The structure of the bursa copulatrix in virgin and mated snails, Helisomaduryi (Mollusca): role of acid phosphatase in reproduction

The fine structure of the bursa copulatrix of the virgin snails has been co mpared with that of mated snails. One of the noticeable changes after matin g is an increase in the number of the Golgi and the secretory vesicles. Sin ce some of the vesicles react positively for acid phosphatase it is suggest ed that this enzyme activity increases following mating. The bursa lumen of the virgin snail contains gel-like materials devoid of spermatozoa, howeve r, following mating, the lumen is full of semen containing live spermatozoa and bacteria. The source of bacteria in the lumen is not known. Acid phosp hatase activity is significantly higher in the luminal content of mated sna ils than in the virgin snails. The activity is higher in the lumen than in the epithelial cells, suggesting that the enzyme is secreted into the lumen where it is utilized for extracellular degradation of spermatozoa. Followi ng mating, the spermatozoa are motile in the lumen of the bursa for similar to3-7 d, but become immobile and finally undergo extracellular digestion s o that intact spermatozoa are not recognizable by day 10. The use of castra ted snails in mating experiments suggest that individuals of Helisoma duryi reproduce by cross fertilization and that the bursa may act as the holding organ from where the spermatozoa are periodically transported to the carre four over similar to7 d. At day 10 following mating, however, autosperms ap pear in the hermaphroditic duct awaiting the next mating.