Outstanding questions concerning sperm-epithelial binding in the mammalian oviduct.

Preovulatory binding of viable spermatozoa in the oviduct isthmus is widely accepted as a preliminary to fertilization, but details of physiological events associated with epithelial binding and release from binding are themselves little understood. Important questions include the potential number, distribution and stability of such sites in the caudal isthmus, whether multiple molecular forms of binding exist within a single-mated individual, and whether some sites are more favourable than others for the maintenance of preovulatory sperm viability. Also to be resolved is whether spermatozoa interact with the first available binding sites in the isthmus, whether spermatozoa from second or subsequent matings bind closer to the site of fertilization, and whether the first spermatozoa entering the oviduct are those that will be released first with impending ovulation.

Presence and significance of temperature gradients among different ovarian tissues.

After recalling male gonadal physiology in respect of tissue temperatures within the scrotal sac, and raising questions concerning abdominal testes, attention turned to mature Graafian follicles and ovarian stroma. Temperature gradients between such tissues were summarized for human, rabbit, pig, and cow, and generally fell in the range of 1.3-1.

The Fallopian tubes in domestic mammals: how vital is their physiological activity?

Set in an historical perspective, this essay examines diverse physiological aspects of Fallopian tube function in domestic animals and man. Microsurgical experiments are described that established the role of the isthmus in imposing a sperm gradient up to the site of fertilisation. Resection of the isthmus followed by reanastomosis of the remaining portions of the tube generated a high incidence of polyspermy in mated animals.