Paris, D.B.B.P., Paris, M.C.J., Gilmore, D.P., Mackay, S., Ullmann, S.L., Kennedy, M., and Payne, A.P. (2006) Migration efficiency of paired sperm in the tract of the peri-ovulatory female grey short-tailed opossum (Monodelphis domestica). In: [Presented at the International Symposium on Spermatology]. P2-15. p. 80. From: 10th International Symposium on Spermatology, 17-22 September 2006, Madrid, Spain.

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Abstract

American marsupials are the only mammals known to ejaculate paired spermatozoa, which confer a motility advantage in vitro over single spermatozoa in viscous environments. In the only American marsupial examined, the Virginian opossum (Didelphidae), relatively low numbers of spermatozoa are ejaculated (106), but transport is extremely efficient with ~1 in 20 spermatozoa reaching the site of fertilization compared to ~1 in 10,000 in the rabbit. This study examined the post-copulatory distribution and state (paired or single) of spermatozoa at various times in the female reproductive tract of another didelphid, the polyovular grey short-tailed opossum (Monodelphis domestica). After a single mating, the reproductive tracts of 19 females were dissected at 0.5 (n=4), 6 (n=4), 12 (n=3), 18 (n=3) and 24h (n=5) post coitum (p.c.). Each tract was dissected into 8 major anatomical sections and spermatozoa were recovered by flushing. Mating occurred 5.4 ± 0.4d (mean ± SEM; n=19) after pairing, copulation lasted 4.4 ± 0.2 min (n=18) and ovulation occurred 18.0 - 24.1h p.c. (n=5). Shortly after mating (0.5h p.c.) the tract contained 1.2 ± 0.2g of seminal gel (n=2) and 2.0 ± 1.3 x106 spermatozoa (n=3; 38% of which were paired) found predominantly in the anterior vaginal culs de sac. A uterine sperm reservoir was never observed, but spermatozoa reached the isthmus and ampulla within 6 and 18h p.c. respectively. Paired spermatozoa localized almost exclusively in the isthmus from 6h p.c., and pairing decreased to only 4% of the total sperm population in the tract by the start of ovulation. In total ~1 in 300 ejaculated spermatozoa (~6.5 x103; n=9) reached the oviduct. In conclusion, sperm pairing appears to confer effective colonization of the isthmus in M. domestica and, like the Virginian opossum, transport of spermatozoa is relatively efficient.

Item ID:	58240
Item Type:	Conference Item (Abstract / Summary)
Keywords:	sperm cooperation, opossum, marsupial, sperm transport, mating, ovulation,
Funders:	European Commission
Projects and Grants:	Marie Curie Incoming International Fellowship
Date Deposited:	23 Jul 2019 03:00
FoR Codes:	06 BIOLOGICAL SCIENCES > 0608 Zoology > 060803 Animal Developmental and Reproductive Biology @ 60% 06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060303 Biological Adaptation @ 20% 06 BIOLOGICAL SCIENCES > 0608 Zoology > 060807 Animal Structure and Function @ 20%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 70% 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960899 Flora, Fauna and Biodiversity of Environments not elsewhere classified @ 30%
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