Schistosome parasite eggs. Light micrograph of eggs (centre left) of the parasite Schistosoma mansoni in the mucous membrane (mucosa) of the human intestine. This parasitic trematode worm causes schistosomiasis or bilharzia in humans. Adult worms live in pairs in the bloodstream surrounding the digestive system. Eggs or schistosomes cross from the blood vessels into the digestive tract, from where they are excreted with the faeces. Occasionally eggs become trapped, causing granulomas or scar tissue to form. A female worm can produce 300 eggs per day. Magnification: x30 at 35mm size.