An investigation into the similarities and differences governing the cryopreservation success of koala (Phascolarctos cinereus: goldfuss) and common wombat (Vombatus ursinus: shaw) spermatozoa
Johnston, SD, MacCalum, C, Blyde, D, McClean, R, Lisle, A & Holt, WV 2006, Cryobiology, vol. 53, no. 1, pp. 218-228.
Cryopreservation of spermatozoa is far less successful for koala sperm compared to the sperm of the closely-related common wombat. After thawing, the survival of spermatozoa was greatest when samples were frozen slowly in a 14% glycerol solution. Koala sperm also has low osmotic tolerance compared to that of the wombat. The authors aimed to determine the factors responsible for these differences in post-thaw survival in the two marsupials and predicted that the presence of the microfilamentous protein F-actin in koala spermatozoa might cause inflexibility in the sperm plasma membrane. As F-actin was not detected, however, it is suggested that some other factor may be responsible for the low success rates of koala sperm cryopreservation.