Fig. 1

Melanoma FEMX-I cells harbor bipolar or triangular morphotypes and contain lipid droplets and mitochondria at their extremities. A-F FEMX-I cells growing on poly-L-lysine-coated coverslips (A-E) or on plastic Petri dishes (F) were processed for scanning (A-E) and transmission (F) electron microscopy. Two main morphotypes are observed; cells with a bipolar and tripolar shape (see illustration in A). Their extremities are either short and flattened with filopodia adhering to the support (A-D, dashed line) or long and narrow (A, E, straight dotted line and red arc). Various small, rounded particles are observable particularly at the extremities of the cells when applying a higher acceleration voltage (15 kV instead 5 kV) during SEM analysis (C-E, yellow arrowhead). These homogeneous intracellular particles appear as opaque spheres by TEM, which is the typical appearance of lipid droplets (LD, F, see enlargement of images f’ and f’’). Mitochondria (MT) are present in the vicinity of lipid droplets (see also Additional file 1: Fig. S2). Scale bars are indicated