Summary Six horses with monorchidism, identified at surgery for cryptorchidectomy, are reported. All six presented with a single scrotal testis. Following surgical removal of one testis, they were either hormonally, anatomically or behaviourally determined to be geldings. Three other horses reported in the literature are reviewed. Of these nine cases of monorchidism, eight were thought to be caused by testicular degeneration and one by testicular agenesis. The vaginal process was present in all of the former and absent in the latter. The left side was involved in five of these eight horses. In seven, the epididymis was absent and, in the remaining two, only the epididymal tail was present. The condition was thought to be congenital in the six horses in this series. A surgical approach to identify accurately monorchid horses is described.

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The effects of polymer modification on microstructure, morphology, and failure modes of asphalt binders and their concretes were investigated using various test methodologies that have been newly developed or modified. Results from the good and bad samples (i.e., a new Marshall concrete specimen and an aged road core, flexible pavement that showed signs of stripping, respectively) confirmed the reliability and applicability of the test methods. Two different viscosity-graded asphalt binders, AC-5 and AC-10, with two types of network thermoplastics, styrene-butadiene-styrene and styrene-ethylene-butadiene-styrene block copolymers, were studied for void morphology, binder phase morphology, statistical void image analysis, and failure modes as a function of polymer concentration and test temperature. One of the most striking results is that a highly entangled fibrillar network structure has been observed from both straight and polymer-modified asphalt binders after an electron beam etching. It was also observed that the morphology of the network altered with prestraining or binder aging. Void morphology and statistical void analysis were well characterized with the methods developed, but no significant effect of polymer modification was observed. From the fracture studies, however, the polymer modification indicated strong influence on both microdeformation behavior and failure mode of the asphalt concretes.