Chromatin condensation and morphometry of the bovine sperm head after in vitro sperm selection and capacitation

Abstract

Methods of sperm selection and concentration are used to improve efficiency in obtaining viable embryos from in vitro fertilization procedures. Eighteen semen samples were submitted for selection with Percoll gradient and swim-up methods, followed by in vitro sperm capacitation with heparin, to assess the effect of selection method on chromatin condensation and sperm head morphometry. Smears were made at each stage of the process and stained with toluidine blue (TB). Digital images were analysed using computer algorithms developed with Scilab environment. After selection with either the Percoll gradient method sperm had less condensed chromatin. The swim-up method selected for smaller, more symmetrical heads with less variation in size when compared to semen samples that underwent no selection or were selected with the Percoll gradient method. The sperm also exhibited less condensed chromatin and more uniform head shape after heparin-induced capacitation.

Keywords:

• sperm
• selection
• capacitation
• chromatin
• morphometry

Acknowledgements

The authors thank the CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) and the FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais) for providing financial support.