X-ray microanalysis of inner ear fluids in the embryonic and newborn guinea pig.

In energy-dispersive histograms, changes in the relative peak intensities were followed, especially C1 and K, which indicate the maturation of endolymph. The maturation of endolymph in the guinea pig occurs prior to birth. In X-ray histograms, distinct peaks for C1 and K, but also for Na, were observed approximately 20 days before (DBB). The lesser relative peak intensities for C1 and K as compared with mature endolymph indicate an immature endolymph composition at this stage of development. The relative peak intensities of C1 and K increased at approximately the 10-DBB stage and showed similar values as at birth.