Infundibulum

The infundibulum is the funnel-shaped, distal segment of the uterine (fallopian) tube that opens into the peritoneal cavity near the ovary. It is bordered by multiple fimbriae, including the ovarian fimbria, which play an essential role in capturing the oocyte after ovulation. The infundibulum connects laterally to the fimbrial fringe and medially to the ampulla of the tube. It forms a critical anatomical and functional link between the ovary and the rest of the female reproductive tract.

Structure

The infundibulum is a flared, trumpet-shaped portion of the uterine tube. Its walls are thinner than the ampulla and contain mucosal folds that extend into the lumen. The inner surface is highly ciliated to promote oocyte movement. The margin of the infundibulum is fringed with fimbriae that help guide the oocyte into the fallopian tube.

• Length: Approximately 1 cm
• Diameter: Broadest part of the tube after the fimbriae
• Structure: Thin muscular wall, highly folded mucosa, ciliated epithelium

Microscopic Features

• Mucosa: Lined with ciliated columnar epithelium and secretory peg cells
• Muscularis: Thin layers of circular and longitudinal smooth muscle
• Serosa: Outer peritoneal covering derived from mesosalpinx

Location

The infundibulum is the lateral-most segment of the uterine tube, situated between the fimbriae and the ampulla. It lies adjacent to the superior pole of the ovary and opens into the peritoneal cavity via the abdominal ostium of the uterine tube.

Function

• Oocyte Capture: Receives the oocyte released from the ovary during ovulation
• Oocyte Transport: Cilia and smooth muscle contractions guide the oocyte toward the ampulla for possible fertilization
• Peritoneal Communication: Only point of open communication between the female reproductive tract and peritoneal cavity

Blood Supply

• Arterial: Tubal branches of the ovarian artery and uterine artery
• Venous: Tubal veins → ovarian and uterine venous plexuses → internal iliac and renal veins

Lymphatic Drainage

• Para-aortic (lumbar) lymph nodes

Innervation

• Autonomic fibers from the ovarian and uterine plexuses
• Sympathetic: T10–L2 spinal segments

Embryological Development

• Derived from the cranial, unfused portion of the paramesonephric (Müllerian) duct
• Develops as part of the lateral expansion of the uterine tube system

Clinical Significance

• Ectopic Pregnancy: The infundibulum may be a site of implantation if tubal transport is disrupted
• Salpingitis: Infections can ascend through the infundibulum into the peritoneal cavity, causing pelvic inflammatory disease
• Fimbrial Blockage: Obstruction of the infundibulum or fimbriae can impair oocyte pickup and lead to infertility
• Tubal Ligation: Surgical sterilization often targets the ampullary-infundibular junction