title: Spermatozoa morphology during the breeding season in Thoroughbred stallions in Japan.
abstract: The morphology of spermatozoa of modern Thoroughbred stallions in Japan was investigated during the breeding season. A total of 299 semen samples were collected from the penises of 16 stallions immediately after service. The rate of abnormalities in sperm heads and tails, spermatozoa with cytoplasmic droplets and slides with medusa cells to total observed slides in each stallion were 3.9 +/- 2.1%, 11.5 +/- 5.9%, 2.4 +/- 2.6% and 20.1%, respectively. The values for the area, length, width and aspect ratio of the stallion sperm head were 12.54 +/- 1.34 microm(2), 5.93 +/- 0.40 microm, 2.69 +/- 0.21 microm and 0.46 +/- 0.05, respectively. With the exception of medusa cells, the features were significantly different among the stallions (P<0.05).
authors.affiliation: Department of Large Animal Clinical Sciences, Graduate School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Koyago
authors.forename: Ken
authors.initials: K
authors.lastname: Nakada
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tsunoda
authors.forename: Masaharu
authors.initials: M
authors.lastname: Moriyoshi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sawamukai
mesh_terms: D000818:Animals; D001947:Breeding; D006736:Horses / Q000502:physiology*; D008297:Male; D013077:Sperm Head / Q000502:physiology* / Q000648:ultrastructure; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure