Exploration on the underlying mechanism of female predominance in spasmodic dysphonia: an anatomical study of nodose ganglion in rats.

To study the gender differences of amount of neurons in the nodose ganglions of rats. Fourteen Sprague-Dawley rats (7 males and 7 females) were selected. Bilateral nodose ganglions were dissected and serial sections of nodose ganglion were cut in a cryostat, followed by Cresyl-violet staining for neurons. Eight to ten consecutive sections from mid-portion of each nodose ganglion sample, which represent the most neuron number per section, were counted and averaged. Gender difference in the amount of neurons in the nodose ganglions was compared. No gender difference of neuron numbers was found in either side of nodose ganglion (p > 0.05). However, average neuron number of nodose ganglions on the left side of male (654 ± 60) and female (616 ± 37) were significantly more than that on the right side of male (470 ± 22) and female (453 ± 40) respectively (p < 0.05). There is no gender difference in total neuron number of nodose ganglions between male and female rat. However, the neuron number in the left nodose ganglion is greater than that in the right one. The difference may be due to the fact that left and right nodose ganglion is receiving different visceral sensory impulses separately, which is associated with different physiological functions. Further work should be carried out with retrograde tracing on neurons of nodose ganglions in an animal model, which are directly related to laryngeal sensory transmission, in order to determine the gender difference in the neuron number and morphology related to laryngeal functions.