Botany: Wheat, triticum, germ. Front view of a germinating grain of wheat (Triticum sp.). The majority of the seed comprises a store of starch surrounded by a seed coat (yellow). This starch provides the embryo plant with the necessary energy for germination. Germination may be triggered by humidity, temperature or other factors.
Medicine: Skin, lateral cut. A section through human skin. The skin layers, from top to bottom, are the stratum corneum (flaky, brown), composed of flattened, dead skin cells that form the surface of the skin. The dead cells from this layer are continuously being shed and replaced by cells from the living epidermal layer below (red) The lowest layer seen here is the dermis (grey-brown, lower centre), a thick layer of fibrous connective tissue that supports and nourishes the epidermis. In the middle, a sweat gland can be seen.
Medicine: Immune system, Macrophage, defense against microfilarie. A Microfilariae (larval worms) of a parasitic nematode roundworm being attacked by cells of the immune system. Numerous nematodes cause disease in humans, living as parasites of the intestines, blood, lymph, subcutaneous & connective tissues.
Fungus: Aspergillus fungus (aspergillus fumigatus). The fungus is made up of fungal threads (hyphae, grey) with conidiophores (fruiting bodies, brown) at the tip. The conidiophores are made up of chains of conidia (spores), which are dispersed on the wind. Inhalation of spores by people with a weakened respiratory system, for example asthmatics or those with cystic fibrosis, leads to an allergic reaction known as aspergillosis. A. fumigatus usually grows on decomposing organic matter.
Zoology: Shark skin (acanthias acanthias). Scales from the skin of a shark. These sharply pointed placoid scales are also known as dermal teeth or denticles. They give the shark's skin the feel of sandpaper. The tip of each scale is made of dentine overlayed with dental enamel. The lower part of each scale, which anchors it into the skin, is made of bone. The scales disrupt turbulence over the skin, considerably reducing the drag on the shark as it swims. This design has been investigated by engineers for use on the surfaces of aircraft and boats.
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