Testosterone secretion, testicular histology and the cryopreservation of cauda epididymidal spermatozoa in the common ringtail possum (Pseudocheirus peregrinus)
D. J. Phillips A B , A. McKinnon B , T. Keeley C and S. D. Johnston A DA School of Animal Studies, The University of Queensland, Gatton, QLD 4343, Australia.
B Queensland Parks and Wildlife Service, Environmental Protection Agency, Moggill, QLD 4070, Australia.
C Western Plains Zoo, Dubbo, NSW 2830, Australia.
D Corresponding author. Email: s.johnston1@uq.edu.au
Reproduction, Fertility and Development 20(3) 391-401 https://doi.org/10.1071/RD07206
Submitted: 12 November 2007 Accepted: 13 December 2007 Published: 8 February 2008
Abstract
The present study reports novel aspects of the reproductive biology of the male common ringtail possum (Pseudocheirus peregrinus). Plasma testosterone was measured through a stimulation test using the gonadotrophin-releasing hormone agonist, buserelin. Following intra-muscular administration of buserelin, there was an increase (P < 0.05) in testosterone concentration in the peripheral circulation 4 h later. Quantitative testicular histology of this species was described for the first time. Eight stages of the seminiferous epithelium cycle were identified in 10 possums and their relative frequency determined. Spermatozoa were recovered from the cauda epididymides of hemi-castrated possums and cryopreservation conducted in straws (6°C min–1) using final glycerol concentrations ranging between 2 and 20% in Tris-citrate egg yolk extender (v/v). Frozen straws were thawed and post-thaw motility, rate of motility, the percentage of live–dead spermatozoa and the percentage of sperm with swollen decondensed nuclei recorded. Similar to other marsupial sperm, common ringtail possum cauda epididymidal spermatozoa required high levels of glycerol (10–16%) in order to maintain post-thaw viability.
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