Coloured scanning electron micrograph (SEM) of a sperm (blue) attempting to penetrate a human egg (orange). Actually, it takes a great number to weaken the outside of the egg enough for one to fertilize it.
☤ MD ☞ ☆☆☆ Colored scanning electron micrograph (SEM) of squamous cell carcinoma (cancer) cells from a human mouth. The many blebs (lumps) and microvilli (small projections) on the cells' surfaces are typical of cancer cells.
Nerve fibres. Coloured scanning electron micrograph (SEM) of fractured myelinated nerve fibres. The myelin sheath is green, the axoplasm is pink and the endoneurium (connective tissue) is blue. Magnification: x800 when printed at 10 centimetres wide.
Bdelloidea are microscopic aquatic animals that are related to roundworms, found in freshwater and moist soil. Interestingly, a male has never been observed within the species; females reproduce exclusively by parthenogenesis (without fertilization).