Crane Fly Spermatocytes and Spermatids: A System for Studying Cytoskeletal Components

This chapter studies cytoskeletal components of the crane fly spermatocytes and spermatids. Normal living crane fly spermatocytes have been studied using phase-contrast and polarization microscopy. Information has been obtained about chromosomal orientations during various stages of meiosis and about velocities of movements during the different stages of meiosis. The IV-instar larvae are distinguishable from III-instar larvae by the size of the spiracles at the rear end of the larvae. Male larvae cannot be distinguished from female larvae using external markers, however, so it is impossible to choose male larvae with 100% accuracy. It is found that 80% of the males had become IV-instar when only 62% of the total had become IV-instar. It is observed that even if there were no way to distinguish male from female crane fly larvae, one increases one's chances of choosing males by restricting the choice to the first 50–60% of the group to become IV-instar. It is suggested that better synchrony might be obtained by keeping the animals at constant density and at constant humidity in a constant-temperature incubator.