HYPOGLOSSAL NERVE;

NEURONS CONTRIBUTING THE SENSORY FIBERS IN ALBINO RATS- HORSERADISH PEROXIDASE (HRP) STUDY

Abstract

Objective: To study the neurons contributing sensory fibers to the
hypoglossal nerve. Setting: Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre, Karachi. Period:
From 1992 to 1995. Study Design: Experimental animal study. Material & Methods: Under general anaesthesia the
required hypoglossal nerves of twenty four albino rats were exposed and cut in the neck. Horse radish Peroxidase
(HRP) crystals were applied to the central cut ends of the nerves and allowed to travel for about 48 hours. After
transcardial fixation with 1.25% gluteraldehyde and 1% paraformaldehyde solution, serial sections of upper cervical
Dorsal Root Ganglia (DRG) were made on a freezing microtome, treated with Tetramethylbenzidine (TMB) and
counterstained by 1% neutral red. The number, size and segmental distribution of HRP labeled neurons were observed
with the help of light microscope. Results and Observations: In most of the animals, the HRP labeled sensory neurons
forming the right and the left hypoglossal nerves and their branches were localized ipsilaterally in (Cervical) C1 DRG
(more than 90%) whereas in remaining cases labeled sensory neurons were observed in C2 DRG. Size spectrum for
sensory neurons of the hypoglossal nerve and its branches ranged from 9 to 52:m, but more than 75% were less than
40 microns.Conclusion: Neurons of DRG of C1&2 contribute sensory fibers to the hypoglossal nerve of the same side.