Browsing by Author "Ackerman, D. J."

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    Sperm abnormalities associated with high copper levels in impala (Aepyceros melampus) in the Kruger National Park, South Africa
    (1999) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.; Grobler, D. G.; Reinecke, S. A.
    The morphology of spermatozoa may be affected by very low concentrations of pollutants in the environment, and sublethal effects of toxic substances can be detected by studying the sperm of an animal. Sperm were collected from 50 impala (Aepyceros melampus) from a conservation area in South Africa and studied ultramicroscopically. Thirty-two samples were obtained from animals close to a copper mine, while 18 represented animals from an unpolluted area and held in captivity. Liver samples from all these animals were analyzed for their copper content. The findings from 12 animals kept in captivity and fed on a diet to which copper was added correlated with the findings from the field study. The general condition of the animals as expressed by the fat content of the bone marrow from the area exposed to copper contamination was affected detrimentally in comparison to the animals from the uncontaminated area. High percentages of sperm with neck vacuoles were found in all animals with high liver copper levels. A statistically significant correlation is demonstrated between the percentage of impala sperm with vacuoles in the neck region and the copper concentrations in this group of animals.
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    Transmission electron microscopic observations of acrosome and head abnormalities in impala (Aepyceros melampus) sperm from the Kruger National Park
    (AOSIS, 1997) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.
    Sperm morphological features play an important role in semen evaluation. Exposure to a variety of chemical compounds, especially environmental endocrine disrupters, elicit abnormalities in sperm of certain species. Baseline data on ultrastructure of normal sperm as well as abnormalities observed concomitantly, are required before causal links between such substances and abnormalities can be established. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy to document normal sperm features and abnormalities. The following abnormalities of the acrosome and sperm head were documented from micrographs: Loose acrosome in various stages of disintegration, lip forming of the acrosome; bizarre head, crater defect, poor condensation of the nucleus and the Dag defect. The observed abnormalities were very similar to those reported for other members of the Bovidae. Different forms of a hollow sphere, formed by the nucleus and covered by an abnormal acrosome have not previously been described for other species.
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    Transmission electron microscopic observations of flagellum abnormalities in impala (Aepyceros melampus) sperm from the Kruger National Park
    (AOSIS, 1997) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.
    Sperm must remain motile in order to reach and penetrate the ovum and defects in the ultrastructure of the tail can have an adverse influence on motility. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in. the Kruger National Park and studied by transmission electron microscopy to document sperm abnormalities. The following abnormalities of the flagellum were documented from micrographs: abnormal baseplate and neck attachments; neck vacuoles and displaced organelles; double or short flagella; bent flagella; principal-piece vacuoles; displaced axoneme and the Dag defect. The implications of these abnormalities for sperm motility are discussed.
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    A transmission electron microscopic study of impala (Aepyceros melampus) sperm from the Kruger National Park
    (AOSIS, 1996) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.
    Since knowledge of sperm morphology can play an important role in semen evaluation and fertilisation, baseline data are required. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy. The morphology of normal sperm was documented. The impala sperm shares characteristics with other members of the Bovidae. The occurrence of appendages on the cytoplasmic droplet of the flagellum of impala sperm is described for the first time. A total of 31 micrographs, showing typical features of impala sperm, in sections through various planes of the sperm, are presented.