Axotomy-induced retinal ganglion cell death in adult XXXX : quantitative and topographic time course analyses.

@entity2479 @entity19 @entity16159 @entity18489 @entity35
The fate of @entity2479 cells after @entity18489 has been thoroughly described in @entity35 , but not in @entity19 , despite the fact that this species is amply used as a model to study different experimental paradigms that affect @entity2479 cell population. Here we have analyzed, quantitatively and topographically, the course of @entity19 @entity2479 cells loss induced by intraorbital nerve transection. To do this, we have doubly identified @entity2479 cells in all retinas by tracing them from their main retinorecipient area, the superior colliculi, and by their expression of @entity16159 (product of @entity16159 gene). In @entity35 , this transcription factor is expressed by a majority of @entity2479 cells; however in @entity19 it is not known how many out of the whole population of these neurons express it. Thus, in this work we have assessed, as well, the total population of @entity16159 positive @entity2479 cells. These were automatically quantified in all whole-mounted retinas using a newly developed routine. In control retinas, traced- @entity2479 cells were automatically quantified, using the previously reported method (Salinas-Navarro et  al., 2009b). After @entity18489 , though, traced- @entity2479 cells had to be manually quantified by retinal sampling and their total population was afterwards inferred. In na  ve whole-mounts, the mean (  standard deviation) total number of traced- @entity2479 cells was 40,437(  3196) and of @entity16159 positive ones was 34,697(  1821). @entity2479 cell loss was first significant for both markers 5 days post-axotomy and by day 21, the last time point analyzed, only 15% or 12% of traced or @entity16159 positive @entity2479 cells respectively, survived. Isodensity maps showed that, in control retinas, @entity16159 and traced- @entity2479 cells were distributed similarly, being densest in the dorsal retina along the naso-temporal axis. After axotomy the progressive loss of @entity16159 positive @entity2479 cells was diffuse and affected the entire retina. In conclusion, this is the first study assessing the values, in terms of total number and density, of the @entity2479 cells surviving axotomy from 2 till 21 days post-lesion. Besides, we have demonstrated that @entity16159 is expressed by 85.6% of the total @entity2479 cell population, and because @entity16159 positive @entity2479 cells show the same spatial distribution and temporal course of degeneration than traced ones, @entity16159 is a reliable marker to identify, quantify and assess, ex-vivo, @entity2479 cell loss in this species.
