SPERM MEMBRANE FUNCTIONAL INTEGRITY AND RESPONSE OF FROZEN-THAWED BOVINE SPERMATOZOA DURING THE HYPOOSMOTIC SWELLING TEST INCUBATION AT VARYING TEMPERATURES
Jr. Correa et al., SPERM MEMBRANE FUNCTIONAL INTEGRITY AND RESPONSE OF FROZEN-THAWED BOVINE SPERMATOZOA DURING THE HYPOOSMOTIC SWELLING TEST INCUBATION AT VARYING TEMPERATURES, Theriogenology, 47(3), 1997, pp. 715-721
The objective of this study was to assess the sperm membrane integrity
and permeability of frozen-thawed bovine spermatozoa, processed at va
rying temperatures during and after thawing by exposing the spermatozo
a to standardized hypoosmotic conditions. The hypoosmotic swelling (HO
S) test was employed to measure changes in sperm membrane functional s
tatus and permeability. Frozen specimens (from 5 bulls) were thawed at
37 degrees C for 10 sec and transferred to a water bath at 37 (Aliquo
t 1), 21 (Aliquot 2) or 5 degrees C (Aliquot 3) to complete thawing(1
to 2 min). The specimens were maintained and processed at these temper
atures for additional 5 to 10 min. Specimens were slowly diluted 1:1 (
v/v) and washed with Ham's F-10 media containing 3% (w/v) BSA. The HOS
test was performed by adding 0.1 ml of the sperm specimen to 1.0 ml o
f a 100 mOsm/L HOS diluent. The following treatments were performed: 1
) Aliquot 1 (control), specimens were incubated in HOS solutions at 37
degrees C for 5 min; 2) Aliquot 2, specimens were incubated in HOS so
lutions at 21 or 37 degrees C for 5 min; and 3) Aliquot 3, specimens w
ere incubated in HOS solutions at 5 or 37 degrees C for 5 min. Samples
were obtained from the sperm specimen-HOS diluent mixtures at 1 min i
ntervals (during the 5 min incubation period), fixed and assessed for
sperm swelling patterns. The sperm response to the HOS test for specim
ens processed at temperatures below 37 degrees C was higher when sampl
es were incubated in HOS diluents at 37 degrees C. This finding indica
tes that the potential for sperm swelling (measurement of sperm membra
ne functional status) can be maintained when spermatozoa are processed
at temperatures below 37 degrees C. The highest response to the HOS t
est was observed in spermatozoa processed at 21 degrees C and incubate
d in a HOS solution at 37 degrees C. The response to the HOS test was
superior to the one observed in specimens maintained and processed at
37 degrees C throughout. Thawing of spermatozoa at 37 degrees C, follo
wed by processing at 21 degrees C seems to reduce the negative effects
associated with osmotic shock and results in the preservation of the
sperm membrane functional status during the in vitro handling of froze
n-thawed bovine spermatozoa. (C) 1997 by Elsevier Science Inc.