Squids have more than two accessory reproductive glands, namely oviducal and nidamental glands which release gelatinous substances at the time of spawning to produce an egg mass and in some sepiolids and loliginids there also exist accessory nidamental glands (Hamabe, 1962; Boletzky, 1986; Mangold, 1987). An exception are some enoploteuthid squids which lack the nidamental glands but have large oviducal glands (Naef, 1923). Ikeda et al. (1993) showed experimentally that the gelatinous substance from the oviducal gland has the role of generating the elevation of the chorion at fertilization, which causes the formation of the perivitelline space in squid such as Todarodes pacificus; the perivitelline space became larger during embryonic development in the presence of the oviducal gland jelly. Since T. pacificus lacks accessory nidamental glands (Sasaki, 1921), we address the question as to whether the gelatinous substances of nidamental gland origin also induce the formation of perivitelline space, as does the oviducal gland jelly in T. pacificus, based on the observations of artificial insemination.