Each hexagonal-shaped philospheric unit of the grasshopper’s stem is called an ommatidium. Each panicle contains 1200-1800 ommatidia. The structure of an ommatidium is described below.
1. Cornea: The colorless, transparent, convex and hexagonal covering on the outside of the ommatidium is called the cornea. It works like a lens.
2. Corneagen cells: A pair of corneal cells are present under the cornea. It creates the cornea. Dr. Siddiq Publications
3. Crystalline Corneal Cells: Below the corneal cells are four crystalline corneal cells. It forms crystalline cones.
4. Crystalline angle: Crystalline angle is a spheroid organ covered by crystalline angle cells. Light enters the ommatidium through this.
5. Irish Pigment Coat: The colored coating around the crystalline corner cells is called Irish pigment coat. It expands in intense light and covers the corner cells and shrinks in soft light and leaves the corner cells partially exposed.
6. Retinular cells: Below the angle cells there are 7 long retinular cells. It is decorated in circular form. One end of them is connected to the angle cell and the other end to the nerve fiber. It is a light sensor. Rhabdomes are formed from their secretion.
7. Rhabdome: The spindle-shaped cells in the center of the retinular cells are called rhabdome. Light is received through this. Dr. Siddiq Publications
8. Retinal sheath: The black membrane surrounding the retinal cells is called retinal sheath. It separates two adjacent ommatidia.
9. Basal membrane: The thin membrane on which the ommatidium rests is called the basal membrane. It contains the ommatidium.