The Nikon MicroscopyU confocal microscopy image gallery was created with a PCM-2000 confocal scanning system interfaced to a Nikon Eclipse E600 upright microscope. Images were recorded in successive z-axis serial sections with C-Imaging Systems software with excitation illumination provided by an argon-ion and/or a helium-neon laser.

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View a lower magnification confocal sequence of a frog eye.

After outliving dinosaurs, frogs have changed very little from their ancestors who roamed the earth 150 million years ago. These slippery creatures can be found atop freshwater lily pads, among the canopies of tropical rainforests, burrowed deep into the sands of the Australian desert, or even hibernating in Arctic soil.

Thin slippery amphibian skin is among the most unique in the animal kingdom. Most frogs rarely need to drink because they have permeable skin that can directly absorb the water they need from the environment. Some frogs have stomach skin that porous enough to enable the animal to soak in moisture from the ground. The smooth delicate body covering is also permeable to air so that oxygen and gases easily pass through. Although frogs have lungs, their ability to absorb air from moist surroundings is especially useful when burrowing deep into submerged mud. Frogs are covered in mucus secreting glands that help to keep their slippery skin moist and pliable. Many frogs also secret a waxy substance that helps to control water evaporation from their bodies during hot summer days.

Although tireless hunters of insects, frogs themselves are very edible and must evade a spectrum of predators. In order to protect themselves, many of these small creatures secrete sticky, noxious tasting or smelly mucus. The skins of some frogs even produce poisonous toxins. Used to coat the tips of blowpipe darts and arrowheads, these lethal biochemicals are prized by Central and South American Indians. Scientists are also investigating toxins that are produced by the poison-arrow frog and hope to discover new treatments that can cure human illnesses.

The secret of survival for these small creatures may be due in part to their specialized permeable skin. However, researchers are becoming increasingly concerned that many environmental toxins such as pesticides and chemicals also seep into the skin of embryos, tadpoles, and adult frogs causing mutations and deformities.