Distribution of sperm in the storage organs of the Drosophila melanogaster female at various levels of insemination

Summary

It has been shown in Drosophila melanogaster that when 50 or fewer sperm are stored in the female, some 58% are found in the spermathecae and 42% in the ventral receptacle. When between 51 and 100 are stored, some 34% are found in the spermathecae and 66% in the ventral receptacle. The more commonly encountered distribution of 10–20% in the spermathecae and 80–90% in the ventral receptacle hold for higher levels of insemination (greater than 100 sperm). The reason for the relatively high proportion of sperm stored in the spermathecae when the total number of sperm stored is small is unknown. It is pointed out that in experiments dealing with sperm: progeny ratios, careful counting of sperm in the spermathecae becomes of critical importance, especially at low levels of insemination.