Souter, Mark; (1996) The postnatal maturation of the organ of Corti in gerbils. Doctoral thesis (Ph.D.), University College London (United Kingdom).

Text The_postnatal_maturation_of_th.pdf Download (22MB)

Abstract

This thesis describes the postnatal maturation of the peripheral sensory epithelium of hearing, the organ of Corti, and the stria vascularis in gerbils. Morphological studies of the developing organ of Corti from 2 days after birth (DAB) to 20 DAB were carried out using a combination of techniques including freeze fracture; light microscopy; transmission and scanning electron microscopy. Measurements of the responses of the cochlea to acoustic stimulation were carried out from 10 DAB onward, together with measurements of the endocochlear potential (EP). The principal findings presented in this thesis are 1) whilst sensory cell maturation proceeded with a base to apex gradient, the maturation of the supporting cells and basilar membrane began in the middle turn, followed by the basal turn and finally the apical turn; 2) the basilar membrane did not attain mature thickness until 18 DAB; 3) The apicalmost tight junctional region around the neck of outer hair cells (OHC) had a mature conformation by 8 DAB, whilst the basalmost adherens region did not reach maturity until 16 DAB; 4) Intramembane protein particle (IMP) density on the lateral membrane of OHCs reached 87 % of mature values by 12 DAB, whilst the first complete subsurface cisternal layer was not present until 10 DAB. Pillar structures connecting the outermost cisternal layer to the plasma membrane did not appear until 10- 12 DAB; 5) The inner hair cell (IHC) apical junctional region region matured before that of the OHC; 6) The IMP density on the lateral membrane of IHCs reached a peak at 12 DAB before declining to almost mature values by 18 DAB. From 4 DAB onward, large IMPs were found organised in rows. Plaque structures were first seen in small numbers at 8 DAB and only small numbers were found at 16 DAB; 7) Gap and tight junctional specialisations of the basal cells of the stria vascularis were found to mature with a time course similar to the onset and maturation of the EP, suggesting these cells play a major role in the establishment and maintenance of the EP. The findings are discussed in relation to current opinion on the role of the outer hair cells in maintaining cochlear sensitivity and frequency selectivity and models of the mechanism of production of the endocochlear potential.

Download activity - last month

Export as JSONXMLCSV

Download activity - last 12 months

Export as JSONXMLCSV

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item