Investigations Into the Anti-Fertility Effect of Intra-Uterine Devices in the Ewe

Abstract

Ovum fertilization after natural mating was inhibited in both oviducts after the insertion of a plastic spiral into one uterine horn. Spermatozoa were found in oviducts of control ewes between 4 and 24 hr after mating, but were almost totally absent from both oviducts of ewes with a spiral in one horn. Sperm numbers in the uterus were relatively low in`s piral' ewes. Spirals had these effects both 2 to 4 weeks and 8 to 10 months after insertion.Ova were fertilized in`s piral' as well as control ewes after injection of semen into the uterus, but there were fewer accessory spermatozoa in ova from`s piral' ewes. After injection of semen into one uterine horn, spermatozoa were found throughout reproductive tracts of`s piral' and control ewes, but most spermatozoa in horns containing a spiral were broken into heads and tails. Similarly, when semen was injected into ligated uterine compartments, most spermatozoa recovered 5 hr later from spiral compartments were tailless; most spermatozoa recovered from non-spiral compartments of the same ewes were intact. Spirals inhibited sperm transport following natural mating, and they also promoted spermicidal conditions in the uterine lumen.

Uterine Contractions in the Ewe During Progestagen-Regulated Oestrus

“…The effect of progestagen on the direction of uterine contractions in the ewe is somewhat similar to the effect of placing a plastic spiral in the uterine lumen, which 'reverses' the direction of uterine contractions and inhibits sperm transport (Hawk, 1967;Brinsfield & Hawk, 1969). Whether the effects of a plastic spiral and progestagen treatment have similar physiological bases is not clear, but it appears that uterine motility patterns in oestrous ewes can be disrupted by seemingly diverse treatments.…”

Influence of Ovarian Hormones on Sperm 'Breakage' and Disappearance in Sheep Uteri

“…Endogenous or exogenous oestrogen intensified sperm breakage in the uterine lumen of rabbits, as well as in the ewes of the present and previous study (Conley & Hawk, 1970a, b). The presence of a plastic spiral in the uterine lumen of sheep or rabbits greatly increased sperm breakage in the spiral-bearing uterine horn (Hawk, 1967; Conley & Hawk, 1969& Hawk, , 1970a. Progesterone decreased sperm breakage in the uterus of rabbits (Conley & Hawk, 1970b) (Hawk & Conley, 1971).…”

Rapid Disruption of Sperm Transport Mechanisms by Intra-Uterine Devices in the Ewe

“…Three experiments were designed to determine whether an IUD inserted during oestrus could alter the normal operation of sperm transport mechanisms within a few hours. An additional experiment was designed to determine whether sperm transport would return to normal within a few hr after an IUD was removed.Each IUD was a plastic spiral made from polyethylene rods, as described previously (Hawk, 1967 …”

“…tion, apparently by causing a reversal in the direction of uterine contractions (Hawk, 1965(Hawk, , 1967Brinsfield & Hawk, 1969;Mann, 1969). These effects were found weeks or months after the devices had been inserted.…”

“…Each IUD was a plastic spiral made from polyethylene rods, as described previously (Hawk, 1967 (Brinsfield & Hawk, 1969;Mann, 1969). In the study by Mann (1969), catheters were inserted into the sheep uterus at two points and intraluminal pressures were In the fourth experiment, an IUD was inserted into each of ten ewes, then removed about 1 month later.…”