Changes in motility,
ultrastructure, and fertilization capacity of striped bass Morone
saxatilis spermatozoa following cryopreservation
S. He, L. Curry Woods, III-2004
Aquaculture, 236(1-4): 677-686
Abstract:
In the present study, motility, ultrastructure and
fertilization capacity of fresh and cryopreserved striped bass spermatozoa
were investigated in order to evaluate semen dilution ratio, freezing rate
and cryomedia. Four dilution ratios (semen/cryomedia), and four freezing
rates were evaluated on the basis of post-thaw sperm motility. The dilution
ratio of 1:3 yielded the highest (P<0.05) post-thaw motility.
Sperm cryopreserved with a freezing rate of −40°C min−1
resulted in a higher percentage of motile sperm (P<0.05) than
other lower freezing rates we examined. Six cryomedia with various dimethyl
sulfoxide (DMSO) and glycine concentrations were tested for their influences
on ultrastructure, post-thaw motility and fertilizing capacity of
cryopreserved sperm. The ultrastructural results revealed that the plasma
membranes of spermatozoa were better protected with the higher DMSO
concentrations we examined. Two cryomedia containing 5% or 7.5% DMSO, both
with glycine added, resulted in the highest (P<0.05) post-thaw
motility compared with other cryomedia without glycine. The percentage of
eggs fertilized with sperm cryopreserved in six cryomedia ranged from 26±2.1%
(2.5% DMSO without glycine) to 54±5.6% (7.5% DMSO with glycine), which were
equivalent to 44% and 90% of fresh semen controls. No differences (P>0.05)
were detected in the percentage of eggs fertilized among DMSO concentrations
that did not contain glycine, although post-thaw motility did vary
significantly (P<0.05) in these treatments. These results suggest
that adding glycine to our basic cryomedia containing DMSO increases the
fertilization capacity of these cryopreserved spermatozoa.
(Department of Animal and Avian Sciences, University
of Maryland, College Park, MD 20742, USA, e-mail of L.C. Woods, III: curry@umd.edu)