Peculiarities of the manifestation of the visual state of Clarias gariepinus in the early periods of ontogenesis

Abstract

Clary catfish are distinguished by their unique biology and specific development, as they are able to move on land and breathe atmospheric air for a long time. Living in water and on land can affect the microstructure of the eye structure, since it is known that the organs of vision of animals in different habitats have their own specifics.

Due to the poorly studied organs of vision in Clarias gariepinus, we set out to use different dyes to study the microstructure of the eye in the early periods of ontogenesis and determine the most effective methods of histological staining.

The object of the study was the fry of the marbled catfish at the age of 14 days. The material for making histological sections was the organs of vision of Clarias gariepinus. Staining was carried out in two ways: with Gill hematoxylin and eosin alcohol solution, and we also tried out Mallory's staining.

The results of our research have confirmed the data of other authors that the process of formation of all layers of the organ of vision occurs at the stage of pre-larvae. Already on the second day, active eye mobility and the reaction of the visual apparatus to light were recorded in experimental fish. The cornea of the eyes is flat, which is typical for aquaculture facilities. The microstructure of the eye is represented by clearly distinguishable layers on the 14th day after hatching. On the longitudinal section of the micropreparation, when stained with hematoxylin Gill and 1% alcohol solution of eosin, the actual vascular membrane of the retina of the eye, consisting of loose fibrous connective tissue, is visible. The outer layer of the retina is represented by rods and cones, which contain bipolar neurons, as well as a photosensitive pigment, which is clearly distinguished when stained with hematoxylin by Mallory.