A preovulatory temperature gradient between the isthmus and ampulla of pig oviducts during the phase of sperm storage

Abstract

Summary. Fine thermistor probes positioned in each end of the same oviduct and connected to the same scale were used to measure temperature gradients in the lumen before and after spontaneous ovulation in normally-cyclic gilts. Readings were taken after full surgical closure of a mid-ventral incision and a subsequent period of stabilization, but whilst animals remained under general anaesthesia.A small but consistent difference in temperature was recorded between the proximal ampulla and distal isthmus of the same oviduct in each of 20 preovulatory gilts. In 10 of these animals that had not mated, the isthmus was a mean of 0\m=.\43\s=deg\Ccooler than the ampulla (range 0\ m=. \ 2\ p=n-\ 0\ m=. \ 7\ s=deg\ C whereas in 10 mated animals the isthmus was 0\m=.\69\s=deg\Ccooler (range 0\ m=. \ 2\ p=n-\ 1\ m=. \ 6\ s=deg\ C 3 animals in the latter group had within-oviduct differences of \ m=ge\ 1\s=deg\C. By contrast, in 12 animals that had recently ovulated, the isthmus was a mean of only 0\ m=. \ 1\ s=deg\ Ccooler than the ampulla; there was no measurable temperature gradient in 3 of the animals, whilst the isthmus was 0\ m=. \ 1\ s=deg\ C warmer in 2 animals. The preovulatory temperature differences are thought primarily to reflect the extent and activity of the vascular and lymphatic beds in the oviduct tissues and, together with specific chemical microenvironments, may facilitate the relatively prolonged period of sperm storage in the distal portion of the isthmus.

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

“…Fallopian tube physiology 287 10 mated animals, the caudal isthmus was a mean of 0.7 °C cooler than the proximal ampulla, a gradient that was not demonstrable after ovulation [15]. Accordingly, the relatively cooler pre-ovulatory temperature of the caudal isthmus was suggested to contribute to reduced sperm motility and the phase of storage.…”

Considerations of viscosity in the preliminaries to mammalian fertilisation

“…In particular, there may be temperature gradients within the oviduct of oestrous animals [11,[48][49][50]. Values in the literature suggest that these can be of the order of 1°-2°C or more between the caudal portion of the isthmus and the cranial portion of the ampulla in the hours before ovulation.…”

“…Values in the literature suggest that these can be of the order of 1°-2°C or more between the caudal portion of the isthmus and the cranial portion of the ampulla in the hours before ovulation. This was proposed to contribute towards reduced sperm motility and a sperm storage function of the caudal isthmus [49]. The magnitude of the temperature gradient may change according to the stage of the cycle and especially according to the time of ovulation [49].…”

“…This was proposed to contribute towards reduced sperm motility and a sperm storage function of the caudal isthmus [49]. The magnitude of the temperature gradient may change according to the stage of the cycle and especially according to the time of ovulation [49]. Therefore, a possible influence of temperature on the viscosity and viscoelasticity of female tract fluids and on the zona pellucida needs to be considered, and this might be most significant at the time when viable spermatozoa would be expected in the oviduct.…”

Whither human IVF? Fertilisable oocytes selected on the basis of follicular temperature

“…We have had a specific interest in temperature physiology in mammalian oviducts and ovaries for some three decades [4][5][6]. Perhaps, the most significant finding to come from such studies is that both male and female gametes are subjected to temperatures cooler than those in neighbouring tissues in the hours shortly before the onset of fertilisation [7][8][9].…”