Cell renewal in the eustachian tube epithelium of guinea pigs
The turnover time of the epithelial cells of a normal eustachian tube was estimated in guinea pigs by means of lightmicroscopic autoradiography with thymidine-H3.
The cell migration from the basal layer to the tubal lumen was chased by sacrificing the animals at different intervals after thymidine-H administration. This study revealed that the generative cells were the basal cells in the tubal epithelium and that the different types of maturative cells in the epithelium have a different life span. The turnover time of non-ciliated secretory cells was about 145 hrs (about 6 days), while that of ciliated cells and goblet cells more than 6 days.
Available from: PubMed Central
- "It is not clear, however, whether such resorption of cilia is a sign of the beginning of the renewal of the cilia or the cell. Mature cells in the epithelium have a different life span; the turnover time of ciliated cells and goblet cells in guinea pigs is estimated to be six days . "
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ABSTRACT: The Eustachian tube is a small canal that connects the tympanic cavity with the nasal part of the pharynx. The epithelial lining of the Eustachian tube contains a ciliated columnar epithelium at the tympanic cavity and a pseudostratified, ciliated columnar epithelium with goblet cells near the pharynx. The tube serves to equalize air pressure across the eardrum and drains mucus away from the middle ear into the nasopharynx. Blockage of the Eustachian tube is the most common cause of all forms of otitis media, which is common in children. In the present study, we examined the epithelial lining of the Eustachian tube in neonatal and adult gerbils, with a focus on the morphological and functional development of ciliated cells in the mucosa. The length of the tube is ∼8.8 mm in adult gerbils. Scanning electron microscopy showed that the mucosal member near the pharyngeal side contains a higher density of ciliated cells and goblet cells than that near the tympanic side. The cilia beat frequency is 11 Hz. During development, the length of the Eustachian tube increased significantly between postnatal day 1 (P1) and P18. Scanning electron microscopy showed that the mucosa contained a high density of ciliated cells with a few goblet cells at P1. The density of ciliated cells decreased while the density of goblet cells increased during development. At P18, the mucosa appeared to be adult-like. Interestingly, the ciliary beat frequency measured from ciliated cells at P1 was not statistically different from that measured from adult animals. Our study suggests that the Eustachian tube undergoes significant anatomical and histological changes between P1 and P18. The tube is morphologically and functionally mature at P18, when the auditory function (sensitivity and frequency selectivity) is mature in this species.
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