocadherin. In these centers, the expression pattern of OL-protocadherin differs from that of the four classic cadherins, though it shows partial overlap with them. Other retinorecipient and/or tectorecipient nuclei (ventral geniculate nucleus, lateral dorsolateral nucleus, superficial synencephalic nucleus, pretectal area, and griseum tectale) also show a differential immunoreactivity for OL-protocadherin and other cadherins. Some of these nuclei and the optic tectum display a similar sequence of cadherin expression from superficial to deep layers, in a pattern that may reflect mutual interconnections. This result indicates a partial conservation of cadherin expression across interconnected embryonic divisions, from the mesencephalon to the ventral thalamus. In conclusion, OL-protocadherin is a marker for specific functional gray matter structures and neural circuits in the chicken visual system. J. Comp. Neurol. 470:240-255, 2004.

Animals↗
PubMed2004

Multiple binge alcohol consumption during rat adolescence increases anxiety but does not impair retention in the passive avoidance task.

We investigated the effect of binge alcohol consumption on anxiety-related behavior and memory in adolescent male Wistar rats. Three consecutive daily sessions of ethanol administration (5 g/kg) were repeated weekly for 4 weeks. The retention of passive avoidance was measured weekly, 48 h following the treatment. Three days after the last memory test a novel object exploration test was done. There was no significant difference in step-through latency between the groups, but the ethanol-treated group displayed a significantly higher incidence of defecation, and an increased number of boluses during the passive avoidance test. The latency to explore a novel object was also higher, while the duration of exploration was significantly lower. Together, these data suggest that binge alcohol consumption in adolescent rats does not impair their memory in passive avoidance tasks, but may significantly increase their anxiety.

Age Factors↗
PubMed2003

Expression of the genes GAD67 and Distal-less-4 in the forebrain of Xenopus laevis confirms a common pattern in tetrapods.

We investigated whether gamma-amino butyric acidergic (GABAergic) cell populations correlate positionally with specific Dlx-expressing histogenetic territories in an anamniote tetrapod, the frog Xenopus laevis. To that end, we cloned a fragment of Xenopus GAD67 gene (xGAD67, expressed in GABAergic neurons) and compared its expression with that of Distal-less-4 gene (xDll-4, ortholog of mouse Dlx2) in the forebrain at late larval and adult stages. In Xenopus, GABAergic neurons were densely concentrated in xDll-4-positive territories, such as the telencephalic subpallium, part of the hypothalamus, and ventral thalamus, where nearly all neurons expressed both genes. In contrast, the pallium of Xenopus generally contained dispersed neurons expressing xGAD67 or xDll-4, which may represent local circuit neurons. As in amniotes, these pallial interneurons may have been produced in the subpallium and migrated tangentially into the pallium during development. In Xenopus, the ventral division of the classic lateral pallium contained extremely few GABAergic cells and showed only low signal of the pallial gene Emx1, suggesting that it may represent the amphibian ventral pallium, homologous to that of amniotes. At caudal forebrain levels, a number of GABAergic neurons was observed in several areas (dorsal thalamus, pretectum), but no correlation to xDll-4 was observed there. The location of GABAergic neurons in the forebrain and their relation to the developmental regulatory genes Dll and Dlx were very similar in Xenopus and in amniotes. The close correlation in the expression of both genes in rostral forebrain regions supported the notion that Dll/Dlx are among the genes involved in the acquisition of the GABAergic phenotype.

Animals↗