CHARACTERIZATION OF THE NEUROSENSORY ELEMENTS OR THE FELINE CRANIAL CRUCIATE LIGAMENT

The identification and distribution of mechanoreceptors in the cranial cruciate ligament of the cat (analogous to the anterior cruciate liga ment in other species) was studied histologically using a modified cel loidin embedding technique to achieve serial sectioning of bone-ligame nt-bone preparations with gold chloride staining. We identified distin ctive large elongated structures situated between the collagen bundles of the ligament (resembling endings described as Freeman and Wyke typ e III; also termed Golgi tendon receptors). These endings were found n ear the middle of the ligament well away from the bone-ligament juncti on. Axons seen entering only one end of each type III ending helped to confirm its neural basis. While we saw structures resembling types I and II endings (i.e. Ruffini and pacinian endings, respectively) in in dividual sections, serial sections failed to reveal convincing evidenc e of their existence. Such structures almost always appeared to be vas cular in nature on adjacent sections, with vessels entering and exitin g. We conclude that serial sections are critical to interpreting the p resence or absence of mechanoreceptors.