title: Artificial fertilisation in a terrestrial toadlet (Pseudophryne guentheri): effect of medium osmolality, sperm concentration and gamete storage.
abstract: Anurans exhibit a greater reproductive diversity than any other vertebrate order. However, studies investigating the effects of the external fertilisation environment on fertilisation success are limited to aquatic-breeding species. This study investigated the effects of fertilisation medium osmolality, sperm concentration and short-term oocyte storage on fertilisation success in a terrestrial-breeding anuran, Pseudophryne guentheri. Split-clutch experimental designs were used to determine optimal fertilisation conditions. To determine the effect of short-term sperm storage, sperm viability was assessed using fluorescence microscopy and percentage sperm motility and velocity quantified with a computer-assisted sperm analysis system. Fertilisation success was highest in media ranging in osmolality from 25 mOsm kg⁻¹ to 100 mOsm kg⁻¹, representing a broader range and higher optimal osmolality than previously reported for aquatic breeders. High rates of fertilisation (>75%) were achieved in relatively low sperm concentrations (2.5×10⁴ mL⁻¹). Oocytes stored in isotonic solutions (200 mOsm kg⁻¹) retained fertilisation capacity (32%) after 8h of storage, while sperm suspensions maintained motility (≥26%) for 13 days. Additional studies on terrestrial-breeding anurans will be required to ascertain whether the optimal fertilisation conditions reported reflect adaptations to achieve fertilisation in a terrestrial environment.
authors.affiliation: Institute for Conservation Biology and Environmental Management, School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia. Email:
authors.forename: Aimee J
authors.initials: AJ
authors.lastname: Silla
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000254:growth & development / Q000502:physiology*; D001001:Anura / Q000254:growth & development / Q000502:physiology*; D002470:Cell Survival; D003470:Culture Media / Q000378:metabolism; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary*; D060106:Lakes; D008297:Male; D009865:Oocytes / Q000502:physiology*; D009994:Osmolar Concentration; D012034:Refrigeration / Q000009:adverse effects / Q000662:veterinary; D012662:Semen Preservation / Q000009:adverse effects / Q000662:veterinary; D013076:Sperm Count / Q000662:veterinary; D013081:Sperm Motility; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology*; D014021:Tissue Preservation / Q000662:veterinary*; D014904:Western Australia
chemical_list: D003470:Culture Media