Sperm head shaping in ratites: New insights,yet more questions |
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| Affiliation: | 1. Electron Microscope Unit, Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa;2. Department of Anatomy and Physiology, Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, South Africa;1. Department of Animal Sciences, University of Stellenbosch, Matieland 7602, South Africa;2. School of Animal Biology M085, Faculty of Natural and Agricultural Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;3. Department of Genetics and Animal Breeding, Warsaw University of Life Sciences, Ciszewskiego 8, 02-786 Warsaw, Poland;4. Department of Biology, Lund University, SE-223 62, Lund, Sweden;5. Directorate Animal Sciences: Elsenburg, Private Bag X1, Elsenburg 7607, South Africa;1. School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, WA, U.S.A.;2. Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, U.S.A.;3. Cornell Lab of Ornithology, Cornell University, Ithaca, NY, U.S.A.;4. Department of Developmental Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany;1. Laboratory of Signal Transduction, Institute for Research in Biomedicine, Health Sciences Program, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal;2. Hospital Infante D. Pedro E.P.E., Aveiro, Portugal;3. Kinexus Bioinformatics Corporation, Vancouver, British Columbia, Canada;4. Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada;1. Department of Animal Sciences, University of Stellenbosch, Matieland 7602, South Africa;2. School of Animal Biology M085, Faculty of Natural and Agricultural Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;3. Directorate Animal Sciences, Elsenburg, Private Bag XI, Elsenburg 7607, South Africa |
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| Abstract: | Head shaping in mammalian sperm is regulated by a number of factors including acrosome formation, nuclear condensation and the action of the microtubular manchette. A role has also been suggested for the attendant Sertoli cells and the perinuclear theca (PT). In comparison, relatively little information is available on this topic in birds and the presence of a PT per se has not been described in this vertebrate order. This study revealed that a similar combination of factors contributed to head shaping in the ostrich, emu and rhea, although the Sertoli cells seem to play a limited role in ratites. A fibro-granular structure analogous to the mammalian PT was identified, consisting of sub- and post-acrosomal components. The latter was characterized by stage-specific finger-like projections that appeared to emanate from the cytoplasmic face of the nuclear envelope. They were particularly obvious beneath the base of the acrosome, and closely aligned, but not connected to, the manchette microtubules. During the final stages of chromatin condensation and elongation of the sperm head the projections abruptly disappeared. They appear to play a role in stabilizing the shape of the sperm head during the caudal translocation of the spermatid cytoplasm. |
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| Keywords: | Ratites Spermiogenesis Manchette microtubules Acrosome formation Chromatin condensation Perinuclear theca |
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