The three-dimensional architecture of the myosalpinx in mammals: an anatomical model for a functional hypothesis

Direct visualization of the three-dimensional architecture of the tubal musculature (myosalpinx) was made possible by a technique involving chemical digestion of interstitial connective tissue, followed by ultrasonic microdissection and final observations under the scanning electron microscope. The isthmic myosalpinx in the guinea pig, rabbit and in humans consists of muscular bundles that tend to lie longitudinally, circularly or oblique. The muscular bundles along the tubal wall change direction, branch and intermingle with one another, giving rise to an irregular network in which distinct layers are not readily distinguishable. In the ampulla, the muscle bundles form a very irregular three-dimensional network of fibres that follow different orientations. The authors suggest a primary role for such a structure in the random pendular transport of the gametes as well as in the denudation of the egg by deformation of the myotubal wall.