“…Later, it was also demonstrated that the cells memorize their first encounter with the hormone (hormonal imprinting) and this memory influences their binding capacity and reaction to the hormone, even after hundreds of generations (Csaba, 1980(Csaba, , 1985(Csaba, , 2000. On the basis of these observations, it was also clear that immunologically (and functionally) demonstrable hormones and hormone-like molecules of higher ranking animals such as insulin, ACTH, HCG, relaxin, endothelin, serotonin, histamine, interleukin 6, b-endorphin, and melatonin are present in Tetrahymena Kova´cs, 1999, 2000;K} o ohidai et al, 2000, 2003Lenard, 1992;LeRoith et al, 1980LeRoith et al, , 1982LeRoith et al, , 1983Roth et al, 1982), and that signal transduction systems characteristic of higher vertebrates (enzymes, second messengers) also occur in them (K} o ohidai et al, 1992;Kova´cs and Csaba, 1987, 1990, 1997Kuno et al, 1979).…”