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A. S. PARKES

When Dwight Ingle invited me to contribute to an issue of Perspectives in Biology and Medicine to be inscribed in honour of Gregory Pincus, I was puzzled as to how I could best collaborate. I had met Pincus only sporadically, mainly on his visits to England, and I had visited his headquarters at the Worcester Foundation only once, in its early days. I was, however, most anxious to participate because of my profound admiration for the man and, after some thought, decided that an illustrated account of my personal contacts with him might be of interest and would give me the opportunity of paying a personal tribute.

I first met Pincus on the train between Cambridge and London, when a wild-looking young man introduced himself to me in the restaurant car, explaining that he was working for a year at the Agricultural Research Council's Unit in

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A. S. PARKES

INTRODUCTION This is the Fifth Oliver Bird Lecture and it is appropriate, therefore, to attempt a rather more general survey than has been the case with the earlier lectures. The Oliver Bird Lecture and the Oliver Bird Prize were instituted to review and stimulate work bearing on the control of conception in man. Such review and stimulation was badly needed. Four years ago, when the Oliver Bird Trust came into being, no organized clinical trials of contraceptive methods were going on in this country, and those working on the physiology of reproduction were giving little thought to possible applications of their work to the control of human fertility. Yet, on a global scale, the need for such control by simple and effective methods was becoming more urgent every year. In many countries, population is increasing at an unprecedented rate and, what is more, at an accelerating rate. This increase
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A. S. PARKES and H. M. BRUCE

Summary.

Newly mated female mice were placed singly for periods of up to 3 days in boxes recently vacated by five males of a different strain (alien males). When the soiled boxes were renewed twice daily, the females showed pregnancy-block to the same extent as when placed in the proximity of alien males for similar periods. When the soiled boxes were renewed once daily, the incidence of pregnancy-block was much reduced. An equal amount of disturbance, caused by similarly transferring the females to clean cages, did not affect the incidence of pregnancy.

These results support previous work in indicating that the smell of the alien male is the operative factor in pregnancy-block, and further suggest that the odorous substances involved are highly evanescent.

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D A Zysling, S-U Park, E L McMillan and N J Place

Many seasonal breeders time their reproductive efforts to specific times of the year to ensure adequate resources for the production and care of young. For long-day (LD) breeders, females born before the summer solstice (LDs) reach sexual maturity quickly and often breed that same year, whereas females born after the summer solstice (short days (SDs)) may delay reproductive development to the following spring when environmental conditions are favorable for reproduction. In Siberian hamsters, development in SD is associated with structural and functional differences in the ovary compared with females held in LD, including a greater number of primordial follicles and an abundance of hypertrophied granulosa cells (HGCs), which are immunoreactive for anti-Müllerian hormone. The goal of this study was to determine whether SD-induced gonadotropin suppression is responsible for these phenotypic differences. Gonadotropin levels were suppressed in LD hamsters using the GNRH antagonist acyline. Conversely, to determine whether the SD ovarian phenotype is completely reversed by gonadotropin stimulation, recombinant human FSH (rhFSH) was administered. Our treatments were successful in mimicking FSH concentrations of the opposite photoperiod, but they did not produce a comparable change in the ovarian phenotype. Most notable was the lack of HGCs in the ovaries of acyline-treated LD females. Similarly, HGCs were maintained in the ovaries of SD females treated with rhFSH. Our data suggest that gonadotropins alone do not account for the SD ovarian phenotype. Future studies will determine whether SD-induced changes in other factors underlie these phenotypic changes.

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D Corcoran, T Fair, S Park, D Rizos, O V Patel, G W Smith, P M Coussens, J J Ireland, M P Boland, A C O Evans and P Lonergan

In vivo-derived bovine embryos are of higher quality than those derived in vitro. Many of the differences in quality can be related to culture environment-induced changes in mRNA abundance. The aim of this study was to identify a range of mRNA transcripts that are differentially expressed between bovine blastocysts derived from in vitro versus in vivo culture. Microarray (BOTL5) comparison between in vivo- and in vitro-cultured bovine blastocysts identified 384 genes and expressed sequence tags (ESTs) that were differentially expressed; 85% of these were down-regulated in in vitro cultured blastocysts, showing a much reduced overall level of mRNA expression in in vitro- compared with in vivo-cultured blastocysts. Relative expression of 16 out of 23 (70%) differentially expressed genes (according to P value) were verified in new pools of in vivo- and in vitro-cultured blastocysts, using quantitative real-time PCR. Most (10 out of 16) are involved in transcription and translation events, suggesting that the reason why in vitro-derived embryos are of inferior quality compared with in vivo-derived embryos is due to a deficiency of the machinery associated with transcription and translation.