Comparative Morphology of Rodent Vestibular Periphery. II. Cristae Ampullares

Abstract

We made flattened neuroepithelial preparations of horizontal and vertical (anterior and posterior) cristae from mouse, rat, gerbil, guinea pig, chinchilla, and tree squirrel. Calretinin immunohistochemistry was used to label the calyx class of afferents. Because these afferents are restricted to the central zone of the crista, their distribution allowed us to delineate this zone. In addition to calyx afferents, calretinin also labels approximately 5% of type I hair cells and 20% of type II hair cells throughout the mouse and rat crista epithelium. Measurements of the dimensions of the cristae and counts of hair cells and calyx afferents were determined on all species. Numbers of calyx afferents, hair cells, area, length, and width of the sensory epithelium increase from mouse to tree squirrel. As in the companion paper, we obtained additional data on vestibular end organ dimensions from the literature to construct a power law function describing the relationship between crista surface area and body weight. The vertical cristae of the mouse, rat, and gerbil have an eminentia cruciatum, a region located transversely along the midpoint of the sensory organ and consisting of nonsensory cells. Apart from this eminentia cruciatum, there are no statistical differences between horizontal and vertical cristae with regard to area, width, length, the number and type of hair cells, and number of calretinin-labeled calyx afferents.

K+ Currents in Isolated Vestibular Afferent Calyx Terminals

“…Cup-shaped calyx terminals were observed surrounding the basolateral regions of one and occasionally two or three type I hair cells. This is consistent with observations in fixed tissue from the gerbil crista ampullaris, where most calyces were single, but in some cases contacted up to four type I hair cells (Desai et al 2005). Afferent stalks connected to calyces were almost never observed in isolated terminals.…”

Hair Cell Generation by Notch Inhibition in the Adult Mammalian Cristae

“…Hair cells were counted by continuously scanning through confocal stacks taken at a z interval of 0.5 μm to avoid double counting or missing cells. The hair cell counts in the control cristae are similar to what has been reported previously in adult mice with optical dissector counting (Desai et al 2005b) and in E18.5 mice using confocal slices taken at 6 μm intervals (Fritzsch et al 2010).…”

“…In mice, the anterior and posterior cristae are separated into two hemicristae by a hair cell-free region called the eminentia cruciatum ( Fig. 1(B,D,D′); Desai et al 2005b). The lateral crista does not have an eminentia cruciatum and is instead one continuous sensory structure ( Fig.…”

“…In addition, we found that the lateral crista had significantly fewer hair cells than anterior or posterior cristae (data not shown) and so excluded it from analyses involving hair cell counts. For this study, we used the regional boundaries defined by Desai et al (2005b) where the central zone is the region containing the Calretininpositive calyx afferents that innervate type I hair cells ( Fig. 1(D,D′)) and the remaining sensory region is the peripheral zone.…”

Histopathologic Changes of the Inner ear in Rhesus Monkeys After Intratympanic Gentamicin Injection and Vestibular Prosthesis Electrode Array Implantation

“…Total HC surface density in the cristae and maculae has been shown to decrease with increasing body size, being approximately 120-200/0.01 mm 2 in chinchillas (Fernandez et al 1995;Desai et al 2005a;Desai et al 2005b), 100-130/0.01 mm 2 in squirrel monkeys (Fernandez et al 1995), and 60-80/0.01 mm 2 in humans (Richter 1980;Lopez et al 2005). Although normative data have not been published for the rhesus monkey, the mean total HC estimate of 79/ 0.01 mm 2 (SD 3.0/0.01 mm 2 ) we measured for cristae and maculae of normal rhesus ears in this study is consistent with this trend when compared to human and small animal data obtained using unbiased stereology.…”