Melanocytes of the Vestibular Labyrinth and Their Relationship to the Microvasculature

Abstract

The melanocytes of the vestibular labyrinth as seen in colored guinea pigs show a characteristic pattern of distribution in the wall of the utricle and in the ampullae, but they are not present in the wall of the saccule. They are found mainly in well-vascularized regions of apparent secretory or metabolic importance, including the "dark cell" areas. Their dendrite-like processes are often in intimate contact with the capillaries, although no pinocytotic vesicles or other indications of transfer of substances between the melanocytes and the capillary endothelium are seen under the electron microscope. In the human ear, the apparent density of the melanocytes varies with skin color. They are numerous in the cochlea, especially in the bony wall of the modiolus and on the osseous spiral lamina, and they occur also in Reissner's membrane and in the stria vascularis. In the vestibular system they are found in the wall of the saccule as well as in the utricle, the crus commune, and the ampullae, but not in the semicircular canals. They tend to be diffusely scattered, rather than to fonn the well-defined, intensely pigmented areas that are characteristic of the guinea pig. Close contacts with capillaries are seen mainly in the tympanic portion of the spiral ligament. The significance of melanin and the melanocytes in the labyrinth is unknown, but both the anatomical relation of certain melanocytes to capillaries, and the biocheInical relation of melanin to the catecholamines support the hypothesis that they may have a vasomotor function. Other evidence, including the not infrequent association of sensorineural deafness with hereditary disorders of pigmentation also suggests that the melanocytes may play a role of some biological consequence in the inner ear.

Effects of Chronic Furosemide Treatment and Age on Cell Division in the Adult Gerbil Inner Ear

“…3A), spiral ligament, modiolus, osseous spiral lamina, macula, ampulla, and semicircular canals and around the endolymphatic duct and sac in all three groups. Similar results have been seen for most other pigmented mammalian species (Wolff 1931;Savin 1965;La Ferriere et al 1974;Hilding and Ginzberg 1977;Franz et al 1990;Gratton and Wright 1992). There was a significant increase of melanin pigment in the stria vascularis, spiral ligament, and maculae of the aged inner ear (data not shown).…”

Distribution and features of melanocytes during inner ear development in pigmented and albino rats

“…The distribution of melanocytes in the modiolus and vestibular partition agreed very well with that reported in other species (Wolff, 1931;Kimura, 1969;LaFerriere et al, 1974;Franz et al, 1990) and no difference was observed between the distribution of melanocytes in pigmented and albino animals. In contrast to the strial melanocytes, they showed the same character istics as skin melanocytes in both strains.…”

“…There is a close correlation b e tween the distribution of pigmented cells and dark cells and they are separated from the dark cells by a basal lamina (Kimura, 1969;LaFerriere et al, 1974).…”

Portadores de vitiligo: estudo das emissões otoacústicas e efeito de supressão

“…3 There are many melanocytes in the human cochlea, particularly in the modiolus, in the osseous spiral lamina, in Reissner's membrane and in the vascular stria; melanocytes are found especially in highly vascularized areas of apparently important secretory or metabolic function. [3][4][5] Although its exact role -and that of melanin -remains unknown, it is probable that they have a vasomotor function in the inner ear. 3,4 According to Savin (1965) The inner ear contains many melanocytes, particularly in the basal area of the cochlea, which is responsible for high sound frequencies, those that are affected earlier by ototoxic drugs and intense noise exposure.…”

“…[3][4][5] Although its exact role -and that of melanin -remains unknown, it is probable that they have a vasomotor function in the inner ear. 3,4 According to Savin (1965) The inner ear contains many melanocytes, particularly in the basal area of the cochlea, which is responsible for high sound frequencies, those that are affected earlier by ototoxic drugs and intense noise exposure. 4,6,7 Conlee et al (1995) studied the effect of gentamicin in animals and concluded that melanin could inhibit the toxicity of these drugs by binding to them; melanin would thus have a protective role for the cochlea.…”