Confocal scanning laser microscopy examination of bovine vaginal fluid at oestrus

This article reports the study of the structural elements of bovine vaginal fluid at oestrus using a confocal scanning laser microscope (CSLM) to examine samples collected from 10 lactating cows at the time of insemination. The filamentous glycoproteins, which form the structural component of vaginal fluid, were stained with fluorophore acridine orange for 10 min. This microscopy technique permits visualization of a network of non-oriented filaments of different thickness in a three-dimensional array. This arrangement was repeated throughout the sample and was common to all samples. Interfilament spaces varied in width between cows and ranged from 1 to 20 microns. The present results provide a new, non-aggressive technique for the study of biological samples that show hydrogel-like behaviour. Due to its simplicity, the CSLM technique proposed offers the advantages of (1) providing realistic images of vaginal fluid structure, free from artifacts arising from sample preparation, and (2) the possibility of observing specimens shortly after collection. CSLM proved to be a useful tool for the examination of vaginal fluid and may also serve as a good control for artifacts associated with scanning electron microscopy procedures.