Meeting Abstract

P3.64  Saturday, Jan. 5  Scaling of spinal cord motor neurons in the Rainbow Trout, Oncorhynchus mykiss FEUERBORN, E *; RODNICK, K; ANDERSON, C; Idaho State University; Idaho State University; Idaho State University andecurt@isu.edu

As an organism increases in size either through development or evolution, the brain must accommodate such changes to successfully coordinate movements. As biological systems increase in size, they either slow down or must account for these relationships between motor neuron size and muscle mass. With any growth or movement, the brain must then account for these allometric changes. Our previous work in toads suggests that there is no statistically significant relationship with motor neuron size and increases in body size. However, there likely was not a large enough size range in the organisms to detect differences in cell size. In this study, we used the rainbow trout, Oncorhynchus mykiss, ranging in size from 2cm to 65cm (0.07g to 3.67kg). Ventral horn motor neurons from three different locations in the spinal cord were measured for linear dimensions as well as soma area. Thus far, data suggest that ventral motor horn neurons increase in size with increasing mass and linear proportions of the fish. This growth pattern of ventral horn motor neurons has a positive allometric relationship, with growth rates slowing as the fish matures. This research is a first step to determining what accounts for the increase of size in the spinal cord, as well as how animals maintain innervation of growing effector organs