Abstract:Objective To measure the actual area of the vestibular sensory area in the inner ear of commonly used experimental animals and quantitatively analyze the hair cells of each sensory area of the vestibule from the perspective of histopathological observation.Methods ①The macula of saccule, macula of utricle, and crista of ampulla were prepared as flat surface preparations in experimental animals of CBA/CaJ mice, nude mice, SD rats, guinea pigs, chinchillas, New Zealand white rabbits and African vervet monkeys. All samples were obtained from 6 temporal bones of each tested animal species. The photographs of each vestibular end-organs were taken under a light microscope at 100X magnification.②Using the ImageJ software, the actual areas of the macula of saccule and the macula of utricle were measured in above seven experimental animals. ③A grid was used to divide the vestibular sensory areas of macula of saccule and macula of utricle on the photos into several square areas. The number of hair cells in each grid was accurately counted under the magnified image, and the hair cell counts in each grid were then summed to obtain the total number of hair cells in the macula of saccule and macula of utricle. ④The hair cell density was also calculated within the small visual field of each sensory area of the vestibule end-organs.Results ①The areas of macula of saccule from CBA/CaJ mice, nude mice, rats, guinea pigs, chinchillas, white rabbits to monkeys were (0.193±0.009), (0.216±0.008), (0.323±0.01), (0.528±0.035), (0.687±0.065), (1.237±0.075), (1.371±0.032)mm2; and the areas of macula of utricle from above animal sequence were (0.193±0.02), (0.208±0.013), (0.321±0.011), (0.526±0.034), (0.795±0.017), (1.224±0.082), (1.388±0.048)mm2; ②The total number of hair cells in the macula of saccule from mouse, nude mouse, rat, guinea pig, chinchilla, white rabbit to monkey were 2 476.3±64.4, 2 389.8±47.8, 3 135.3±191.6, 4 882.2±208.7, 6 128.5±242.9, 10 572.2±464.4, 10 992.7±397.4. The total number of hair cells in macula of utricle from above animal sequence were 2 491.4±54.8, 2 368.0±46.1, 3 218.8±82.9, 4 925.3±271.1, 7 794.0±386.1, 11 347.4±435.7, 11 114.5±410.6; ③The hair cell density (number of hair cells/0.007 mm2) in the striola area and marginal area of saccule in mouse, rat, guinea pig, chinchilla, rabbit and monkey were 101.0±5.79 (in striola region)/120.8±4.15 (in marginal region), 95.5±3.91 (in striola region)/109.2±5.26 (in marginal region),78.4±6.54 (in striola region)/94.8±4.38 (in marginal region),60.0±4.74 (in striola region)/84.6±2.61 (in marginal region),57.2±3.83 (in striola region)/80.0±3.54 (in marginal region),53.8±4.21(in striola region)/68.0±4.18 (in marginal region), respectively. The hair cell density (number of hair cells/0.007 mm2) in the striola area and marginal area of utricle in mouse, rat, guinea pig, chinchilla, rabbit and monkey were 103.8±5.02 (in striola region)/119.2±3.70 (in marginal region),91.2±2.49(in striola region)/106.4±4.16 (in marginal region),74.1±3.54 (in striola region)/90.8±3.56 (in marginal region),60.4±4.98 (in striola region)/81.6±2.07 (in marginal region),57.8±1.92 (in striola region)/77.8±3.70 (in marginal region),54.0±2.74 (in striola region)/66.4±2.51 (in marginal region), respectively. The hair cell density (number of hair cells/0.007 mm2) in the crista of ampulla of mouse, rat, guinea pig, chinchilla, rabbit and monkey were 112.4±6.38, 105.5±3.51, 95.2±3.42, 84.0±7.16, 78.2±2.86, 70.8±2.39. It can be seen that the cell size of hair cells in smaller animals is smaller than that of larger animals, the density of vestibular hair cells in smaller animals is higher than that of larger animals. In addition, the density of hair cells in the striola region between macula of saccule and macula of utricle is similar, and the hair cell density in the marginal region between the macula of saccule and macula of utricle is also quite similar, but the hair cell density in the striola area is lower than hair cell density in the marginal area. Also, the density of hair cells in the ampulla crista was almost identical to that in the marginal areas in both maculae of saccule and utricle. In view of the fact that certain damage factors often have the performance of selectively destroying the hair cells in the striola area of maculae,the hair cell density in the striola area of maculae should be distinguished from the hair cell density in the surrounding marginal zone, and if necessary, even type I hair cells and type II hair cells should be distinguished to quantify the pathological changes respectively.Conclusion The vestibular measurement method used in this study and the measurement data of each sensory area of the vestibule, the total number of hair cells and the density of hair cells provide useful reference experience and necessary reference data for the quantitative analysis of vestibular pathology.