NUMBERS AND DIAMETERS OF MOTONEURONS AND MYELINATED AXONS IN FACIAL NUCLEUS AND NERVE OF ALBINO-RAT

  • 1 January 1977
    • journal article
    • research article
    • Vol. 123  (JUL) , 579-587
Abstract
The number and diameter of motoneurons in serial sections of the facial nucleus in the albino rat were estimated using a photograph-camera lucida technique for counting and measuring cells in conjunction with a systematic section method for sampling the population. The mean diameter of facial motoneuron nucleoli was also estimated. Total cell counts were estimated using 2 formulas, one a basic count and the other the basic count corrected for split nucleoli errors. The mean motoneuron diameter was 33.93 .mu.m (.+-. 6.18 .mu. SD). The number and diameter of myelinated axons in both the facial nerve and its cutaneous auricular branch at the level of the stylomastoid foramen, were estimated. There are 5353 myelinated axons in the facial nerve, with a mean diameter of 2.74 .mu.m, and 627 myelinated axons in the cutaneous auricular branch with a mean diameter of 1.47 .mu.m. The accuracy and reproducibility of results using the photograph-camer lucida technique for counting and measuring cells and the systematic section method of sampling were compared with other methods. The accuracy of resuts obtained for estimates of the total cell count using the formulas for the basic count and the basic count corrected for split nucleoli was also compared.