Hypotheses for the functions of intercellular bridges in male germ cell development and its cellular mechanisms
Journal of Theoretical Biology 229(2004)139-146，-0001，（）：
In oogamous reproduction of multicellular organisms, a striking phenomenon is the prevailing synchronous development of male germ cells connected by wide intercellular bridges (IBs, 0.1-2mm), which is well conservedin both animal andplant species ranging from algae to human. In the literature, IBs are believed either to allow genetically segregated haploid spermatids to share diploid gene products after meiosis, or to mediate rapid transfer of some vital signals or nutrients. Although intercellular sharing of gene transcripts has experimental evidences, these hypotheses are still not satisfactory. To explore the unknown roles of IB, we assume that developing male germ cells may be especially sensitive to stochastic gene expression to become heterogeneous. To achieve best gamete quality, such heterogeneity must be eliminated so that relatively uniform gametes with normal functions can be produced. Development within a common syncytium may be the only way for this purpose. The process may require not only the intercellular exchange of a few molecular signals but also the mixing of protoplasm between the connectedcells so that they have similar levels/states of mRNAs, proteins andorganelles, which can be achievedonly through wide IBs. This hypothesis can explain some quite intriguing aspects of male gametogenesis and provide unique predictions that can be tested experimentally.
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