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EN
Mammal spermatozoa demonstrate a wide morphologic variety resulting from the different histories of their genetic development. Alongside a general sperm classification including a head and tail there are significant differences between shape and size of head and length of tail between particular species. Regarding species peculiarity, the differences in the sperm can be determined not only with the quantity of genetic material in testicles possessing a particular shape and different grade of flattening, but also with: size, grade of acrosom diversity and other morphometric features of the remaining gamete parts: the neck and midpiece. During sperm morphology estimation it is crucial to consider the breeding season of particular species, because the quality of semen in moderate and cool climate animals is strongly influenced by the length of the day. While studying semen characteristics for particular species of wild animals, on account of differences in processes of spermatogenesis determined by a variety of factors, in the majority of cases the useful spermiograms for domestic animals cannot be applied.
11
Content available Herpetofauna Rezerwatu Przyrody "Parkowe"
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EN
The aim of this review was to present the role of embryonic genome activation in zygote formation and in early embryonic development. Moreover, the authors emphasize the influence of selected factors on the quality and development of embryos in preimplantation stages. In recent years, reproductive biologists have focused on such processes as the regulation of oogenesis, folliculogenesis and morphogenesis. Thanks to the development of molecular biology and reproductive bio-techniques, it was possible to demonstrate the important role that activation of the embryonic genome plays in the above processes. Embryonic genome activation is a specific process whose origins dependent on the species of the mammal. In some species, activation of the embryonic genome begins in the 2-cell-stage embryo, while in others it begins during the 5th cell division. Molecular changes associated with embryonic genome activation play a crucial role in the morphological structure of the embryo. However, most of these morphological structure changes occur in the cell nucleus following the formation of nucleolus precursor bodies (NPB). It has also been suggested that epigenetic changes, such as the methylation and demethylation of embryonic DNA or the acetylation of histones, may play an important role in embryonic genome activation. There is little literature describing the influence of sperm RNA on basic semen parameters, the ability of a spermatozoon to fertilize an oocyte, or early mammalian embryonic development. This review discusses these parameters, as well as the role of micro-engineering and microfluidic research in the assessment of embryo quality.
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