The growth of the pituitary and of the reproductive tract of Suffolk rams from birth to 168 days of age has been studied. Pituitary icsh and fsh concentrations were determined by bio-assay. The pattern of testicular androgen production has been examined using chemical and histological techniques and the relationship to spermatogenesis studied. Pituitary gonadotrophin content increased sharply from 42 days of age but was only weakly correlated with other parameters measured.The androstenedione : testosterone ratio was at its narrowest at birth; however, testosterone was the predominant androgen from birth onwards. Androgen concentration fluctuated but the total content increased with increase in testicular weight. Fructose was present in the seminal vesicles from birth and citric acid from 14 days; citric acid concentration was about one-tenth that of fructose. There was a significant correlation between testicular androgen content and the fructose and citric acid concentration and content of the seminal vesicles.Seminiferous tubule diameter was significantly correlated with most of the parameters measured. Testicular weight increased sharply from 42 days of age. Androgen production was present at birth and preceded spermatogenesis which began when testis weight exceeded 10 g, which was after 56 days of age. Spermatozoa were present in the seminiferous tubules at 112 days of age. J. D. Skinner et al. development of the seminal vesicles, prostate and bulbo-urethral gland, which in the late-term foetus resemble those in the castrated adult.The object of the present study was to examine the sexual development of the Suffolk ram from birth to 168 days of age. MATERIALS AND METHODSMaterial was provided by fifty-four Suffolk lambs allocated at random into six groups for slaughter at intervals of 14 days, from birth to 168 days. To obtain sufficient material for assay the numbers in the groups were as follows: ten at birth, eight at 14 days, six at 28 days, four from 42 to 70 days, two from 84 to 154 days, and six at 168 days. Histological observations on the testes of a 103-day-old ram foetus and a 105-day-old ram have also been included.The lambs were weighed before slaughter, after which the head was im¬ mediately removed, the pituitary gland removed, weighed, sealed in tin foil and frozen over solid C02 within 3 min of slaughter.The testes were then removed, weighed and slices taken for histology, the testes were then stored over solid C02. The amount of testosterone and androstenedione in the testes was estimated later. The remainder of the tract was dissected out, the accessory glands weighed individually, slices taken for histology and the seminal vesicles then stored over solid C02. The amount Sexual development in the ram 465 were evaporated to dryness and preliminarily chromatographed using thin-layer chromatography, medium Silica-gel GF 254 and solvent system CHCl3:EtoAc (2:1). This step finally removed contaminating substances which would otherwise have interfered with the resolution of the paper chromatograp...

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Male rock elephant shrews, Elephantulus myurus, showed active spermatogenesis throughout the year but had significant reductions in testis and prostate size, the proportion of interstitial cells and sperm numbers and viability from April to June, when no pregnant females were recorded. Rock elephant shrews have relatively small testes and extragonadal sperm reserves compared to many similar–sized mammals

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This paper evaluates the effects of the artificial introduction offcline panleucopaenia (FPL) as a primary control measure ofa feral cat population on the sub-Antarctic Marion Island (46 54'S,3T4S'E). (2) The population decreased from an estimated 3409 cats in 1977 (introduction of control factor) to 615 (S.E. = 107) ca ts during 1982, suggesting an annual rate of decrease 0129%. (3) Litter size decreased and the age structure changed significantly because ofa decrease in subadult numbers. Age specific mortality rates were higher but followed the same pattern as in 1975 because there were fewer subadults but the same age structure of adults. (4) The intrinsic rate of increase, as suggested by the survival and fecundity schedules of the: population, was higher in 1975 owing to a greater proportion of adults and a higher fecundity in age class II. (5) Antibody titres ofFPL were lower in 1982 than in 1978 which illustrates that FPL did afTect the cat population but is no longer spreading effectively. FPL was independent of feline herpes (FVR), an endemic disease of the cat population. and FPL was, therefore, directly responsible for the decrease in cat population density. (6) During 19R2 the cat population showed a decrease of 8% year-I, whieh indicates stabilizing of the negative growth rate. This observation was supported by lower titres of FPL.