A model describing the cellular and molecular events at the asymmetric fusogenic synapse. (1) An FCM is attracted by a founder cell/myotube. (2) The FCM and founder cell/myotube adhere via the interaction of cell adhesion molecules (only Duf and Sns are shown) at the site of fusion. In the FCM, Sns recruits both the Scar and WASP complexes to induce the formation of a dense F-actin focus. In the founder cell, Duf recruits the Scar complex to induce the formation of a thin F-actin sheath. (3) In the FCM, the cell adhesion molecule and the F-actin focus constitute a podosome-like structure (PLS) and, through the action of the WASP–Sltr complex, the PLS protrudes multiple invasive fingers to palpitate the founder cell membrane. (4) We speculate that a nascent fusion pore forms at the tip of a podosome finger, where the two adherent membranes are brought into close proximity through the interactions between the podosome finger in the FCM and the thin sheath of actin in the founder cell. (5) The nascent fusion pore expands to a single-channel macro fusion pore after F-actin depolymerization. (6) The FCM completely incorporates into the founder cell/myotube, contributing one additional nucleus.