Synaptonemal complex karyotype of zebrafish.

Meiotic cells of zebrafish have been prepared to show synaptonemal complexes (SCs) by light and electron microscopy. Completely paired SCs from both spermatocytes and oocytes were measured to produce an SC karyotype. The SC karyotype resembles the somatic karyotype of zebrafish and has no recognisable sex bivalent. Measurements of total SC length indicate that SCs grow longer and develop centromeres during pachytene. Oocytes consistently have longer SCs than spermatocytes, presumably correlated with the reported higher recombination frequency in females than in males.