When the hagfish contracts these gland muscles, the thread cells and mucous cells are pushed out as a concentrated mixture through the gland duct. Travelling through the duct and actively mixing with seawater outside the gland opening cause the cells to burst and release their packaged contents into the water. The bundled protein threads unravel and the mucins from ruptured vesicles attach to them, and this network rapidly expands into a large, dilute mass of slime that temporarily holds water like a fine sieve.