Influence of gamma irradiation on developing otoconia

Thirty-two CBA/CBA mice were irradiated in utero on the 12th, 13th, or 16th gestational day with doses of 0.5, 1, and 2 Gy, respectively (1 Gy = 100 rads). One month after birth, the inner ears were examined by light microscopy and transmission and scanning electron microscopy. Otoconia with defective shapes was identified frequently. The strict hexagonal shape of normal otoconia seldom developed and, in exposed animals, had often been replaced with rounded, oval, or elongated shapes. The otoconial substructure was disarrayed, and fusion of two or three otoconia occurred. Degenerating otoconia appeared in the intercellular space of the dark-cell epithelium. Fetal gross structures of otoconia persisted into maturity.     

Intraluminal crystalloids in malignant salivary gland tumors (electron microscopic and X-ray microanalytic studies)

The ultrastructural, X-ray microanalytical, histochemical and immunocytochemical features of intraluminal crystalloids found in adenocarcinomas of the parotid gland have been studied. The crystalloids, putatively derived from an abnormal crystalization of salivary duct proteins, are considerably different from the crystalloids found in normal parotid glands, pleomorphic adenomas, and sialocysts.     

Morphometry of otoconia in the utricle and saccule of developing Japanese quail

The development of otoconia in the utricular and saccular maculae from initial embryonic formation to adult stages was examined in Japanese quails. Both the morphology and size of the otoconia were quantified at different developmental stages. It was observed that the otoconia were initially formed on embryologic stage E5 in the saccule and E6 in the utricle. Otolith mass areas increased in a sigmoidal growth pattern, with saccular otolith areas being smaller than the utricular mass areas. Saccular otolith masses reached adult values at embryonic stage E12 and utricular areas reached adult values at post-hatch day 7. Mature individual otoconia were characterized by a barrel shape with two trihedral faceted ends. However, initial formation of otoconia at E5 (saccular) and E6 (utricular) maculae was characterized by a double fluted morphology that consisted of an hourglass shape with extended fins forming trihedral angles of 120 degrees. Double fluted otoconia rapidly filled, so that by embryonic day 8 mature otoconia dominated the maculae for the remainder of development through adulthood. Thus, a progression from double fluted to mature forms was noted. Mature utricular otoconia in adult quails averaged 11 microm in length and 5 microm in width, with length/width ratios of approximately 2.5:1, for all size ranges. Saccular otoconia were smaller, having about 70% the size of utricular otoconia in both length and width. During development, the average size and range of individual otoconia increased nearly linearly for both otolith organs. In the utricular macula, large otoconia were concentrated in the lateral regions of the epithelium. In contrast, otoconia of various sizes were distributed uniformly across the surface of the saccular macula.     

Age-related changes on the morphology of the otoconia

OBJECTIVES/HYPOTHESIS: Although there are numerous reports on otoconial morphology using field-emission scanning electron microscopy (FESEM), there are few reports regarding the changes of otoconial morphology with aging. The aim of the current study was to investigate changes in otoconial morphology in rats according to age, using FESEM. STUDY DESIGN: Laboratory study using experimental animals. METHODS: We investigated age-related changes in otoconial morphology using FESEM in three groups of rats: young (1 wk old), middle-aged (6 mo old), and aged (23 mo old). RESULTS: There was great size variation in utricular otoconia in the young and aged rats, but we found no clear regional separation of saccular otoconia in all groups based on size. In the oldest rats, the bodies of many otoconia in both maculae were pitted, fissured, penetrated, and eventually broken into several fragments. However, the terminal facets were smooth and the lines of intersection of facets were sharp, despite the degenerated bodies of the otoconia in this group. Giant otoconia were discovered frequently on the outer margin of the utricular maculae in aged rats. We directly observed weakened or broken linking filaments and otoconial fragments in the aged group. CONCLUSION: The oldest rats showed the most degeneration of otoconia and linking filaments with otoconial fragments. This study of age-related morphologic changes in otoconia might help us understand the origin of idiopathic benign paroxysmal positional vertigo.     

Comparative crystallography of vertebrate otoconia

Otoconial material was obtained from a number of vertebrates to determine the CaCO3 polymorph present. Otoconia and otoliths from bony fish, amphibians, and reptiles are primarily aragonitic; those from birds and mammals are calcitic. This paper summarizes data from all other investigators as well as presenting new data, particularly pertaining to reptiles. The significance, if any, of the relationship between taxonomic group and carbonate polymorph remains an intriguing question.     

Presbyvertigo-aging of otoconia and vestibular sensory cells

Imbalance is a common clinical problem in elderly persons. Subsequently falls and fractures may occur. Age-related balance problems constitute an underestimated but prominent public health problem and a socioeconomic burden. At the histological level the peripheral vestibular system in animals and humans exhibits a variety of age-related changes. The number of otoconia in the utricule and the saccule is reduced with increasing age. Degenerated otoconia caused by aging showed distinct changes of the shape. Moreover age-related decreasing hair cell counts, lipofuscin inclusions and deformation of cilia are observed in human vestibular sensory and supporting cells. Results of vestibular function testing of age-related balance disorders still remain controversially. Regular balance training and vestibular rehabilitation results in less more falls and imbalance.     

Ultrastructural changes in otoconia of osteoporotic rats

The etiology of benign paroxysmal positional vertigo (BPPV) remains obscure in many cases and women are affected more often than men. A recent prospective study, performed in women >50 years of age suffering from recurrent BPPV, showed associated osteopenia or osteoporosis in a large percentage of these patients. These results suggested the possible relationship between recurrent BPPV and a decreased fixation of calcium in bone in women >50 years. To test this hypothesis, an experimental study was performed in adult female rats. Utricular otoconia of female rats in which osteopenia/osteoporosis was induced by bilateral ovariectomy (OVX) were compared to those of sham-operated adult females rats (SHAM), as control group. FIRST STUDY: The morphology of theutricles of OVX and SHAM rats was analyzed with scanning electron microscopy. In osteopenic/osteoporotic rats, the density of otoconia (i.e. the number of otoconia per unit area) was decreased (p = 0.036)and their size was increased (p = 0.036) compared to the control group. SECOND STUDY: To test the role of calcium turnover in such morphological changes, utricular otoconia of 2 other groups of OVX and SHAM rats, previously injected with calcein subcutaneously, were examined by conventional and epifluorescence microscopy. In epifluorescence microscopy, labeling with calcein showed no significant fluorescence in either group. This finding was interpreted as a lack of external calcium turnover into otoconia of adult female rats. The ultrastructural modifications of otoconia in osteopenic/osteoporotic female adult rats as well as the role of estrogenic receptors in the inner ear are discussed. The possible pathophysiological mechanisms which support the relationship between recurrent BPPV in women and the disturbance of the calcium metabolism of osteopenia/osteoporosis are debated.     

Magnesium as an intrinsic component of human otoconia

Objectives: To investigate morphology changes of artificial otoconia (CGC) in the presence of magnesium during growth under in vitro conditions.

Methods: Investigating human otoconia by environmental scanning electron microscope and determining their magnesium content by energy-dispersive X-ray microanalysis (EDX). Comparing structural and morphological data of human and artificial otoconia (CGC, Ca₁Mg₀) without and with magnesium substitution (Ca_1-xMg_x).

Results: EDX- and X-ray data reveals that the inorganic component in human otoconia consists of calcite containing a minor amount of magnesium substitution (Ca_1-xMg_x). CGC containing magnesium (length 397.0?±?146.4?µm, diameter 325.6?±?100.1?µm) are slimmer and significantly smaller (p?p?Conclusions: Magnesium is an intrinsic component of human otoconia by partial substitution of calcium in the calcite crystal structure (Ca_1-xMg_x) and affects the development of the shape of artificial otoconia (calcite gelatin composites, CGC).     

A re-examination of otoconia from the Shaker mouse

We have studied saccular and utricular otoconia from Shaker-1 and Shaker-2 mice by X-ray diffraction and scanning electron microscopy. In contrast to previous reports, we found that the crystals were composed of calcite rather than polycrystalline hydroxylapatite. These crystals were indistinguishable mineralogically and morphologically from normal mouse otoconia. The reported occurrence of hydroxylapatite otoconia in the Shaker mouse is probably false.     

A re-examination of otoconia from the Shaker mouse

Summary We have studied saccular and utricular otoconia from Shaker-1 and Shaker-2 mice by X-ray diffraction and scanning electron microscopy. In contrast to previous reports, we found that the crystals were composed of calcite rather than poly crystalline hydroxylapatite. These crystals were indistinguishable mineralogically and morphologically from normal mouse otoconia. The reported occurrence of hydroxylapatite otoconia in the Shaker mouse is probably false.     

三维滚轮耳石复位系统及其临床应用

目的 观察三维滚轮耳石复位系统治疗良性阵发性位置性眩晕的临床效果.方法 回顾性分析40例后半规管和水平半规管良性阵发性位置性眩晕患者的临床资料,其中20例采用三维滚轮耳石复位系统进行复位治疗,20例采用手法复位治疗,对其疗效进行比较.结果 采用三维滚轮耳石复位系统治疗的患者中第1次治疗后有17例(85%)治愈,3例经过第2次治疗痊愈;采用手法复位的患者中第1次治疗后有16例(80%)治愈,4例经过第2次治疗痊愈.应用x2检验二者的差异没有统计学意义.结论 应用三维滚轮耳石复位系统治疗良性阵发性位置性眩晕临床效果可靠,弥补了手法复位的缺陷,效果直观,可重复性强.     

Microanalytic and light microscopic studies on the developing otic capsule

The structure of the middle layer of the bone of the otic capsule is histologically unique: it is of endochondral origin, has no Haversian canals and the ossification develops from several centres which fuse to form the hardest bone in the body. Our study has been concentrated on the development of the otic capsule in the CBA/CBA mouse, followed from the 13th gestational day to early postnatal age. In the 14th gestational day inner ear, a condensation of mesenchyme is detected around the membranous labyrinth. A cartilaginous capsule is present on the 15th-16th gestational day. Prior to birth, ossification centres occur close to the stapedial footplate. Serial cryosectioning of the newborn inner ear reveals very few regions containing high levels of calcium (microprobe analysis) although by light microscopy, several ossification centres can be identified.     

SEM observations on development of human otoconia during the first trimester of gestation

The early development of human otoconial membranes was studied by scanning electron microscopy and X-ray microanalysis; 87 specimens, ranging from 7 to 12 weeks gestational age were examined. A few otoconia, which contained calcium, were present in the utricle by the end of the seventh week. By 8 weeks, both the saccule and utricle contained otoconia and differentiation of the macular neuroepithelia was well underway. At all stages, the utricular otoconia appeared more mature and were more varied in size and shape than saccular otoconia. In 12-week specimens, the maculae were covered by otoconial membranes with clearly defined crystalline and gelatinous layers. Near the end of the first trimester, newly-formed otoconia were present on the inferior utricular wall. X-ray analysis showed that a marked increase in otoconial calcium content occurs during the period from 7 to 12 weeks gestational age.     

A study of otoconia of normal mice and shaker mice

Otoconia from the maculae of the utricule and the saccule of normal mice and shaker mice have been examined by means of polarizing microscopy and scanning electron microscopy. X-ray dispersive analysis was used to determine the elements present in the crystals. The otoconia were found to be negative birefringent crystals. They are among the largest crystals found in mammalian tissues, many being 30-50 microns in length and 109-20 microns in diameter. The majority were calcite (calcium carbonate) crystals. Some crystals had a different morphological appearance and contained phosphorus (phosphate compound) as well as calcium. The phosphate content was much less and sometimes absent from utricular otoconia of shaker mice.     

Crystallographic and chemical composition of otoconia in the salamander Pleurodeles waltl.

The aim of the present study was to define the morphology and the crystallographic and chemical composition of otoconia in different regions of the inner ear in Pleurodeles waltl (urodele amphibian). The inner ear of adults was microdissected and otoconia were analyzed by scanning electron microscopy (SEM), X-ray diffraction, energy dispersive X-ray (EDX) and transmission electron microscopy. Two types of crystals were detected by SEM. Otoconia had different shapes depending on their location in the membranous labyrinth. One type had a cylindrical body with a triplanar smooth facet at each end, the other ones had either a prismatic shape with flat sides and end faces or a fusiform shape with rounded body and pointed end. The forms corresponded to those previously identified by other authors. These two types of otoconia had different X-ray diffraction patterns. The cylindrical otoconia were calcitic and located in the utricle, the other ones were aragonitic and located in the saccule, lagena and endolymphatic sac. An analysis by EDX indicated that both types of otoconia contained about 95% calcium with trace quantities of sodium, magnesium, phosphorus, sulfur, chlorine and potassium. Trace amounts of strontium was only found in the aragonitic otoconia.     

Glucuronic acid-containing glycosaminoglycans occur in otoconia: cytochemical evidence by hyaluronidase-gold labeling.

Localization of glucuronic acid-containing glycosaminoglycans in the gerbil utricle was examined, using a hyaluronidase-gold labeling technique with special emphasis on the otoconia. Otoconia and the gelatinous layer of the otoconial membrane were strongly labeled by hyaluronidase-gold. The secretory granules in supporting cells were also strongly labeled, suggesting that the organic matrix of otoconia is secreted from the supporting cells. Otoconia seem to lose labeling while they degenerated. The degenerating otoconia were observed to be absorbed into dark cells. Glucuronic acid-containing glycosaminoglycans occur in otoconia. These glycosaminoglycans may play a crucial role in the formation and degeneration of otoconia.     

Appearance and evolution of calcitic and aragonitic otoconia during Pleurodeles waltl development.

The aim of this study is to determine the stages of appearance, morphology, crystallographic structure and chemical composition of otoconia during the inner ear development of an urodele amphibian, Pleurodeles waltl. The first otoconia are detected in the otocyst. Near hatching, calcitic otoconia are polyhedral in the saccule and cylindrical in the utricle. During the following stages, the saccular otoconia agglomerate and constitute a polyhedral calcitic otolith. At larval stage 44, aragonitic fusiform otoconia appear on the otolithic surface. At stage 52, X-ray diffraction analysis shows calcite and aragonite patterns. In adults, all the saccular otoconia are aragonitic. In contrast, the utricular otoconia do not show any modification up to adulthood. In the endolymphatic sac, otoconia appear at stage 45 and in the lagena at stage 49. They remain aragonitic up to adulthood. Energy dispersive X-ray spectroscopy (EDXS) elemental analysis of the otoconia reveals a high quantity of calcium with trace quantities of sodium, magnesium, phosphorus, sulfur, chlorine and potassium. However, magnesium and sulfur have a lower concentration in lagenar aragonitic otoconia than in utricular and saccular calcitic ones. As in adults, trace amounts of strontium are only found in aragonitic otoconia.