Sperm transport in the female reproductive tract of the brushtail possum, Trichosurus vulpecula, following superovulation and artificial insemination

This study investigated sperm transport following superovulation and artifi cial insemination (AI) in the common brushtail possum, Trichosurus vulpecul a. Females were superovulated by treatment with 15 IU pregnant mare serum g onadotrophin (PMSG) then 4 mg luteinizing hormone (LH) 78 h later. Insemina tions were performed 27 h after LH (4 million motile spermatozoa/ uterus). At 1.5, 3, 6, 9 and 12 h after AI (n = 5 per group), females were euthanise d and reproductive tracts removed for examination and flushed for sperm. No ovulations had occurred by 1.5 h, but 20% of animals had ovulated by 3 or 6 h, and 80% by 9 or 12 fi. The mean numbers of spermatozoa recovered range d from 249 to 275 X 10(3) in the uterus; 16-51 X 10(3) in the isthmus; 8-11 X 10(3) in the middle segment; and 6-16 X 10(3) in the ampulla at 1.5, 3 a nd 6 h after Al. Sperm numbers in all regions decreased at later times (P < 0.05) except the isthmus, where 100 X 10(3) sperm were recovered by 12 h, Highly motile thumbtack sperm (a putative indicator of capacitation in mars upials), were recovered from the isthmus (20%), middle segment (50%) and am pulla (90%) at all sampling times, but not from the uterus. The epithelium of the oviduct segments contained mucus-secreting and ciliated cells and pe ak secretory activity was observed in the ampulla at 6 h. At 3, 6 and 12 h, many spermatozoa were found in epithelial folds within the isthmus. The pr esent study has provided basic information on sperm transport and storage e vents within the female reproductive tract of T. vulpecula following supero vulation and AI. It is concluded that this model may be useful to better un derstand pre-fertilization sperm maturation events in the possum, which cou ld facilitate the development of IVF technology. (C) 2000 Elsevier Science B.V. All rights reserved.