Each normally implanted embryo is preceded by the successful transfer of spermatozoa and ova to the ampulla of the Fallopian tube, fertilisation, and subsequent delivery of fertilised ova to the uterus after a suitable period of time. Any malfunction in the mechanisms controlling these processes can seriously interfere with the ability of an individual, or species, to reproduce. It is therefore necessary to gain a closer understanding of the physiological mechanisms controlling these events. The review presented in this chapter outlines present knowledge on the mechanics, and time relationships, of normal entry and passage of gametes through the Fallopian tube. B. ANATOMY OF THE FALLOPAIN TUBE 1. Morphology The Fallopian tubes are bilaterally placed, each being suspended by a mesenteric peritoneal fold, the mesosalpinx. The following regions of each Fallopian tube are easily recognised (Piliero, Jacobs & Wischnitzer, 1965): 1. The funnel shaped infundibulum containing a fimbriated opening, the abdominal ostium, projecting towards and in contiguity with the ovary. 2. An intermediate dilated portion, the ampulla. 3. The isthmus, a constricted and convoluted segment, providing continuity between its uterine orifice, the utero-tubal junction, and the ampulla. The vascular system of the Fallopian tube has not been clearly defined. Arterial blood originates from anastomoses of the uterine and utero-ovarian arteries in the cow (Hansel & Asdell, 1951), ewe (Sisson & Grossman, 1953), and appears to be similar in the sow (Oxenreider, McGlure & Day, 1965). The venous system follows a pattern similar to the arterial while lymph drainage occurs via the lumbar and inguinal nodes (Sisson & Grossman, 1953). Sympathetic innervation links with the ovarian and hypogastric plexus. Recent evidence reported by Brundin (1964a) suggests ampulla innervation is cholinergic, while fluorescent staining techniques (Brundin & Wirsen, 1964b) indicated adrenergic nerve terminals in the isthmus of the rabbit.