Maternal impact on egg development in Lymnaea stagnalis: a growth factor is produced by the albumen gland in the reproductive tract

In the freshwater snail Lymnaea stagnalis, perivitellin fluid is the main s ource of nutrition for developing embryos; it contains predominantly galact ogen and proteins. The fluid is produced by the albumen gland, a large exoc rine organ in the female reproductive tract. To further define the protein products of this gland and provide more information about the maternal cont ribution to egg development, albumen glands were extracted and the extracts purified by reversed-phase HPLC. One major HPLC peak fraction exhibited ne urotrophic activity when bioassayed on identified Lymnaea neurons in vitro; it has been partially sequenced and has the highest degree of sequence ide ntity with epidermal growth factor (EGF). These results demonstrate that a growth factor with neurotrophic activity is produced by the albumen gland, and is packaged along with the eggs to serve a growth-promoting function in the embryo.