Cheng E Y, Chen Y J, Gartler S M
Department of Obstetrics and Gynecology, University of Washington, Seattle, USA.
Cytogenet Cell Genet. 1995;70(3-4):205-10. doi: 10.1159/000134034.
We have used chromosome 18-specific painting probes to analyze early stages of oogenesis in two human trisomy 18 fetuses. At leptotene, a diffuse, nonlinear chromosomal fluorescence was detected as one (27%), two (42%), or three (31%) signals in 534 cells. The variation in size of these signals implies the possibility of associations between homologs prior to zygotene. At pachytene, about 75% (339/453) of the cells had a trivalent configuration, and almost half of these cells exhibited almost complete triple synapses. Approximately 24% of the pachytene cells demonstrated a bivalent:univalent configuration, and 1% exhibited complete asynapsis. Our data imply that triple synapses may be a regular feature of meiosis involving multivalents.
