A small, elongated secretory organelle that forms part of the apical complex, located along the main axis of an apicomplexan parasite cell within the extreme apical region and at the periphery under the inner membrane complex. Of the specialized secretory compartments identified in apicomplexans, micronemes discharge their contents first, during initial contact of the parasite's apical pole with the host cell surface. Micronemal proteins function during parasite attachment and penetration into the target cell.

Secretory organelle in the apical complex of parasitic phylum APICOMPLEXA (e.g., TOXOPLASMA GONDII). Microneme plays a role in junction formation between the parasite and the host cell by releasing micronemal proteins, which bind to receptors on the host cell surface enabling parasite attachment.