Olfactory and amygdalar structures of the chicken ventral pallium based on the combinatorial expression patterns of LIM and other developmental regulatory genes.
We compared the combinatorial expression patterns of several LIM domain-containing regulatory genes in the ventrolateral pallium of mouse and chicken, in order to identify the homologues of the ventral pallial amygdala and other olfactory structures in birds. Lmo3, Lmo4, Lhx2, and Lhx9 showed comparable expression patterns in the telencephalon of mouse and chicken, which allowed distinction of the ventrolateral pallium and, particularly, the ventral pallial amygdala and entorhinal cortex. Lmo3 was expressed in most of the ventrolateral pallium in both species, including, in chicken, the piriform cortex and dorsal ventricular ridge (mesopallium, nidopallium, and arcopallium) and, in mouse, the piriform cortex, most of the claustral complex, and the pallial amygdala. Lhx9 was differentially expressed in the ventral pallium, where it was restricted to its rostral (olfactory bulb) and caudal (amygdalar and entorhinal) poles. In the caudal pole, expression of Lhx9 overlapped that of its paralog Lhx2. According to these expression patterns, the chicken ventral pallial amygdala appears to include the caudal dorsolateral pallium, the caudal nidopallium, and the whole arcopallium, and each one relates to a distinct ventricular sector. Finally, the combinatorial expression patterns of Lmo3, Lhx9, and Lmo4 distinguished four distinct subdivisions in the superficial, olfactorecipient area of the chicken ventral pallium, which appear comparable to the piriform, entorhinal, amygdalopiriform, and amygdalar cortices of mammals. The results are discussed in the context of the two existing, opposite views on the homology of the dorsal ventricular ridge of sauropsids and in terms of the evolution of pallial derivatives.
Abellán
Antonio
A
Laboratory of Brain Development and Evolution, Department of Experimental Medicine, Faculty of Medicine, University of Lleida, Institut of Biomedical Research of Lleida (IRBLLEIDA), 25008 Lleida, Spain.
Legaz
Isabel
I
Vernier
Baptiste
B
Rétaux
Sylvie
S
Medina
Loreta
L
D048868:Adaptor Proteins, Signal Transducing; D000679:Amygdala / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D002642:Chick Embryo / Q000196:embryology / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D060588:LIM Domain Proteins; D060850:LIM-Homeodomain Proteins; D051379:Mice; D055696:Olfactory Perception / Q000235:genetics / Q000502:physiology*; D016133:Polymerase Chain Reaction; D013687:Telencephalon / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D018398:Homeodomain Proteins; D060588:LIM Domain Proteins; D060850:LIM-Homeodomain Proteins; C489784:Lhx2 protein, mouse; C117058:Lhx9 protein, mouse; C491976:Lmo4 protein, mouse; D014157:Transcription Factors