Freeze-fracture studies on unmyelinated axolemma of rat cervical sympathetic trunk: correlation with saxitoxin binding

The density and diameter distributions of intramembranous particles (IMPs) within unmyelinated axolemma from rat cervical sympathetic trunk were examined with freeze-fracture electron microscopy. The axolemma displays a highly asymmetrical partitioning of IMPs with ca. 1200 IMPs microns-2 on P-faces and ca. 100 IMPs microns-2 on E-faces. Particle sizes (diameters) are unimodally distributed on both fracture faces, with a range from 2.4 nm to 15.6 nm. Approximately 16% of the particles on P-faces and 28% of particles on E-faces are of a large (greater than 9.6 nm) diameter. On both fracture faces, the IMPs appear to be randomly distributed; no aggregations of particles were observed. The results indicate that there are ca. 230 large IMPs microns-2 of unmyelinated axolemma from rat cervical sympathetic trunk. The density of these IMPs is similar to the density of saxitoxin binding sites on unmyelinated axolemma from rat cervical sympathetic trunk (Pellegrino et al. 1984 (Brain Res. 305, 357-360)), which suggests that many of the large diameter particles may be the morphological correlate of voltage-sensitive Na+ channels.     

THE C.P.S. ADMINISTRATION

There is no doubt that cancer cells do enter the circulating blood of persons with malignant lesions. Differentiation of them from other atypical cells found normally in the bloodstream is at present being studied.Investigators have expressed belief that most of the circulating malignant cells in the early stages of the disease are destroyed by host resistance. Surviving cells, however, develop into occult metastatic emboli which may remain quiescent until host defenses collapse. Clinical measures for the active control of these dormant implants have not been evolved as yet.Inasmuch as the mechanism of host resistance is still beyond clinical comprehension, the only known way to improve survival rates is the universal application of practical clinical methods for preventing iatrogenic disseminations, for devitalizing malignant cells and for apprehending emboli that may have left the main lesion just before surgical operation.Since it adequately eradicates primary sources of cell dissemination, conventional radical resection is still the treatment of choice for dealing with early solid neoplasms.