The effect of temperature on spontaneous, and ovulation hormone-induced female reproduction in Lymnaea stagnalis.

Spontaneous oviposition of the freshwater pulmonate snail Lymnaea stagnalis stopped after transfer from 20 degrees to low temperatures (8 and 4 degrees). This was due to a reduction in the activities of the neurosecretory caudodorsal cells (CDC), which produce the ovulation hormone (CDCH). Oviposition latencies (time interval between CDCH-injection and start of oviposition) increased with decreasing temperature. The ovotestis and the female accessory sex organs of snails placed at 8 degrees became less sensitive, and those at 4 degrees became completely insensitive to injected CDCH. This was probably caused by a reduction in activities of the endocrine dorsal bodies (DB), which control vitellogenesis and the activities of the female accessory sex organs. After a change from 4 to 20 degrees, CDCH injections rapidly became effective in inducing egg mass production, and spontaneous oviposition also restarted quickly, suggesting a rapid increase in DB and CDC activities.