The responses of cane toad (Bufo marinus) gametes, used as a model for the
development of assisted reproduction techniques for rave and endangered amp
hibians, to short-term storage at temperatures > 0 degreesC were studied. W
hole excised testes were stored at 0 degrees or 4 degreesC for 15 days, and
sperm motility was measured at excision and after storage for 2, 5, 7, 10,
12 and 15 days. Spermatozoa showed > 50% motility for 7 days at 0 degreesC
and for 5 days at 4 degreesC. At 15 days, only spermatozoa stored at 0 deg
reesC still showed some motility (3%). Sperm suspensions were prepared at 5
day intervals over 96 days in simplified amphibian ringer (SAR) at dilutio
ns of 1:1, 1:5 and 2:20 (w/v) testes:SAR. Aliquots from each dilution were
stored at 0 degreesC in Eppendorf tubes opened at 5 day intervals of storag
e (aerated) or kept sealed (unaerated) (treatments: aerated or unaerated; 5
, 10, 15, 20, 25 and 30 days storage). After 30 days, sperm motility and fe
rtilizing capacity were determined. The optimal protocol for sperm storage
up to 10 days, as assessed by the retention of fertilizing capacity, was as
a 1:5 testis:SAR (w/v) suspension, whereas the longest absolute retention
of both motility and fertilizing capacity was observed in concentrated (1:1
dilution), anaerobic suspensions (up to 25-30 days). Oviductal oocytes pla
ced in SAR at 5, 10, 15, 20 and 25 degreesC immediately after ovulation los
t viability when cooled rapidly to 5 degreesC and stored for 2 h. However,
oocytes retained viability for up to 8 h at the optimum storage temperature
of 15 degreesC. Thus, it is concluded that during short-term storage sperm
atozoa retain viability for longer than oocytes, and that spermatozoa in su
spensions retain viability for longer than spermatozoa stored in situ in ex
cised testes.