title: Normal sperm morphology and changes of semen characteristics and abnormal morphological spermatozoa among peri-mating seasons in captive japanese black bears (Ursus thibetanus japonicus).
abstract: The objectives of this study were to obtain morphological data for normal spermatozoa and to investigate seasonal changes (the early, mid- and post-mating seasons) in abnormal morphology of spermatozoa and the characteristics of semen in Japanese black bears. Semen was collected by electroejaculation from 34 captive male Japanese black bears a total of 74 times. Length of head, width of head, length of midpiece and total length of the spermatozoa were 6.3 +/- 0.4, 4.5 +/- 0.3, 10.4 +/- 0.7 and 69.6 +/- 3.1 mum (mean +/- SD; 20 semen, 200 spermatozoa), respectively. In the semen collected during the mid-mating season, ejaculate volume, ejaculate pH, sperm concentration, total sperm count, motility, viability and intact acrosomes were 0.46 +/- 0.36 ml, 7.3 +/- 0.4, 659 +/- 644 x 10(6)/ml, 214 +/- 208 x 10(6), 82.9 +/- 9.6%, 89.3 +/- 9.5% and 97.0 +/- 3.2% (mean +/- SD; n=21, in ejaculate pH n=8), respectively. Sperm motility and viability in the early (n=7) and mid-mating (n=21) seasons were significantly higher than in the post-mating (n=8) season. The rates of detached heads in the early and mid-mating season were significantly lower than in the post-mating season. The main abnormal morphologies observed (mean +/- SD%; n=23) were simply bent tail (19.9 +/- 22.6), distal droplets (13.5 +/- 11.7), proximal droplets (9.6 +/- 7.8), teratoid spermatozoa (6.7 +/- 10.7), knobbed acrosome (4.9 +/- 8.6), acrosome damage (3.7 +/- 2.8) and bent midpiece (3.7 +/- 5.1). The data will be useful for artificial breeding and further research on male reproductive physiology in this species.
authors.affiliation: United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Okano
authors.forename: Tetsuma
authors.initials: T
authors.lastname: Murase
authors.forename: Sachiko
authors.initials: S
authors.lastname: Nakamura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Komatsu
authors.forename: Toshio
authors.initials: T
authors.lastname: Tsubota
authors.forename: Makoto
authors.initials: M
authors.lastname: Asano
mesh_terms: D000177:Acrosome / Q000502:physiology; D000818:Animals; D000836:Animals, Zoo / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008297:Male; D008858:Microscopy, Phase-Contrast / Q000662:veterinary; D012621:Seasons; D012661:Semen / Q000502:physiology*; D013076:Sperm Count / Q000662:veterinary; D013077:Sperm Head / Q000502:physiology; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure; D001503:Ursidae / Q000502:physiology*