Transient Photoreceptor Phototropism in Developing Mouse Retina

This work focuses on quantifying the response of mouse rod photoreceptors to a light stimulus during developmental ages. The purpose is to have a better comprehension of the physiological mechanisms underlying transient retinal phototropism. The three considered post-natal ages are 15, 17 and 19. During this period the increase of ROS length and rhodopsin concentration reaches its peak thus, I expected to see an associated increase in the amplitude of the phototropism elicited by the light stimulus. In particular, rhodopsin is suspected to be a key molecule as far as concern this phenomenon but its role is still unclear. The observation of mouse rod photoreceptors was achieved with Near-Infrared light microscopy, which allowed to have a clear image of the freshly isolated mouse retinae. The images where acquired at 100 fps and they showed a visible movement in response to the light stimulus. The results of the data analysis showed that the amplitude of the movement had a sharp increase between 15 and 17 PN days, while the difference between 17 and 19 PN days was statistically irrelevant. This results were consistent with expectations, as the peak of the growth of ROS has a sharper rise during the first two considered ages. The almost indistinguishable difference between 17 and 19 PN days may depend on the fact that the variables are already saturating to the adult value.