Compound eye

The compound eyes of insects are formed of a hexagonal array of small units, or ommatidia (in the case of the fruit fly, approximately 800 small eyes ). Each is composed of eight photoreceptor cells... 

Fig. 13.3.6 Compound eye of insect Lasius niger Untie (a) arrangement of close packed ommatidia (b) head composed of compound eye antennas and mouth (c) ordered arrange om-matidia on the convex spherical surface (compound eye). (From O. Hojiro, with permission.)...

Figure 13.3.6 shows a compound eye of the insect Lasius niger linne. The head composed of compound eye, antenna, and mouth is observed in Fig. 13.3.6c. Many ommatidia are ordered arrange on the convex spherical surface, as observed in Fig. 13.3.6b, and also are close-packed completely, as can be seen in Fig. 13.3.6a. Natural pollen grain and insect compound eye are the final approaching standard models for study of the preparation of composite and encapsulated powders.

In higher life forms various types of eye have evolved in the course of time, the simplest one being that of insects these are arrays of elementary eyes (forming the compound eye) each of which respond to light of a particular direction. Insects therefore do not perceive shapes in the human sense, but rather distributions of light intensity in various directions (Figure 5.10). 

Figure 5.10 Three types of eye in evolution (from left to right) the compound eye of insects, the pinhole eye and the eye of higher animals. The photosensitive surface is shown as a thick black line c is the cornea, l the lens and r the retina...

Lenses were known in ancient times, and by the fifteenth century their use in spectacles was common. It was not until the seventeenth century, however, that a convex and a concave lens were put together in a tube to form the first crude microscope. Galileo used one of the first instruments, and he was amazed to discover the compound eyes of insects. Stelluti... 

Insects are typified by three main body segments, which are themselves further segmented, antennae, mandibles, three pairs of legs, two pairs of wings, and compound eyes. There is incredible diversity in this huge group and body types and sizes vary greatly. 

In the great class of the Articulata, we may start from an optic nerve simply coated with pigment, the latter sometimes forming a sort ofpupil, but destitute of a lens or other optical contrivance. With insects it is known that the numerous facets on the cornea of their great compound eye form true lenses, and that the cones include curiously modified nervous filaments. But these organs in the Articulata are so much diversified that Muller formerly made three main classes with seven subdivisions, besides a fourth main class of aggregated simple eyes. 

Fig. 5.12. Adult green lacewing a beautiful insect with lacy wings and compound eyes.

The head contains antennae, eyes, and monthparts. The antennae vary in size and shape and can be a help in identifying some pest insects. Insects have compound eyes, made np of many individnal eyes. These compound eyes enable insects to discern motion, bnt probably not clear images. 

Compound Eye irritation Skin irritation Oral LDgo (9 kg ... 

FDA Cosmetics-use of mercury compounds eye area cosmetics (mercury calculated as the metal) Yes < 65 ppm 21 CFR 700.13 FDA 1974... 

K.C. Smith, E.R. Macagno (1990). UV photoreceptors in the compound eye of Daphnia magna (Crustacea Branchiopoda). A fourth spectral class in single omatidia. J. Comp. Physiol A, 166, 597-606. 

Araujo H, Machado LCH, Mizutani CM, Silva MJF, Octacilio-Silva S, Ramos RGP (2003) Requirement of the roughest gene for differentiation and time of death of interommatidial cells during pupal stages of Drosophila compound eye development. Mech Dev 120 537-547... 

The compound eye of the fly is composed of some 800 individual eyes called ommatidia (Figure 14-17a). Each omma-tidium consists of 22 cells, eight of which are photosensitive neurons called retinula, or R cells, designated R1-R8 (Figure... 

A FIGURE 14-17 The compound eye of Drosophila melanogaster. (a) Scanning electron micrograph showing individual ommatidia that compose the fruit fly eye. 

Figure E49-5. Rice and granary weevils. (A) Head (dorsal view, drawing). (B) Head (ventral view drawing). (C) Head (lateral view drawing). (D) Head (lateral view, actual). (E) Head and antennae (ventral view). (F) Compound eye. (G) Snout with mandibles at the tip.

Figure 2. Interference contrast micrograph of a frontal section of the compound eye that shows the retina and lamina compartments separated by a basement membrane (BM). Lateral facet lenses are present on the outer edge of the section. Each lens in the eye images light onto a single ommatidium. Peripheral photoreceptors in each diamond-shaped ommatidium project axons across the basement membrane with 1 1 retinotopy onto the lamina cartridges.

Figure 5. Light micrograph of a few facets of a fly s compound eye. Dark spots that represent the rhabdomeres of the photoreceptors have been superimposed onto each corneal lens to demonstrate the principle of neuro-superposition. The central corneal facet has been removed from the photograph to depict the underlying lamina cartridge. Anatomically, six peripheral photoreceptor axon terminals (R1-R6) synapse with two second-order cells (LI and L2) in the underlying neuropil that is called the lamina. Each of these six photoreceptors is illuminated by a different lens, but optically they share the same visual axis that is, they look at the same point in space. This lamina subunit is known as neuroommatidium. Axons of the central receptor cells (R7 and R8) from the overlying ommatidium pass close to this cartridge, but simply bypass the lamina and do not contribute synapses at this neural level.

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