right|thumb|350px|Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus. 2- Pilus attaches to recipient cell, brings the two cells together. 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell. 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili; both cells are now viable donors. A pilus (Latin for 'hair'; : pili) is a hair-like cell-surface appendage found on many bacteria and archaea. The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All conjugative pili are primarily composed of pilin – fibrous proteins, which are oligomeric.
right|thumb|350px|schematic drawing of bacterial conjugation 1- donor cell produces pilus 2- pilus attaches to recipient cell brings the two cells together 3- the mobile plasmid is nicked and a single strand of dna is then transferred to the recipient cell 4- both cells recircularize their plasmids synthesize second strands and reproduce pili; both cells are now viable donors a pilus (latin for 'hair';  pili) is a hair-like cell-surface appendage found on many bacteria and archaea the terms pilus and fimbria (latin for 'fringe'; plural fimbriae) can be used interchangeably although some researchers reserve the term pilus for the appendage required for bacterial conjugation all conjugative pili are primarily composed of pilin – fibrous proteins which are oligomeric