Where is the tapetum located

Vertebrates are a subgroup of chordates, which all have a flexible, rod-shaped structure that supports the body called a notochord. Non-vertebrate chordates include tunicates, hagfish, and lancelets. In vertebrates the notochord ultimately becomes part of the spine, usually encased in bony joints.

All chordates also have a dorsal hollow nerve cord that forms the nervous system and pharyngeal slits that open outside the body during development and persist to form gills in aquatic animals.

It normally functions to provide the light-sensitive retinal cells with a second opportunity for photon-photoreceptor stimulation, thereby enhancing visual sensitivity at low light levels…. In vertebrates, the tapetum lucidum exhibits diverse structure, organization and composition. Therefore, the retinal tapetum teleosts, crocodilians, marsupials, fruit bat , the choroidal guanine tapetum elasmobranchs , the choroidal tapetum cellulosum carnivores, rodents, cetacea , and the choroidal tapetum fibrosum cow, sheep, goat, horse are described….

These variations regarding both its location and structure, as well as the choice of reflective material, may represent selective visual adaptations associated with their feeding behavior, in response to the use of specific wavelengths and amount of reflectance required.

Randomly arranged filaments scatter all wavelengths of light, and their optimized spacing maximizes the effect. Light intensity concentrates hormones that alter the water levels in cells causing plants to bend toward the light source.

The retinal epithelium over the tapetum is nonpigmented while in non-tapetal locations it is normally pigmented. Abstract The tapetum lucidum of the paca or spotted cavy Cuniculus paca has been studied by light and electron microscopy. Publication types Research Support, Non-U. In light-adaptation the small melanosomes of the melanocytes are widely dispersed and fill the portion of the cell intervening between the tapetal cells and the incoming light.

This effectively occludes the tapetum as light is unable to reach the reflective material. In dark-adaptation the melanosomes withdraw from this location, exposing the tapetum to light and allowing it to act as a reflective layer.

The retinal epithelium overlying the tapetal area is totally unpigmented so as not to interfere with the passage of light.