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H. L. BUTTLE

In the course of studies on the secretion of prolactin by goats in different physiological states, the concentrations of prolactin in the plasma of male goats were measured throughout the year.

Three intact male goats aged 5½ (Miljohn), 2½ (Rupert) and 1½ (Minto) years at the beginning of the sampling period were used. The goats were maintained under the usual husbandry conditions, being turned out to pasture in the summer and kept in individual pens in a separate male goat house in winter; supplementary heating from infra-red lamps was used when necessary. During the breeding season, all three males were used to mate with females in the herd and all three were fertile. Samples of blood were withdrawn from a jugular vein once a week, between 14.30 and 15.30 hours for a period of 15 months. The blood samples were taken by venepuncture into heparinized syringes, centrifuged at 4°C for

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H. L. Buttle

Summary. Pregnancy in goats is maintained after hypophysectomy at about Day 90 of gestation by injection of 20 mg progesterone or 1 mg LH/day, but not by 5 mg prolactin/day.

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H. L. BUTTLE and J. L. HANCOCK

Summary.

Sows were injected with hcg 2 days after removal of the litter and were examined at laparotomy for evidence of ovulation at varying intervals from 36 to 44 hr after injection. Ovulation was found to occur about 40 hr after injection. hcg-treated sows shed more eggs than untreated sows. Most treated sows failed to show heat within 6 days of removal of the litter, in contrast with untreated sows.

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H. R. L. BUTTLE and J. L. HANCOCK

Previous experiments (Hancock, 1963) have shown that sheep embryos can survive to the 25th day of gestation following the transfer to recipient ewes of fertilized eggs which have been stored for up to 48 hr at room temperature. This communication records the birth of live lambs at full term following the transfer of eggs after this treatment. The technique used was that described previously. Briefly, eggs at the four-to twelve-cell stage were stored in heat-treated sheep serum, with added streptomycin, in stoppered tubes in the dark and transferred to recipient ewes after storage for 24 or 48 hr. Transfers were made 72 to 96 hr after mating of recipients. The donor Welsh sheep were mated to a Welsh ram; the twenty recipients were mixed Blackface, Soay, Wiltshire, Lincoln and Merino crosses sixteen of which were mated to a fertile
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J. L. HANCOCK and H. L. BUTTLE

Summary.

Untreated sows and sows injected with human chorionic gonadotrophin (hcg) 2 or 3 days after removal of the litter were inseminated into the oviducts. All of eleven untreated sows yielded blastocysts (5·2 blastocysts/sow) at autopsy 7 to 10 days later. Five of twenty-five hcg-treated sows yielded a total of thirteen blastocysts.

The results are described of experiments designed to examine more closely the effects of hcg treatment.

It is shown that the small number of embryos recoverable after tubal insemination of hcg-treated sows cannot be explained by failure of fertilization.

Surgical recovery of eggs was less successful in hcg-treated sows than in untreated sows.

The sites of recovery of eggs were studied in treated and untreated sows examined at autopsy at varying intervals after ovulation. Eggs were found in the oviducts of hcg-treated sows up to 104 hr after ovulation; by this time all eggs had reached the uterus in untreated sows.

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T. J. Hayden, H. L. Buttle, P. L. Rees, Susan V. Smith and Isabel A. Forsyth

Summary. Blood flow in the middle uterine artery was measured with electromagnetic blood flow probes, and placental lactogen in jugular and uterine venous plasma was estimated as total lactogenic activity using a radioreceptor assay. There was no circadian variation in uterine arterial blood flow in late pregnancy (Days 105– 124) and the pattern of blood flow varied between goats. Blood flow was quite stable for periods of up to 40 min although at other times a rapid fall (by up to 90%) was followed by a gradual recovery. These spontaneous changes lasting up to 30 min could not be consistently related to postural or behavioural changes. Acute decreases of about the same duration could also be induced by administration of adrenaline. In the short-term there was no association between uterine blood flow and total lactogenic activity in the peripheral circulation during spontaneous or adrenaline-induced depression of blood flow. More limited short-term observations on total lactogenic activity in the uterine vein also failed to show a relationship with blood flow in the uterine artery.

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F. B. P. Wooding, A. P. F. Flint, R. B. Heap, G. Morgan, H. L. Buttle and I. R. Young

Summary. In the ruminant placenta 15–20% of the trophectodermal epithelium consists of granulated binucleate cells (BNC). In the sheep the granules contain ovine placental lactogen (oPL). These cells migrate from the trophectoderm to form fetomaternal hybrid tissue from implantation to term.

The number of BNC, their percentage migration and the potential secretory activity of the syncytium they form were estimated by semiquantitative transmission electron-microscopical techniques after several surgical techniques and hormone or drug infusions.

BNC numbers decrease normally just before parturition, and this fall could be eliminated by fetal hypophysectomy or induced early by administration of tetracosactrin to intact or hypophysectomized fetuses. If only one twin was treated with tetracosactrin the placenta of the untreated twin did not show the fall in BNC numbers found in the other unless it died in utero some time before sampling. This indicates fetal control of BNC number and migration.

However, fetal catheterization, hypophysectomy, stalk section, adrenalectomy, infusion of mouse epidermal growth factor or bromocriptine had little or no effect on binucleate cell numbers or migration percentages. Maternal carunclectomy, ovariectomy, or epostane or bromocriptine administration also had no consistent significant effect.

Previous reports of degeneration of BNC structure plus a decrease in their number (with bromocriptine) or an increase in migration frequency (after adrenalectomy or stalk section) have not been confirmed by this study. The BNC migration delivers the oPL-containing BNC granules close to the maternal circulation but the variation in migration seems only loosely correlated with the reported maternal oPL concentrations.

The results indicate that BNC migration is independent of the hormonal milieu, but that BNC production is greatly modified by the hormonal changes just before parturition, with cortisol production by the fetus a possible primary cause.