[The electron microscopic analysis of synaptonemal complexes in male hybrids]

Cytogenetic studies of sterile male F1 hybrids may be helpful for the understanding of genetic bases of Haldane's Rule. The main purpose of this review is to provide several explanations for various meiotic abnormalities associated with impaired fertility. Results of cytogenetic studies of gametogenesis in vertebrates (mainly mammals) performed using electron microscopy lead to the conclusion that abnormal morphology of synaptonemal complexes is one of the main factors underlying sterility of hybrid males in mammals. Various abnormalities of synaptonemal complexes have been described in male hybrids of primates (lemur), small rodents (hybrids of laboratory mice with wild mice, as well as voles, mole-voles, hamsters, rats, and gerbils), and carnivores (silver fox, mustelids), as well as in the shrew, cattle hybrids, buffalo, and fish.