Structure and organization of the spermatozoa within the spermatheca of honey bee queens Apis mellifera intermissa L.

Sperm storage in queen honey bees (Apis mellifera L.) is a determinant phase of reproduction; the spermatheca provides all the requirements needed to keep sperm alive over the years. In the last few decades, several biochemical factors have been shown to be involved in their long-term preservation, with factors related to the male and others related to the queen. However, little is known about the relation between spermatozoa–spermatheca structures and particularly, whether this long term conservation involves an intimate adhesion between gametes and spermatheca epithelium. In addition, no previous research has reported the general organization of bee spermatozoa inside the spermatheca. The aim of the present study was particularly the exploration of the disposition of sperm cells inside the spermatheca of a fertilized queen using scanning electronic microscopy. The results showed that spermatozoa cells occupy the total volume of the spermatheca reservoir, with gametes in contact with the epithelium and others in the center of the lumen. It seems that no intimate relationship is required between gametes and spermatheca epithelium to provide the long lifetime of spermatozoa. The sperm cells seem to adopt different shapes according to the spermatheca regions; coiled shaped spermatozoa were observed in the periphery and uncoiled shaped ones were present in the center of the lumen.