Genoarchitectonic Compartmentalization of the Embryonic Telencephalon: Insights From the Domestic Cat

Abstract

The telencephalon develops from the alar plate of the secondary prosencephalon and is subdivided into two distinct divisions, the pallium, which derives solely from prosomere hp1, and the subpallium which derives from both hp1 and hp2 prosomeres. In this first systematic analysis of the feline telencephalon genoarchitecture, we apply the prosomeric model to compare the expression of a battery of genes, including Tbr1, Tbr2, Pax6, Mash1, Dlx2, Nkx2-1, Lhx6, Lhx7, Lhx2, and Emx1, the orthologs of which alone or in combination, demarcate molecularly distinct territories in other species. We characterize, within the pallium and the subpallium, domains and subdomains topologically equivalent to those previously described in other vertebrate species and we show that the overall genoarchitectural map of the E26/27 feline brain is highly similar to that of the E13.5/E14 mouse. In addition, using the same approach at the earlier (E22/23 and E24/25) or later (E28/29 and E34/35) stages we further analyze neurogenesis, define the timing and duration of several developmental events, and compare our data with those from similar mouse studies; our results point to a complex pattern of heterochronies and show that, compared with the mouse, developmental events in the feline telencephalon span over extended periods suggesting that cats may provide a useful animal model to study brain patterning in ontogenesis and evolution.

Characterization of the Abracl-Expressing Cell Populations in the Embryonic Mammalian Telencephalon

“…Feline ( Felis catus ) embryos were obtained from clinically healthy domestic cats referred to the Unit of Obstetrics & Surgery of the Companion Animal Clinic of the School of Veterinary Medicine (Faculty of Health Sciences, Aristotle University of Thessaloniki) for preventive ovariohysterectomy. Staging of the feline embryos was performed as described in [ 14 ]. In brief, gestational age was initially assessed during the presurgical physical examination, as well as by macroscopic examination of the gravid uterus.…”

Critical test of the assumption that the hypothalamic entopeduncular nucleus of rodents is homologous with the primate internal pallidum

“…The traditional entopeduncular/inner GP homology concept needs re-evaluation because it has not been corroborated by comparative neuroanatomy (e.g., Medina, 2007Medina, , 2009Medina & Abellán, 2012;Medina et al, 2005Medina et al, , 2014Reiner, 2016;Reiner et al, 1998Reiner et al, , 2004Reiner et al, , 2005Stephenson-Jones et al, 2011;Ericsson et al, 2012) and because there is consensus in this scientific field that the main details of forebrain structure of all mammals coincide in relative topological positions, genetic background, and developmental origin (reviews in Heimer et al, 1995;Medina & Abellán, 2012;Medina et al, 2014;Paxinos & Watson, 2014;Siskos et al, 2021;Striedter & Northcutt, 2020;Swanson, 2003). Our analysis explores the historic background out of which this confusing comparative opinion seems to have arisen, and then critically examines the scenario in the light of modern genoarchitectural data and some hodological data.…”