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K. P. BLAND

It has frequently been suggested that the peripheral nervous system plays a part in the process of implantation and early pregnancy. Evidence for this was proposed by Nalbandov & St. Clair (1958) but much of this evidence is now open to alternative explanations (Anderson, Bland & Melampy, 1969). The study of implantation in a transplanted uterus would clarify the situation but attempts in the sheep have been unsuccessful (Niswender, Dziuk, Graber & Kaltenbach, 1970). Transplantation of the uterus ensures complete isolation from its original nerve supply and any reinnervation is almost certainly nonspecific.

Two-stage uterine autotransplantation was performed in five guinea-pigs by the method described by Bland (1970). The first stage involved the severing of the broad ligament down the entire length of both uterine horns and then suturing the mesometrial aspect of the uterus to the muscle of the body wall. When the animal had returned normally to

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K. P. Bland

Summary. Follicular growth in the normal oestrous cycle of the guinea-pig is biphasic. The first wave of follicular growth culminates on Days 10–11 while the second wave ends in ovulation.

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K. P. BLAND and B. T. DONOVAN

Summary.

Removal of the conceptuses (decidua+embryos) from the uterus of the guinea-pig between the 9th and 15th days after mating allowed the recurrence of oestrus at, or only slightly after, the time it would have occurred had not fertile mating taken place. The transfer of a single 6-day blastocyst to the uterus of unmated cycling animals resulted in pregnancy in three of six animals in which the cycles of the host and donor were synchronized. Normal development was never observed after transfer of 9- to 11-day implanted conceptuses (without associated decidua) to the uterus. Blastocysts and 9- to 10-day implanted conceptuses transferred to the spleen developed in eight of thirteen animals. The ectopic placental tissue did not prevent the normal recurrence of oestrus. Grafts developing from a single 11- to 12-day implanted conceptus in the spleen maintained the corpora lutea and delayed oestrus until after the 20th day in thirteen of twenty-four animals. The guinea-pig placenta appears to produce a systemically-active substance capable of neutralizing the luteolytic abilities of the uterus. This anti-luteolytic hormone probably acts only between Days 12 to 25 after mating.

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K. P. BLAND and B. T. DONOVAN

Summary.

Successful primary abdominal implantation and development has been induced in the guinea-pig by transection of the oviducts 1 to 3 days after mating although attempts made to induce tubal implantation by ligature of the utero-tubal junction failed.

Development also took place in four out of eighteen pre-implantation eggs (aged 4 to 5 days post coitum) transplanted into the kidney or abdominal muscle. In six cases, where post-implantation conceptuses (aged 9½ and 12 days post coitum) were transplanted into the spleen, testes or anterior chamber of the eye, growth and differentiation was observed on each occasion.

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S. N. Alwachi, K. P. Bland and N. L. Poyser

Summary. The concentration of prostaglandin (PG) F-2α was measured in different uterine and ovarian blood vessels between Days 12 and 16 of the oestrous cycle in 14 normal ewes. Concentrations of PGF-2α significantly higher than peripheral levels were found in the uterine vein (P < 0·002) and oviducal vein (P < 0·002). This suggests that an additional pathway for PGF-2α transfer to the ovary exists via the venous drainage passing alongside the oviduct.

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M. J. Blissitt, K. P. Bland and D. F. Cottrell

The ability of rams to discriminate between urine odour of oestrous ewes and urine odours from ewes at other days of the oestrous cycle was determined using operant conditioning techniques. Rams could discriminate between the odour of urine of oestrous ewes and the odours of urine from ewes at day 6 to day 1 before oestrus and from ewes at day 4 to day 10 after oestrus. Rams did not discriminate between odours of urine samples from different ewes in oestrus, or between urine odour of oestrous ewes (day 0) and urine odours from ewes at day 1 to day 3 after oestrus. These results support the hypothesis that ewes in oestrus produce an odour in urine that is detectable by rams.

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S. E. A. Abdel Rahim, K. P. Bland and N. L. Poyser

Summary. The insertion of a glass cannula into the uterine branch of the utero-ovarian vein, followed by disconnection of all other tissues between the uterus and the ovary containing the luteal tissue in non-pregnant sheep, was followed by a prolongation of luteal function. A pathway involving uterine venous blood alone is therefore insufficient to explain the transfer of PGF-2α from the uterus to the ipsilateral ovary. We suggest that lymph is also involved.