view - Department of Reproduction, Obstetrics and Herd Health

CHAPTER 1.1
Fig. 7. Equine spermatozoa labeled with the fluorescent staining FITC-PSA with (a) representing an
intact acrosome (green fluorescence over the entire acrosomal region) and (b and c) reacted
acrosomes ( b = no green fluorescence over the acrosomal region, c = thin band of green
fluorescence over the equatorial region of the sperm head) .
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The capacitation and acrosome status analysis can be applied to predict the fertility in two
possible ways. Firstly, by looking at the percentage of acrosome reacted and capacitated sperm in
the sample, since acrosome reacted sperm can no longer fertilize an oocyte and capacitated sperm
has a reduced longevity (Watson, 1995). Therefore, their numbers in a sperm sample should be low.
Secondly, the ability of sperm to undergo capacitation and the acrosome reaction in vitro as a
response to stimulation can be evaluated. Since the latter approach simulates essential functions of
sperm in order to achieve fertilization, this may be a more valuable approach. However, the
induction of capacitation and acrosome reaction has been described using different techniques, such
as using HCO3-/CO2-free Tyrodes medium with addition of Ca2+ ionophores (Rathi et al., 2001) or by
procaine treatment (McPartlin et al., 2009), nevertheless, these methods lack a good reproducibility.
DNA analysis
The value of DNA analysis in predicting fertility is not uniformly accepted, particularly since
contradictory results can be found in literature. However, DNA integrity of the sperm may be more
important than previously thought and may be equally important as classical sperm parameters since
“in contrast to the traditional measures of viability, morphology and motility that examine the carrier,
DNA tests assess the content of the package” (Makhlouf and Niederberger, 2006). A wide range of
diagnostic tests is available for analyzing the sperm’s DNA, and these different tests measure
different aspects of DNA damage. The DNA breaks can be analyzed either directly, or alternatively,
the susceptibility of the DNA to denaturation can be analyzed.