Premium
Olfactory bulb and retrobulbar regions in the hedgehog tenrec: Organization and interconnections
Author(s) -
RadtkeSchuller Susanne,
Künzle Heinz
Publication year - 2000
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/1096-9861(20000807)423:4<687::aid-cne12>3.0.co;2-f
Subject(s) - olfactory bulb , biotinylated dextran amine , biology , anatomy , nissl body , olfactory tubercle , anterior olfactory nucleus , olfactory system , piriform cortex , neuroscience , central nervous system , axon , staining , genetics
The Madagascan lesser hedgehog tenrec ( Echinops telfairi ) is a terrestrial, nocturnal insectivore with a low encephalization index and a huge olfactory bulb. To gain insight into the organization and evolution of olfactory regions in placental mammals, the cytoarchitecture (Nissl), neurochemical attributes [zinc and acetylcholinesterase stain, nicotinamide adenine dinucleotide phosphate (NADPh)‐diaphorase, and calcium‐binding proteins], and interconnections (injections of wheat germ agglutinin‐horseradish peroxidase and biotinylated dextran amine) of tenrec bulbar and retrobulbar regions were examined. The tenrec has a well‐laminated main olfactory bulb, and modified (atypical) glomeruli are found that, to date, have been demonstrated only in murine rodents. Compared with the main olfactory bulb, the accessory bulb is relatively small, with clearly different staining characteristics, particularly with respect to NADPh‐diaphorase, anticalbindin, and anticalretinin. External and central anterior olfactory nuclei also show characteristic cytoarchitectural and chemoarchitectural features. The medial olfactory peduncle seems to differ considerably from that in rodents. A small taenial structure can be separated from the hippocampal continuation. This taenia tecti presumably corresponds to the superior part of the tenia tecti in rodents, but no homologue of the rodent's prominent inferior taenia tecti could be found. The connections of bulbar and retrobulbar regions are similar to those seen in other mammals. Interbulbar projection systems connect the two olfactory bulbs through an external (topographic) and central (nontopographic) anterior nucleus; however, the topographic arrangement of the intrabulbar association system seems to differ from that seen in rodents. A reciprocity of direct olfactory bulb connections with the frontal (sulcal/orbital) cortex was found in the tenrec that has not been reported so far in other species. J. Comp. Neurol. 423:687–705, 2000. © 2000 Wiley‐Liss, Inc.