Steady direct current (dc) electric fields exist in many biological sy
stems over many hours. At these times cells are dividing, differentiat
ing, moving to final locations and extending motile processes. Each of
these events may be influenced by physiological electric fields in ti
ssue culture and when electric fields are disrupted in vivo, major dev
elopmental abnormalities arise. The likelihood of physiological electr
ic fields playing a role in cell behaviours and some potential mechani
sms are outlined.