Sensory Organs

Abstract

AbstractIn addition to the visual (eye), taste (taste buds), hearing (inner ear) and smell (olfactory sac) organs, zebrafish also have unique skin sensory organs (lateral lines) of fish. The eyeball is spherical and consists of eyeball wall and eyeball content. The wall of eyeball is composed of fibrous membrane, vascular membrane and retina from outside to inside. The fibrous membrane consists of cornea and sclera. The vascular membrane is located inside the fibrous membrane. In front of the crystalline lens, the vascular membrane is called iris, and the rest vascular membrane is choroid. The retina is the innermost layer of the eyeball wall, lining the inner surface of the choroid, and can be divided into 10 layers. From outside to inside, there are pigmented epithelium, photoreceptor (cone cell and rod cell layer), external membrane, outer granular layer, outer plexiform layer, inner granular layer, inner plexiform layer, ganglion cell layer, nerve fiber layer and internal limiting membrane. The crystalline lens is spherical, fixed and suspended behind the iris by suspensory ligaments. It is mainly composed of lens fibers and lens capsule, without blood vessels and nerves. Conjunctiva is a layer of mucous membrane covering the eyelid and in front of the eyeball. It is a transparent film formed by stratified columnar epithelium and a small amount of connective tissue. It is the main auxiliary organ of zebrafish eye. Zebrafish only have inner ear, no middle ear and outer ear. The inner ear is composed of three semicircular canals, ampulla and auditory sac. The olfactory sac of zebrafish is invaginated and connected with the outside world. The mucosa of the olfactory sac is wrinkled and lined with an olfactory sac membrane composed of olfactory epithelium and lamina propria. The olfactory epithelium is composed of olfactory cells, supporting cells and basal cells.