Thread Cells from the Slime Glands of Hagfish (Myxinidae)

Scanning electron microscopy and light microscopy demonstrate that the mature thread cells in Eptatretus deani and Myxine glutinosa consist of a single, coiled thread up to 10 cm long. Mature thread cells apparently loose the cell membrane within the slime gland before expulsion. Thus the old idea that rupture of the cell membrane causes the uncoiling in sea water is no longer tenable. If the thread cells are transferred without additional fluid to a microscope slide, no uncoiling occurs until sea water or distilled water is added when the process occurs rapidly; however, in double strength sea water uncoiling is slowed down. In tetrahydrofuran or glycerin there is no uncoiling in 100 % or 50 % solutions; however in 5 % solutions uncoiling occurs slowly. Thus the availability of adequate amounts of water seems to be necessary for uncoiling. Presumably, water acts directly on the thread, causing the organelle to straighten and thus uncoil. The defensive value of the slime production is discussed.