Figure 3.

Transmission electron micrographs (TEM) of gland thread cell (GTC) development. Development series of hagfish GTCs reveals dramatic changes in nuclear size and shape as the cell matures. Immature GTCs, which lack a slime thread, can be identified by their prominent nuclei and nucleoli, while most of the space within a fully mature GTC is occupied by the thread skein. As the GTC develops, the nucleus becomes more spindle-like, eventually receding to the basal end of the cell in mature cells. Scale bars are 5 μm [24].