Abstract
Abstract: :
Purpose: To explore the postnatal development of morphology of the mouse retinal ganglion cells, to narrow down on the time window during which the adult morphologies appear and to highlight the possible mechanisms regulating the maturation of the retinal ganglion cells. Methods: C57BL/6N mice at 3 developmental stages, postnatal day 0, 8 and 13 were used in this study. The animals were anesthetized by hypothermia, and then sacrificed by cervical dislocation. The eyeballs were immediately enucleated, submerged in oxygenated Ames and the retinas isolated. To label all cells, the isolated retinas were incubated in Ames solution containing 1 µg/ml DAPI that was constantly bubbled with 95% O2 and 5% CO2 for 1 hour. Four slits were cut in the retina to flatten it, and the DAPI-labeled retina was mounted ganglion cell side up on a black Millipore filter. Then the mounted retina was labeled with DiI using a BioRad PDS-100/He Biolistic Particle Delivery System. Labeled retina was fixed with 4% paraformaldehyde in 0.1 M phosphate buffer (pH 7.4) for 60 min, washed three times with 0.1 M PB, and then mounted on a slide with 50% glycerol. We collected the images of labeled ganglion cell using a Leica DMRA microscope equipped with a Spot cooled CCD camera. Results: A large number of mouse retinal ganglion cells were labeled (P0: 135, P8: 361 and P13: 477). The mouse retina ganglion cells were classified by soma size, dendritic field size, level of stratification and branching pattern. The P0 mouse RGCs stratify diffusedly and differentiate poorly, and they were classified into two types according to the complexity of the dendritic field. By P13, almost every cell can be classified into one of the 14 adult subtypes. And at P8, despite some of poorly differentiated cells, almost every adult subtype was present. Conclusions: Neither the bipolar cell inputs nor the well-focused light stimulus are required for the morphological maturation of the mouse retinal ganglion cells during early postnatal development. The role of amacrine cells in the development of the mouse retina ganglion cell morphology is still unclear. This study obtained a systematic and detailed description of the morphological development of the retinal ganglion cells in a popular mammalian model for transgenic manipulation, and provided a foundation for further investigations in morphological and functional changes of retina ganglion cells in animals with genetic manipulation.
Keywords: ganglion cells • retinal development