Sperm morphology is an useful characteristic for estimating potential fertility. Currently, we are obtaining baseline information on various aspects of reproduction in the brown bear (Ursus arctos) with the intention of using the knowledge to establish a germplasm bank for the species. In the present report, we describe the results obtained using assisted sperm morphology analysis (ASMA, Sperm Class Analyzer^®; Microptic S.L, Barcelona, Spain) to analyze the morphological differences in epidydimal (caput, corpus, and cauda) and ejaculated brown bear spermatozoa. A post-mortem epididymal sperm sample was obtained from an adult brown bear after accidental death. The epididymides were excised, washed, and dissected into the three major segments; caput, corpus and cauda. Then multiple incisions were made in the tissue to allow migration of spermatozoa into the surrounding medium. Semen was collected by electroejaculation from five adult brown bears living in a semi-free ranging environment in the Cabarceno Park (Cantabria, Spain). Anesthesia was induced using tiletamine + zolazepan (Zoletil 100^®; Virbac, Carras, France; 7 mg/kg), and ketamine (Imalgene 1000^®; Rhone Merieux, Lyon, France; 2 mg/kg). The electroejaculation unit (PT Electronics^®; Boring, Oregon) was connected to a 3-lateral electrode transrectal probe (26 mm in diameter, 320 mm in length). Ejaculation occurred at 6–10 V/250–300 mA. For head morphometry assessment, sperm samples were fixed in glutaraldehyde and slides were smeared and air-dried for 2 h. The samples were then stained with Diff-Quik^® staining (37°C; 10 min in the red component and 15 min in the blue component). The area, perimeter, length and width, and ellipticity (length/width) of heads were measured from at least 100 spermatozoa/slide. As shown in Table 1, values obtained for each measure were similar in both epididymal and ejaculated spermatozoa. These results provide normal morphometry values for brown bear spermatozoa, a potentially useful characteristic for predicting fertility.

This work was supported in part by CANTUR S.A. and CICYT (CGL 2004–0278/BOS).