Publications by authors named "S F Sowerbutts"

Merino ram lambs were actively immunized against oestradiol-6 (o-carboxy methyl) oxime-BSA conjugate at 14 weeks of age and received a booster injection 4 weeks later. This treatment led to an increase in plasma concentrations of gonadotrophin and tended to enhance the increase in testicular volume until 26 weeks of age; however, testis size and mass at time of castration (30 weeks of age) were similar to values in BSA-immunized lambs. Detrimental effects were observed in some oestradiol-immunized ram lambs, for example a steep decline in testicular volume towards the end of the experiment, the presence of large vacuoles within the seminiferous epithelium and, in one lamb, few germ cell at 30 weeks of age.

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The long-term effects of active immunization against testosterone were studied in rams, with particular reference to blood concentrations of gonadotrophin and testosterone, spermatogenesis, testis blood flow and mating behaviour. Ten 18-month-old Merino rams, kept on pasture, were studied for 1 year. Every 2 months, five rams received injections of BSA in Freund's adjuvant and five other rams were treated with testosterone-3(o-carboxymethyl)oxime-BSA as immunogen.

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After removal of the scrotal skin, one testis of each of 12 adult anaesthetized rams was kept at 33 degrees C for 60 min, then heated either to 36 degrees C for 60 min and then to 39 degrees C for 60 min, or to 36 degrees C for 120 min and then returned to 33 degrees C for 100 min, while the other testis was maintained at 33 degrees C. Flow of testicular blood plasma was measured every 10 min using the technique of dilution of sodium p-aminohippurate. When the temperature of the testis was raised to 36 degrees C, flow of blood plasma gradually increased and reached a higher than normal rate at the end of the first hour, without any further increase during the second hour.

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Fertilization rate and embryonic mortality were assessed in 636 ewes inseminated in each uterine horn with 50 x 10(6) frozen spermatozoa from four control rams and from four rams submitted to a moderate (1.4-2.2 degrees C), but repeated, intermittent (16 h/day for 21 consecutive days) increase in their subcutaneous scrotal temperature by means of scrotal insulation.

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