Demodex folliculorum - Skin : 無料・フリー素材/写真
Demodex folliculorum - Skin / Y Rosen, MD & P Meseguer, MD
| ライセンス | クリエイティブ・コモンズ 表示-継承 2.1 |
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| 説明 | In the photograph we see three specimens of Demodex folliculorum in the infundibulum of a hair follicle. Demodex folliculorum is a microscopic mite that can survive only on the skin of humans. Most people (90%) have D. folliculorum on their skin. Demodex folliculorum measures 0.3 to 0.4 mm long. Adults have four pairs of legs; larvae and nymphs have only three pairs. The entire life cycle of Demodex takes 14–16 days. Adult mites copulate at the top of the hair follicle, near the skin surface. Eggs are deposited in the sebaceous gland inside the hair follicle. The heart-shaped egg is 0.1 mm long, and hatches into a six-legged larva. In seven days the larva develops into a mature adult, with two intervening nymph stages. Usually, the mites do not cause any harm, so are considered an example of commensalism rather than parasitism; but they can cause disease, known as demodicosis when they grow excessively. In the present case, the mite has been exposed to the host's immune system when the follicle that contained it ruptured due to a wound. You can see scarring fibrosis on top and an inflammatory reaction with macrophage lymphocytes and giant cells around the arthropod.These mites have nocturnal habits, moving up to 16 mm/h, making very intimate contact necessary for transmission between people. It is believed that the main transmission is from mother to child during breastfeeding.The term Demodex is derived from the Greek words, "demo" (lard) and "dex" (boring worm) to describe the preferred shape and location of this organism. #demodex Images contributed by Dr. Meredith Herman - @MeredithKHermanOther photos of Demodex folliculo#rum can be seen in this Atlas. |
| 撮影日 | 2025-03-09 13:43:50 |
| 撮影者 | Y Rosen, MD & P Meseguer, MD |
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