The infundibular portion of the fallopian tube is the funnel-shaped distal end that opens directly into the peritoneal cavity. It is characterized by the presence of fimbriae, which help capture the ovulated oocyte. This direct communication with the peritoneal cavity is clinically significant during surgical procedures such as tubal ligation or ectopic pregnancy management, as it presents a potential site for infection or fluid leakage. Understanding its anatomy ensures precise intervention and prevents injury to surrounding structures.

Reference: Gray's Anatomy, Standring S, 42nd Edition.