Cochleae from fetal guinea-pigs (37 to 64 gestation days, gd) were used to correlate the
appearance of motile properties of isolated outer hair cells (OHCs) with the development of
specific morphological features. Both the 'fast'electrically-driven and the 'slow'calcium-
induced motilities appeared first in OHCs from basal turn of 52 gd fetuses. At 56 gd, most of
basal and some apical OHCs responded positively to both types of stimulation. All tested
cells were positive at 64 gd. It is noteworthy that this period closely corresponds to the onset …