Ageing and reproduction in Cr Uznema Lambdiensis (Nematoda: Rhabditidae)

Abstract

In virgin females of Cruznema lambdiensis the ovary released fewer oocytes than did copulating females. Unfertilized oocytes failed to develop an egg shell and usually ruptured in the uterus. The degraded egg mass passed out of the body during vulval twitchings or was reabsorbed by the uterine wall. In old virgin females, the ovary gradually became vacuolated and then shrivelled up. In copulating females as many as 171 eggs were produced on the first day. Fertilization took place in the spermatheca but the oocytes first encountered the sperm in the oviduct. Eggs were laid in batches but in older females they were retained in the body and ultimately led to 'endotokia matricida'. Spermatozoa in virgin males began maturing by the end of the final moult and within a day filled the entire seminal vesicle. On the third day they began to degenerate. Degenerate spermatozoa had either a condensed cytoplasm or their outer layer became mammillated. The testis degenerated in the same way as the ovary. Normally copulating males did not accumulate sperm in their seminal vesicles. The mean life span of virgin worms was 10 days and that of non-virgins 6.5 days. When ageing males were mated with young virgin females or vice-versa, egg production gradually decreased.