TRANSMISSION ELECTRON-MICROSCOPE STUDIES AND THEIR RELATION TO POLARIZING OPTICAL MICROSCOPY IN RAT TAIL TENDON

An investigation on rat tail tendon is described which follows the periodic banding pattern seen by the polarizing light microscope down to the level of transmission electron microscopy. This work was carried out by longitudinal sectioning of preselected tendon portions in preselected orientations around the tendon axis. In the course of this, full bridging of light with electronmicroscopic structural information has been achieved. In particular, complete verification is provided for the planar crimp structure as originally postulated from polarizing microscopy. Thus thin sections fully conformed even to the idealized crimp representation when viewed under the polarizing microscope, while the crimp sites themselves could be detected. These were seen to be sharp as implied by the rigid hinge model, which was invoked previously merely as a mathematical convenience to account for the mechanical behaviour. This sharpness of the crimp site persisted down to the level of the 68nm banding visible under the electron microscope and was seen to occur within 1-2 such band periods. Various individual features seen at all levels are discussed. © 1978.