Proximal Centriole-like
The proximal centriole-like or PCL is an atypical type of centriole found in the sperm cells of insects. The PCL name is due to some similarity to the Proximal centriole found in Vertebrates sperm and the hypothesis that the two structures are Homology (biology), homologous. The PCL is an atypical type of centriole because it does not have microtubules, a defining feature of centrioles. However, the PCL is a type of centriole for several reasons. (1) the PCL formation is dependent upon the same genetic pathway that mediates the initiation of centriole formation. (2) The PCL is composed of centriolar proteins. (3) After fertilization, the sperm PCL function like a centriole. The PCL recruits pericentriolar material (PCM) forming a centrosome that acts as a microtubule-organizing center (MTOC). The PCL also serves as a platform to form a typical centriole in the zygote, as expected from a centriole. Also, the PCL is essential to form one of the two Spindle apparatus, spindle poles of th ...
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Centriole
In cell biology a centriole is a cylindrical organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells, but are not present in conifers (Pinophyta), flowering plants (angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and ''Ginkgo''. A bound pair of centrioles, surrounded by a highly ordered mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome. Centrioles are typically made up of nine sets of short microtubule triplets, arranged in a cylinder. Deviations from this structure include crabs and ''Drosophila melanogaster'' embryos, with nine doublets, and ''Caenorhabditis elegans'' sperm cells and early embryos, with nine singlets. Additional proteins include centrin, cenexin and tektin. The main function of centrioles is to produce cilia during interphase and the aster and the spindle during cell divisio ...
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