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sperm storage in caecilian amphibians蚓螈两栖动物精子存储
Kuehnel and Kupfer Frontiers in Zoology 2012, 9:12 /content/9/1/12 SHORT REPORT Open Access Sperm storage in caecilian amphibians Susanne Kuehnel1 and Alexander Kupfer1,2* Abstract Background: Female sperm storage has evolved independently multiple times among vertebrates to control reproduction in response to the environment. In internally fertilising amphibians, female salamanders store sperm in cloacal spermathecae, whereas among anurans sperm storage in oviducts is known only in tailed frogs. Facilitated through extensive field sampling following historical observations we tested for sperm storing structures in the female urogenital tract of fossorial, tropical caecilian amphibians. Findings: In the oviparous Ichthyophis cf. kohtaoensis, aggregated sperm were present in a distinct region of the posterior oviduct but not in the cloaca in six out of seven vitellogenic females prior to oviposition. Spermatozoa were found most abundantly between the mucosal folds. In relation to the reproductive status decreased amounts of sperm were present in gravid females compared to pre-ovulatory females. Sperm were absent in females past oviposition. Conclusions: Our findings indicate short-term oviductal sperm storage in the oviparous Ichthyophis cf. kohtaoensis. We assume that in female caecilians exhibiting high levels of parental investment sperm storage has evolved in order to optimally coordinate reproductive events and to increase fitness. Keywords: Reproduction, Sperm storage, Amphibians, Caecilians Background sperm storage has also evolved in the third group of ex- Animal reproductive strategies include variable modes of tant amphibians, the limbless caecilians [5,6]. sperm transfer, fertilization, and type of offspring deve
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