Studies on sequential post-mortem changes of isolated chicken eye

Abstract

The present investigation was undertaken to study the sequential postmortem changes of different components of chicken eye and to choose an ideal fixative. Six eyes each were fixed at zero hour, half hour, one hour, one and a half hours, two hours, four hours and twelve hours in ten per cent neutral buffered formalin and gluteraldehyde fixative. Eyes were fixed for a minimum of three weeks. A clean cut was made near to the midline of the fixed eye slightly to one side of it, so that the origin of the optic nerve and pupil were included in the sections. The eye consisted of three tunics; tunica fibrosa consisting of cornea and sclera, tunica vasculosa with choroid, ciliary body and iris and tunica interna consisted of retina. The postmortem changes were mostly appreciated in the cornea, which included condensation of the nucleus of the epithelium of cornea, interepithelial detachment and exfoliation of epithelium. The cytoplasm revealed vacuolar and degenerative changes and there was separation of collagen fibres of corneal stroma. The corneal endothelium showed swelling, lysis and detachment. The presence of lysed erythrocytes was prominent after two hours in the choroid. As the time interval advanced, there were varying degrees of dispersion of melanin pigment. The swelling of the cytoplasm of the ciliary body was more evident in the non- pigmented epithelial layer. The epithelium of the iris showed detachment and fragmentation. Retinal detachment was noticed from zero hour of fixation in GF fixative and ten per cent NBF fixative. The changes were prominent in the ganglion cells which showed condensation of the nuclei along with vacuolar and lytic changes of the cytoplasm. Postmortem changes of pecten were appreciated by the lysed erythrocytes in the capillaries along with the vacuolar degeneration and lytic changes affecting melanocytes and hyalocytes. PAS positive areas were detected in the Descemet’s membrane and Bowman’s membrane of cornea, lens capsule, pecten and layer of rods and cones of retina. Masson’s trichrome staining proved to be useful to appreciate the changes in the collagen fibres, muscles and epithelium. The histometry of the eyeball showed a significant decrease in thickness of cornea at 120 minutes when compared with zero hour in neutral buffered formalin fixative. From the study it can be concluded that GF fixative is a better fixative for eye than 10 per cent NBF fixative.