Olfactory Cilia in the Frog

Abstract

Olfactory epithelium from the frog was examined in the living state by light microscopy and in the fixed statc by electron microscopy. Particular attention was paid to the layer of cilia and mucus which covers the surface of the epithelium. The olfactory cilia differed from typical cilia in that thcy (a) arose from bipolar neurons and had ccntrioles ncar their basal bodies, (b) were up to 200 microns in length, of which the greater part was a distal segment containing an atypical array of ciliary fibers, (c) wcre ohcn immotile, (d) had their distal segments arranged in parallcl rows near the surface of the mucus, and (e) had many vesicles along their shahs and had splits in the array of fibers in their distal segments. These specializations make the olfactory cilia similar to cilia found on other sensory cclls and support the theory that they are the locus where electrical excitation in the olfactory organ is initiated by contact with odorous substances.

An Electron Microscopic Study of the Olfactory Mucosa in the Bat and Rabbit

“…6A) which is, however, indistinct in appearance because of the obscurity of its limiting membrane. A similar vesicle or granule was observed by REESE (1965) in the basal bodies of frog olfactory cilia. In cross sections, basal bodies appear as circular configurations composed of an electron dense peripheral wall or shell and an electron lucent interior or cavity, and in the electron dense wall, 9 triplet tubules are circularly arranged at regular intervals (Fig.…”

“…As pointed out by FRISCH (1964aFRISCH ( , b, 1965FRISCH ( , 1967, REESE (1965), OKANO et al (1967), the proximal thick portion (segment) of olfactory cilia tapers away in a long thin extension, which shows dilations along its long course. These two characteristics of olfactory cilia have also been as ordinary non-sensory motile cilia, and contains a set of 9+2 fibrils (tubules), while in the following long distal thin portion, the 9 peripheral doublet fibrils (tubules) and the 2 central fibrils (tubules) can not be distingished, only a few single tubules being scattered randomly in the matrix.…”

“…BANNISTER (1965) revealed, in an electron microscopic study on the teleostean olfactory surface, the simultaneous occurrence of a usual conical basal foot and the pinwheel-like configuration probably of the spokes in a one and the same cross section of a basal body (see Figure 11 in this paper). REESE (1965) observed, in the basal bodies of the frog olfactory cilia, conical basal feet and pinwheel configurations of transitional fibers (spokes), and he showed them in several electron micrographs.…”

“…As reviewed by GRAZIADEI (1972), olfactory cilia (hairlets) have been electron microscopically investigated in a variety of vertebrates by many authors such as BLOOM (1954), BRETTSCHNEIDER (1958), YASUTAKE (1959), DE LORENZO (1960, REESE (1965), YAMAMOTO et al (1965), ANDRES (1969) and others. As pointed out by FRISCH (1964aFRISCH ( , b, 1965FRISCH ( , 1967, REESE (1965), OKANO et al (1967), the proximal thick portion (segment) of olfactory cilia tapers away in a long thin extension, which shows dilations along its long course.…”

“…The olfactory mucosa, especially the olfactory epithelium, has been studied by many authors with the light (KOLMER, 1972;ALLISON, 1953;BANG and BANG, 1959 etc. ) and electron microscope (REESE, 1965;OKANO, 1965;OKANO et al, 1967;SEIFERT and ULE, 1967;FRISCH, 1967;ANDRES, 1969;GRAZIADEI, 1972 etc.). However, several questions still remain unanswered.…”