SPERMIOGENESIS IN RATITES AS A PHYLOGENETIC CHARACTER

摘要

Despite the application of various techniques and the acquisition of volumes of morphological and molecular data, the phylogenetic relationships within the class Aves, and between birds and reptiles, remains a controversial topic. Recently, the value of so-called non-traditional characters such as sperm ultrastructure and morphological aspects of spermiogenesis have been proposed as additional methods of indicating phylogenetic relationships. Although spermiogenesis has been described in many bird species, no morphological characters reflected during this process have been used as phylogenetic data. This study describes the presence of a transient structure that manifests during spermiogenesis in the emu, ostrich and rhea and which may have value as a non-traditional phylogenetic character. Testes samples were collected during mid-breeding season from 10 sexually mature emus (Dromaius novaehollandiae) and ostriches (Struthio camelus), respectively, following slaughter at commercial abattoirs. Small tissue blocks were immediately fixed in 4% phosphate-buffered glutaraldehyde and routinely processed for transmission electron microscopy. Resin embedded testicular samples of the greater rhea, (Rhea americana albisceus) were kindly provided by Dr D.M. Phillips (Rockefellar University, New York).