An imaging technique called orthogonal-plane fluorescence optical sectioning (OPFOS) was developed to image the internal architecture of the cochlea. Expressions for the three-dimensional point spread function and the axial and lateral resolution are derived. Methodologies for tissue preparation and for construction, alignment, calibration and characterization of an OPFOS apparatus are presented. The instrument described produced focused, high-resolution images of optical sections of an intact, excised guineapig cochlea. The lateral and axial resolutions of the images were 1 0 and 26 pm, respectively, within a 1.5-mm field of view.

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Multiwavelength optical spectroscopy was used to determine the oxygen-binding characteristics for equine myoglobin. Oxygen-binding relationships as a function of oxygen tension were determined for temperatures of 10, 25, 35, 37, and 40 degrees C, at pH 7.0. In addition, dissociation curves were determined at 37 degrees C for pH 6.5, 7.0, and 7.5. Equilibration was achieved with a myoglobin solution, at the desired temperature and pH, and 16 oxygen-nitrogen gas mixtures of known oxygen fraction. Correction for the inevitable presence of metmyoglobin was made by using a three-component least squares analysis and by correcting the end point oxymyoglobin spectra for the presence of metmyoglobin. The PO2 at which myoglobin is half-saturated with O2 (P50) was determined to be 2.39 Torr at pH 7.0 and 37 degrees C. The myoglobin dissociation curve was well fit by the Hill equation [saturation = PO2/(PO2 + P50)].