Histochemical demonstrations of the lens of the sailfin molly (<i>Poecilia latipinna</i>) with retinal adaptation

The study revealed that histochemical examination of the lens and retina in the fish Poecilia latipinna reflects adaptation and acclimation to dark and light conditions. The tissue sections of the lens and retina were stained with different stains and examined by a light microscope. The lens was found to be spherical in shape, transparent, hard, and avascular. The lens was surrounded by a cellular homogeneous capsule and followed by cuboidal epithelial cell layer, which was situated beneath the capsule. The epithelial cells elongated into lens fibers that were arranged in concentric rings, and the lens fiber membranes took a serrated shape that overlapped with each other. The study showed that the retina was composed of two layers: the inner, known as the neural retina, and the outer, known as the pigmented epithelial layer. The neural retina also consists of the visual cell layer, the external limiting membrane, the outer nuclear layer, the outer plexiform layer, the inner nuclear layer, the inner plexiform layer, the ganglion cell layer, the nerve fiber layer, and the internal limiting membrane. The visual cell layer was found to consist of rods and rich in cones, which included single and double cones. The internal limiting membrane was distinguished by the presence of vitreal blood vessels that extended within this membrane. Thus, visual acuity plays a main role in the life of the sailfin mollyfish.