Description of Fallopian tubes
The Fallopian tubes are muscular canals extending from the cornua of the uterus and opening into the peritoneal cavity near the ovaries. It helps to move released or fertilized eggs to the uterus for implantation. Blocked fallopian tubes is one of the causes of infertility in women.
Fallopian tubes are also called oviducts, uterine tubes or salpignx, which are conduits through which spermatozoa pass through to fertilize the ovum at the ampullary portion of the tube.
Each tube measures 10cm in length and 6mm in diameter and is enveloped in the upper poles of the broad ligament.
The tubes have a lumen which communicate with the uterine cavity medially and opens into the peritoneal cavity laterally.
Gross structure of the Fallopian tubes
Each tube is described in 4 parts
- The Interstitial part
- The Isthmus
- The Ampulla
- The Infundibulum
The Interstitial part:This is the narrowest part of the tube measuring 1.23cm in length and lying within the thickness of the uterine wall. It’s lumen measures 1 mm in diameter.
The Isthmus: This is a narrow portion of the tube, extending for about 2.5cm laterally from the uterine walls.
The Ampulla: This is much wider than the Isthmus, extending for about 5 cm from the Isthmus towards the side wall of the pelvis. Fertilization of the ovum takes place in the .
The Infundibulum: This is the last of the tube which measures 2.5m & turns backwards and downwards. It is funnel shaped and composed of numerous finger- like processes/ projections called the fimbriae which surrounds the tubal orifice. One fimbra is attached to the ovary and is known as “the fimbria ovarica” and is the longest of all.
Microscopic structure of Fallopian tubes
Each uterine tube has three layers:
- Endometrial layer
- Muscular layer
- Peritoneal layer
The Endometrial layer: This is an inner lining of mucous membrane thrown into complicated folds known as the plicae. The folds are designed to slow down the passage of the ovum to the uterus . Note that the mucous membranes in the cervix are arranged in tree-like structure known as arbo vitae.
The plicae are more developed in the ampullary part of the ovidicts. Many of the cells of the lining are made of cubical epithelium and are ciliated.
The non-ciliated cells are called goblet cells and they secrete mucus into lumen of the tube shortly before menstruation. Beneath the inner lining is a layer of vascular connective tissue.
The Muscular layer: The muscle coat consist of two layers: (a) an inner circular layer which surrounds the mucous layer and (b) an outer layer of longitudinal smooth muscles.
The peritoneal layer: This is an outer covering of peritoneum which is absent along the inferior surface of the tube between the layers of broad ligament.
Anatomic surroundings
- Medially: The uterus
- Laterally: The Infundibulopelvic ligaments and side walls of the pelvis.
- Anteriorly, superiorly and posteriorly: the peritoneal cavity and the intestine
- Inferiorly: broad ligament and ovaries.
Blood, Nerve & Lymphatic supply to Oviducts
- Blood supply: through the uterine and ovarian arteries.
- Venous Drainage: By the corresponding veins.
- Lymphatic: through the lumbar glands
- Nerve Supply: Mainly from the ovarian plexus.
Functions of Fallopian tubes
- The tube conveys ova from ovaries to the uterine cavity
- The peristaltic movement from the tube aids the passage of spermatozoa into the ampullary portion where fertilization takes place.
- Mucous membrane of the fallopian tube produces fluid secretion containing glycogen for nourishment of the ovum
- It is responsible for the early development i.e. segmentation and early differentiation of the developing zygote.
Disorders of Oviducts
- Salpingitis
- Pelvic Inflammatory Disease.
- Endosalpingiosis.
- Ectopic Pregnancy
- Blocked uterine tubes
- Infertility and Tubal Factor.
- Isolated Tubal Torsion.
- Paratubal Cyst.