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    ABSTRACT: This article reviews the remarkable life and major scientific achievements of the reproductive biologist M.C. Chang. His scholarly career progressed from university in Peking, via Edinburgh, Scotland, and Cambridge, England, to the newly founded Worcester Foundation for Experimental Biology in Massachusetts. At each stage, the hand of fate is noted as are the support and encouragement of key professors. Chang's own contributions on capacitation of spermatozoa, in vitro fertilisation of mammalian eggs, and transplantation of oocytes and embryos are all brought out, as is his essential input to the creation and development of a steroid contraceptive pill. He strongly encouraged young reproductive biologists who worked in his laboratory, and applauded the world-wide distinction of his student and associate, R. Yanagimachi, as a specialist in mammalian fertilisation. Finally, Chang's continued feelings towards his homeland are contrasted with the reality of his American life after 1945, itself a study in poignancy.
    No preview · Article · May 2013 · Human Fertility
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    ABSTRACT: Deep body temperature in mammals is generally but incorrectly regarded as uniform. Alterations of temperature in oviducts and preovulatory Graafian follicles may play a vital role in gamete maturation, fertilization and early embryonic development. At a molecular level, the conformation of regulatory proteins is susceptible to changes in temperature. Deviation from physiological temperature during IVF procedures could thereby exert a profound influence on patterns of gene expression as the embryonic genome unfolds during early cleavage stages and act to generate specific anomalies. Systematic studies are urgently required. The temperature of internal body organs in mammals such as rabbits and humans is widely regarded as uniform, but this is not correct. Temperatures in reproductive tissues such as ovaries and oviducts vary according to the stage of a menstrual or oestrous cycle. Such changes in temperature are thought to be critically involved in the maturation of eggs and spermatozoa and thus in events shortly before and after fertilization. Proteins in the cytoplasm and nuclei of eggs and very young embryos respond to small shifts in temperature by changing their three-dimensional shape. Conformational modifications in regulatory proteins in the nucleus would influence patterns of gene expression in developing embryos and may, when perturbed, alter the sexual phenotype of an individual. In the practical context of IVF, studies are needed of the influence of culturing gametes and embryos at different temperatures and ranges of temperature on the patterns of gene expression in preimplantation embryos.
    No preview · Article · Jan 2012 · Reproductive biomedicine online
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    ABSTRACT: After recalling male gonadal physiology in respect of tissue temperatures within the scrotal sac, and raising questions concerning abdominal testes, attention turned to mature Graafian follicles and ovarian stroma. Temperature gradients between such tissues were summarized for human, rabbit, pig, and cow, and generally fell in the range of 1.3-1.7 degrees C: follicles were always cooler than stroma. Measurements were made principally by means of a thermo-sensing camera at midventral laparotomy, but also using microelectrodes or thermistor probes sited in the follicular antrum of rabbits and pigs, respectively. When thermo-imaged under the fimbriated extremity of the Fallopian tube, mature pig follicles and stroma could still be distinguished. Such follicles cooled slightly more rapidly during the first 10 s of a 60-s recording interval, after which curves for the two tissues remained parallel. Arresting ovarian blood supply for 5 min had a negligible influence on the temperature differentials. Endoscopy in three models recorded mean differentials of 0.6 +/- 0.1 degrees C - 1.1 +/- 0.1 degrees C between follicles and stroma, but such follicles had not attained mature diameter. Temperature gradients were thought to be generated at least in part by endothermic reactions within mature follicles, reflecting hydration of large extracellular matrix molecules such as proteoglycans. A contribution to the cooling process from the products of leukocyte activity in the follicle wall and antrum could also be involved. Temperature gradients would be maintained locally by counter-current heat exchange mechanisms and, in this context, the microvasculature and lymphatic flow of individual follicles were found to be appropriate. Observations on the temperature of preovulatory follicles appear relevant to procedures of in vitro maturation and in vitro fertilization.
    No preview · Article · Jun 2006 · Microscopy Research and Technique
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