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The male gametophyte of the water fern Marsilea vestita develops to produce 32 ciliated spermatozoids within the microspore wall, in approximately 11 h after the dry spore is placed into water. The gametophyte starts out as a single cell that undergoes nine successive mitotic divisions in specific planes to produce 32 spermatids and seven sterile jacket cells. After the divisions are completed, each spermatid undergoes a complex differentiation process, which includes nuclear condensation and elongation, cell coiling, the de novo formation of basal bodies from a particle known as a blepharoplast, and ciliogenesis. Each mature spermatozoid has approximately 140 cilia attached to the dorsal side of a complex spirally shaped cytoskeleton. Shown is a phase-contrast microscopic image of a semithick plastic section of a gametophyte fixed after 8 h of development. The image is overlaid with fluorescence from blue DAPI staining of nuclei and red anti-centrin antibody staining of the basal bodies. The basal bodies are accumulating on what will become the dorsal face of each gamete. The elongated nuclei of the spermatids contrast sharply with the irregularly shaped nucleus of a centrally situated sterile cell. See the article by van der Weele et al. on p. 3711 of this issue of MBC. (Image: Corine M. van der Weele, Department of Cell Biology and Molecular Genetics, University of Maryland)

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