Comparison of effects of different fixation methods on the posterior pole of guinea pig eyeballs

AIM: To avoid the problem of retinal dissection in guinea pig large eyeball tissue sections, different methods were used to optimize the fixation effect of the posterior pole of the eyeball.METHODS: A total of 75 normal guinea pigs(2 weeks old)were randomly divided into 5 large groups. Group A(1-3 small groups), the entire eyeball was fixed with FAS, Davidson fixative 1(D1), and Davidson fixative 2(D2)for 24 h; group B(4-6 small groups), the entire eyeball was fixed with FAS, D1, and D2 for 1 h, then cut the cornea and fix it in their respective fixatives for 2 h; group C(7-9 small groups), the eyeball was fixed in FAS, D1, and D2 for 1 h, divided into left and right halves along the direction of the optic nerve, and then placed them in their respective fixation solutions for 2 h; group D(10-12 small groups), after fixation for 3 h in FAS, D1, and D2, the eyeball was divided into left and right halves along the optic nerve direction; group E(13-15 small groups), the cornea was cut after fixation for 3 h in FAS, D1, and D2. Hematoxylin-eosin(HE)staining was used to compare the fixation effect on posterior eyeball in each group.RESULTS: After fixation, the surface of the eyeballs in groups, 1-6 and 11-15 was smooth and round, with a transparent and bright color. In groups 7-10, the eyeballs were sunken, wrinkled, and deformed. The HE staining showed that the eyeball morphology of groups 1, 5, 6, 14, and 15 was significantly better than the other groups, with a regular internal tissue structure. The eyeballs of the other groups were sunken and wrinkled, and the internal tissue was curled and tangled, with severe retinal detachment. In groups 1, 5, 6, 14, and 15, the retina, choroid, and sclera tissues of group 14 were closely connected, without obvious retinal detachment, rupture, or curling. The tissue structure was clear and visible, and the cells were arranged neatly.CONCLUSION: The fixation effect of cutting the cornea after fixing guinea pig eyeball with D1 fixative for 3 h is the most ideal, and this operation method is simple and suitable for studying the related structures of the posterior pole of the eye.