Embryonic genoarchitecture of the pretectum in Xenopus laevis: A conserved pattern in tetrapods

Abstract

Networked gene activities control the evolutionarily conserved histogenetic organization of the central nervous system of vertebrates. Genoarchitectonic studies contribute to the analysis of each morphogenetic field by identifying distinct progenitor domains and corresponding derivatives whose pattern of gene expression shows a unique combinatory code. Previous studies in the pretectal region (caudal diencephalon) have defined three anteroposterior genoarchitectonic domains that are conserved in birds and mammals. Here, we have studied the embryonic pretectal genoarchitecture in the amphibian Xenopus laevis, in order to determine whether it is possible to define a comparable anteroposterior tripartition of the amphibian pretectal area. The expression patterns of 14 genes mapped from early embryonic stages to metamorphic climax allowed us to define the boundaries of the pretectum, the expected precommissural, juxtacommissural, and commissural anteroposterior domains, and some dorsoventral subdivisions. Taken together, our data provide evidence for a conserved pattern of pretectal domains and subdomains, shared by amniotes and amphibian anamniotes (tetrapods), understandable as part of a general Bauplan in vertebrates.

Localization of Calbindin-D28k and Calretinin in the Brain of Dermophis Mexicanus (Amphibia: Gymnophiona) and Its Bearing on the Interpretation of Newly Recognized Neuroanatomical Regions

“…A main trait of the distribution of these proteins in the diencephalon is the abundant presence of CR in thalamic neurons in anamniotes [present results;Pombal and Puelles, 1999;Díaz-Regueira and Anadón, 2000;Milán and Puelles, 2000;Castro et al, 2006], whereas in amniotes CB prevails in the thalamus [Braun, 1990;Pritz and Stritzel, 1991;Pritz and Siadati, 1999;Dávila et al, 2000;Münkle et al, 2000;. Within the alar part of p1, the distribution of CB and CR in Dermophis seemed to match well with the 3 molecularly distinct anteroposterior domains already recognized in several vertebrate groups [Pombal and Puelles, 1999;Dávila et al, 2000;Milán and Puelles, 2000;Ferrán et al, 2007;Morona et al, 2011]. The large size and distinct organization of the pretectal region of Dermophis was particularly striking because this region was associated with optokinetic reflexes in amphibians [Cochran et al, 1984;Manteuffel et al, 1986;Sperl and Manteuffel, 1987;Bonaventure, 1992, 1997] that in Dermophis are supposed to be reduced due to the minimized visual system [Himstedt and Manteuffel, 1985;Milner, 2001].…”

Immunohistochemical Localization of DARPP-32 in the Brain of Two Lungfishes: Further Assessment of Its Relationship with the Dopaminergic System

“…The pretectal region of lungfishes houses a small DARPP-32-ir cell population within the commissural nucleus identified in anurans [Morona et al, 2011. Also, in the pretectum of anuran amphibians a small number of DARPP-32-ir cells were observed in the commissural and juxtacommissural pretectal nuclei , whereas amniotes and zebrafish lack DARPP-32-ir pretectal cells.…”

Principles of Current Vertebrate Neuromorphology

“…6 ). The extensive comparative genoarchitectonic studies of Ferran et al [2007Ferran et al [ -2009, Morona et al [2011Morona et al [ , 2017, and Puelles and Ferran [2012] have shown that in the clawed toad Xenopus leavis , the chick, and the mouse the primary FMU, i.e., the pretectum (P), differentiates during early ontogenesis into three rostrocaudally arranged secondary FMUs designated as the precommissural pretectum (PcP), the juxtacommissural pretectum (JcP), and the commissural pretectum (CoP) ( Fig. 7 A, B).…”