The aim of the study was to develop quantitative methods to evaluate disturbances of meiosis at the stages of
prophase I, namely preleptotene, leptotene, zygotene, pachytene, diplotene, dictyotene, diakinesis; metaphase
I and II, anaphase I and II, telophase I and II) as well as unidentifiable degenerating female and male mammal
gametes. Methods for the quantitative evaluation of the stages of meiosis have been developed. The results
of studies of female and male meiosis stages violation under chemical (thiophosphamid, 17-β-estradiol,
alcohol, nicotine), physical and biological factors are presented. These factors lead to the decrease in the
number of gametes, block of meiotic stages, increasing frequency of gamete degeneration, and infertility.
Key words: mitosis, meiosis, prophase, metaphase, anaphase, telophase, ovaries, testes, oocytes, spermato-