Conventional chromosomal preparations of the Brazilian sidenecked turtle Phrynops hogei indicate the karyotype of this species (diploid number 2n = 58; fundamental number FN = 64) is identical to that reported for other members of the genus. Electron microscopic analysis of whole-cell complements of synap- tonemal complexes corroborated the karyotypic description and provided definitive resolution of the aero- centric condition of the microchromosomes. Additionally, this approach provided a continuous sequence of prophase I nuclei which enabled detailed description of chromosomal behavior from leptonema through dia- kinesis and the sequence of centriolar replication.
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Acknowledgments. Critical reviewso f the manuscript were provided by J. L. Carr and J. W. Sites, Jr. The researchw as supported in part by grants from the US National ScienceF oundation(BSR-8614569 and BSR-8822751), the US National Institutes of Health (GM-27014), and the Texas Agricultural Research Foundation (Expanded Research Area).