Objective   To study the morphological diversity of retinal ganglion cells (RGCs) in the pathological development of retinitis pigmentosa in royal college of surgeon (RC

S) rats.    Methods   The retinal whole mount preparations of RCS-P

+

and RCS-rdy

+

rats in 21

30

60 and 90 d were stained by DiI to study the morphological diversity of retinal ganglion cells.    Results   In the pathological development of the retina of the RCS rats

the amount of first and second level of dendrite branching

the diameter of first level of dendrite branching

and the frequency of dendrite branching of α subgroup of retinal ganglion cells had no significant difference with each other (P0.05). The diameter of dendrite branching at the first level of α subtype of RGCs was markedly increased by 0.44 μm on the 60th day compared with on the 21st day during the degenerative process of RCS-P

+

rats（2.02±0.17 vs 2.66±0.11 μm

P0.01). Moreover

the diameter of of those dendrite branching at the first level was markedly increased by 0.43 μm compared with RCS-rdy

+

rats on the 21st day（2.66±0.11 vs 2.23±0.10 μm

P0.01). The frequency of dendrite branching of α subtype of RGCs was significantly decreased on the 90th day (15.44±1.50) compared with that at the 21st (26.91±3.01

P0.01)and 30th days (27.20±1.99

P0.05) respectively during the degenerative process of RCS-P

+

rats. In contrast

the frequency of dendrite branching of α subtype of RGCs was increased significantly in the 60th day (28.67±2.78) than in the 21st (16.09±1.71) and 30th days(17.75±1.79) (P0.01)

and in the 90th (26.18±2.48) day than in the 21st day (P0.05) during the development of RCS-P

+

rats. In addition

there were also differences in frequency of dendrite branching of α subtype of RGCs between RCS-P

+

  and RCS-rdy

+

rats on the 21st

30th

60th

and 90th days respectively.    Conclusion   In the pathological development of retinitis pigmentosa

frequency of dendrite branching of α subgroup of RGCs is increased significantly in the early stage

while the frequency of dendrite branching is decreased during middle and late stage. Our research suggests that

the process of α subgroup of retinal ganglion cells may have changed in the retinal degeneration of dendrites of the information transmission function.