Age-related Morphological Changes in the Retina of Cat

The retinae of 4 old cats (12 years,3-3.5 kg) and 4 young cats (1-3 years,2-2.5 kg) were selected.After treated in 4% paraformaldehyde,we applied HematoxylinEosin and Nissl staining to exhibit the structure of the retinae and ganglion cells respectively,and also we used immunohistochemical ABC method to display the distribution of GFAP-immunoreactive (GFAP-IR) cells that were specifically classified as the astrocytes.By microscope we observed the thickness of retinae,counted the numbers of ganglion cells and GFAP-IR cells.Compared with young cats,the retinae in old cats presented a significant decrease in the thickness of total retina,outer nuclear layer,outer plexiform layer,inner nuclear layer,inner plexiform layer as well as an evidently lower density of ganglion cells.Also old cats showed clearly larger number and stronger staining of GFAP-IR cells than did in young cats,and at the same time the GFAP-IR cell bodies and dendrites swelled obviously in old cats.We presume that neurons lose in old cats,which hints that the loss of retinal cells might be of an important factor mediating visual functional declines during senescence.The functional increase of astrocytes may suspend more aging.