Research Articles (Botany and Zoology)

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Browsing Research Articles (Botany and Zoology) by Author "Ackerman, D. J."

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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.