A REVIEW OF THE METHODS USED TO STUDY THE ANATOMY OF AVIAN SPERM STORAGE

We describe and evaluate a simple technique for studying the anatomy o f sperm storage in birds by using whole mount preparations of unstaine d oviductal tissue. Unlike sectioned material, this technique can be u sed to estimate the number and size of sperm storage tubules (SST) and study the arrangement of stored sperm in situ. Using whole mount prep arations, we compared fresh material with that fixed and preserved in either formalin or alcohol for up to 6 months. SSTs and their contents were easily counted and measured using either fresh or formalin prese rved material; however, material fixed in formalin shrunk by approxima tely 12% and size measurements must be corrected if direct comparisons with fresh material are to be made. Tissue fixed in alcohol gave poor visibility and should not be used to preserve specimens. The use of w hole mount preparations provides new possibilities for addressing both the evolution of different sperm storage patterns across species and the proximate mechanisms of sperm competition within a species. We rec ommend that systematic efforts be made to include formalin fixed and p reserved oviducts in museum collections.