摘要:

AbstractIn this paper, the evolutionary origin of the vomeronasal system as a discrete sensory system separate from olfaction is examined. The presence of a discrete vomeronasal system appears to be a derived character in tetrapods, and its presence in larval amphibians indicates that the system did not arise as a terrestrial adaptation. The vomeronasal system has been lost independently in several taxa, including crocodilians, some bats, cetaceans, and some primates. The presence of microvillar receptor cells in the vomeronasal epithelium appears to be the ancestral condition for tetrapods, and alternative hypotheses concerning the ancestral condition for receptor cell types in the vertebrate olfactory epithelium are discussed. Finally, the possibility that the vomeronasal system is present in some fishes in a form that has not been recognized is discussed in relation to the phylogenetic distribution of receptor cell types in vertebrates. © 1992 Wiley‐Liss, I

ISSN:1059-910X    

DOI:10.1002/jemt.1070230102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe used scanning (SEM) and transmission (TEM) electron microscopy to examine ultrastructural changes in the olfactory epithelium (OE) of rainbow trout following unilateral olfactory nerve section. Both ciliated receptor cells (CRC) and microvillar receptor cells (MRC) degenerated and subsequently differentiated from unidentified precursor cells. The following changes took place in fish that were held at 10°C at the stated period following olfactory nerve section: on day 7, MRC and CRC contained intracellular vacuoles; on day 12, the olfactory knobs appeared disrupted; by day 26, olfactory receptor cells were absent from the OE; on day 42, there were receptor cell bodies and a few CRC with short cilia at the apical surface; and opn day 55, a small number of both CRC and MRC had differentiated. By day 76, both CRC and MRC repopulated the OE. Degenerative changes in the cytoplasm of the sustentacular cells (SC) and ciliated nonsensory cells (CNC) were observed in the first 26 days following olfactory nerve section, but these cells remained intact throughout the experiment. The degeneration and subsequent differentiation of CRC and MRC supports and extends previous observations that both cells types are olfactory receptor neurons with axons that extend along the olfactory nerve to the olfactory bulb. © 1992 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070230103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes four investigations of the olfactory mucosa of the brown trout: 1) the ultrastructure of the olfactory mucosa as revealed by scanning (SEM), conventional transmission (TEM), and high voltage (HVEM) electron microscopy; 2) light and electron‐microscopic investigations of retrograde transport of the tracer macromolecule horseradish peroxidase (HRP) when applied to the cut olfactory nerve; 3) SEM and TEM investigations of the effects of olfactory nerve transection on cell populations within the olfactory epithelium; and 4) ultrastructural investigations of reversible degeneration of olfactery receptors caused by elevated copper concentrations. The trout lofactory epithelium contains five cell types: ciliated epithelial cells, ciliated olfactory receptor cells, microvillar olfactory receptor cells, supporting cells, and basal cells. The ciliated and microvillar olfactory receptor cells and a small number of basal cells are backfilled by HRP when the tracer is applied to the cut olfactory nerve. When the olfactory nerve is cut, both ciliated and microvillar olfactory receptor cells degenerate within 2 days and are morphologically intact again within 8 days. When wild trout are taken from their native stream and placed in tanks with elevated copper concentrations, ciliated and microvillar cells degenerate. Replacement of these trout into their stream of origin is followed by morphologic restoration of both types of olfactory receptor cells. Ciliated and microvillar receptor cells are primary sensory bipolar neurons whose dendrites make contact with the environment; their axons travel directly to the brain. Consequently, substances can be transported directly from the environment into the brain via these “naked neurons.” Since fish cannot escape from the water in which they swim, and since that water may occasionally contain brain‐toxic substances, the ability to close off—and later reopen—this anatomic gateway to the brain would confer a tremendous selective advantage upon animals that evolved the “brain‐sparing” capacity to do so. Consequently, the unique regenerative powers of vertebrate olfactory receptor neurons may have their evolutionary origin in fishes. © 19

ISSN:1059-910X    

DOI:10.1002/jemt.1070230104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractHuman olfactory epithelium is similar in organization and cell morphology to that of most vertebrate species. The epithelium has a pseudostratified columnar organization and consists of olfactory neurons, supporting and basal cells. Near the mucosal surface there are also microvillar cells. These cells have neuron‐like features and may be chemoreceptors. Human olfactory epithelium is not a uniform sensory sheet. Patches of non‐sensory tissue often appear in what was thought to be a purely olfactory region. The significance of these patches has not been determined, but they could reflect exposure to environment agents or changes that occur during the normal aging process.In order to better understand the human olfactory system, further knowledge of the normal structure is necessary. This review addresses the morphology of the human olfactory epithelium and the remarkable plasticity of the vertebrate olfactory system. © 1992 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070230105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe present study uses mainly scanning electron microscopy to demonstrate the three‐dimensional internal cell structures of rat olfactory epithelial cells. The aldehyde‐prefixed osmium‐DMSO‐osmium (AODO) method devised by Tanaka and Mitsushima (1984) was applied to the present study to disclose intracellular structures such as endoplasmic reticulum, mitochondria, Golgi apparatus, and lysosomes. The spatial distribution pattern of these structures in olfactory and supporting cells is discussed, paying special attention to the formation of lipofuscin‐like granules present in aged rats. © 1992 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070230106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractDespite increasing knowledge about the biophysiology of the human olfactory system, understanding of the development of this pathway in humans lags considerably behind that of other vertebrates. Development studies have largely concentradted on the generation of cell types in the olfactory epithelium during the first trimester, while detailed ultrastructural observations usually describe the adult morphologh. In this review, we have shown that contrary to what has been generally assumed, the surface of the human olfactory epithelium is heterogeneous and that its olfactory nerves differ ultrastructurally from those of other vertebrates studied. The development of the human primary olfactory pathwayis discussed in terms of the appearance of olfactory bulb laminae, synaptogenesis and the expression of specific cell markers, such as the S‐100 protein and olfactory marker protein (OMP). Positive immunohistochemical staining for N‐cadherin in human fetuses suggests that growth ofolfactory axons to their target may be mediated by cell adhesion molecules. The overall data presented here indicate that this pathway develops more precociously in humans than in rodents. Whether this translates also to earlier functional maturity remains to be elecidated. © 1992 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070230107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe vomeronasal and septal olfactory organs are two neurosensory structures in the mammalian nasal septum which are poorly understood relative to the main olfactory system. The vomeronasal organ is a paired, blind‐ending tubular structure that opens rostrally into the nasal cavity in some species and into the incisive ducts in others. When present in mammals, the septal olfactory organ is an island of olfactory mucosa positioned such that it is in the primary air pathway in the caudal portion of the nasal cavity. Mammalian nasal glands, with a diverse histochemical and ultrastructural morphology, secrete a variety of substances onto the mucosal surface. One of these substances, odorant binding protein, localized in bovine nasal glands and lateral nasal glands of rodents may be important in the capture and conveyance of odorant molecules to olfactory receptors. The objectives of this paper are to present original data while reviewing the literature on the ultrastructure of vomeronasal and septal olfactory neuroepithelia, and of vomeronasal, bovine nasal, and lateral nasal glands. Nasal tissues from pigs, calves, and hamsters were prepared for electron microscopy. Neurosensory epithelia of the porcine vomeronasal organ and the hamster septal olfactory organ are similar to that described for the vomeronasal and septal olfactory organs of other mammals. Bovine nasal and rodent lateral nasal glands consist of subregions which differ morphologically; the most abundant acinar cell type in the bovine nasal gland contains lightly electron dense secretory granules while that of the rodent lateral nasal gland contains both small electron dense and large, electron lucent granules. The porcine vomeronasal gland contains numerous small, dense granules of a diverse morphology. © 1992 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070230108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070230109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070230110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070230101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY