Studies On Photo-Sensitivity Of Visual System In Myospalax Cansus

Adaptive evolutionary mechanisms of sensory system are the focal points of the animal behavior research, and especially the conspicuously different features that those animals residing in special ecotope show during the evolution of their sensory system are more attractive. Owning to adapting to subterranean dark ecotope, morphologic structure and functional of visual system in subterranean rodents show high convergence, such as small ocular system, regressive visual ability and even no such ability, which provide ideal materials for the study on visual system evolution of these animal. And it will assist in revealing the adaptive evolutionary mechanism of visual system of subterranean rodents. Using histological and immunohistochemistry method to measure Fos expression content of every visual nucleus in different light stimulation time and different dark adaptation period, and to explore the photo-sensitivity of visual system. The results are as follows:1. Strong Fos expression in dorsal lateral geniculate nucleus after light exposure, which is a strong indication for the light-induced reactivity of neurons within the dorsal lateral geniculate nucleus in Myospalax cansus. And show that Myospalax cansus has the typical pathway from retina, relaying through the dorsal lateral geniculate to primary visual cortex, and the dorsal lateral geniculate nucleus play the role of processing light signal as a part of the image-forming visual system. Little Fos expression in ventral lateral geniculate nucleus after light exposure, which indicate that the ventral lateral geniculate nucleus has little function in transmitting visual signal action in Myospalax cansus.2. No obvious increase in Fos expression in superior colliculus of Myospalax cansus during exposure to light, which indicates in Myospalax cansus with its minute eyes the superior colliculus is no longer needed as a major center of coordination for visuo-ocular reflexes.3. Strong Fos expression in olivary pretectal nucleus and optic tract nucleus after exposure to light in Myospalax cansus, which indicate they involve not only in the integration of visuomotor functions and the pupillary light reflex, but also in dark/light discriminatioin.4. Strong c-Fos expression in suprachiasmatic nucleus after light exposure after some dark adaptation period, which suggests that the rudimentary eyes and retino-.