This review discusses various techniques of storage of avian genetic resources. Semen cryopreservation still seems to represent one of the most effective and feasible methods for preservation of genetic resources. Various cryoprotective agents, cooling rates and semen packaging methods are discussed. The use of ovarian tissue, embryonic cells, such as primordial germ cells (PGCs) or blastodermal cells, is the most promising approach because both male and female genetic information can be preserved. A relatively innovative technique; transplantation of cryopreserved testicular cells into adult animals with subsequent production of donor-derived progeny is also mentioned. This transplantation method may contribute to the preservation of endangered avian species and to maintaining their genetic variability.

DNA replication in the spermatogonial cells of Schistocerca gregaria and Gryllotalpa fossor has been analysed. This study has demonstrated the presence of at least two discrete populations of spermatogonial cells in both the insects with different intermitotic timings. The replication pattern of the sex chromosome in Schistocerca seems to be dependent on the pycnosity status, whereas, in Gryllotalpa, it is independent of the condensation pattern.