1062-3604/01/3202- $25.00 © 2001
Russian Journal of Developmental Biology, Vol. 32, No. 2, 2001, pp. 119–123. Translated from Ontogenez, Vol. 32, No. 2, 2001, pp. 148–153.
Original Russian Text Copyright © 2001 by Kreshchenko, Sheiman, Fesenko.
Recently, there has been an increased interest in the
biological effects induced by weak electromagnetic
ﬁeld (WEMF), particularly in connection with their
clinical implications. The purpose of this study was to
examine the effect of WEMF on regeneration. Planari-
ans provide the most suitable system for this purpose.
These animals have extreme morphogenetic plasticity.
It was demonstrated in a previous study that WEMF
leads to a slowing down of the regeneration of the ante-
rior end of the planarian body after its amputation (Jen-
, 1995). At about the same time, an opposite
effect was found in another study: regeneration in pla-
narians was stimulated by exposure to WEMF (Tiras
, 1996). In studies on the effect of WEMF on
asexual reproduction or division of planarians (the lat-
ter effect is also associated with morphogenesis),
WEMF altered the kinetic aspects of planarian division.
The effect of WEMF was variable and depended on the
season: stimulation of division was seen during the
spring and summer months; there were ﬂuctuating
effects in the autumn and inhibition during winter, fol-
lowed by a new period of oscillations and indetermi-
nate response (Sheiman and Fesenko, 1999).
Regeneration of the pharynx in planarians after its
amputation is a well-known model of planarian mor-
phogenesis (Kreshchenko, 1993). In the present study,
we present the results of the action of WEMF on phar-
ynx regeneration in planarians.
MATERIALS AND METHOD
, of the asexual labora-
tory race were used. The animals were maintained in
large glass vessels in the shade at 19–22
C. The planar-
ians were fed bloodworms or rainworms twice a week.
Before the experiment, the planarians were not fed for
a week. Animals with similar lengths (9–11 mm) were
used in the experiments. They were placed in 250-ml
glass beakers ﬁlled with tap and water mixed with dis-
tilled water in the ratio 2 : 1. Their pharynges were
removed by the technique described previously (Kresh-
chenko, 1993). Experimental planarians were subjected
to WEMF. Throughout the experiment, planarians were
kept in water, where they were irradiated. WEMF was
obtained from a KSVN R2-65 generator with a sweeping
frequency. Irradiation was conducted at a distance of
30 cm from the source and at the frequency of 36 GHz.
The operation of pharynx amputation was con-
ducted using a ﬁne ophthalmological knife under a bin-
ocular microscope. The planarians were immobilized
with ice. The rate of regeneration was determined by
the restoration of the new pharynx function, i.e., the
appearance of the food reaction in regenerating planar-
ians (Kreshchenko, 1993). Everyday, we determined
the number of specimens with a functional pharynx and
their percentage relative to the total number of animals
in the group. In addition, for each day of regeneration,
we determined the total number of specimens with a
functional pharynx. This index was used for statistical
treatment of the data. Statistical treatment was con-
ducted using the
method for alternative distributions.
A total of 20 experimental series were conducted,
among these were 20 control and 36 experimental
groups. The number of planarians in each group varied
from 30 to 50. The total number of animals was 2966.
The experiments were conducted during the period
from November 13, 1995 to November 14, 1996. Sev-
eral experimental protocols were used, in which we
varied the intensity, duration, and time of exposure to
Studies on the Effect of a Weak Electromagnetic Field
on Pharynx Regeneration in
N. D. Kreshchenko, I. M. Sheiman, and E. E. Fesenko
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow oblast, 142292 Russia
Received November 26, 1999; in ﬁnal form, January 18, 2000
—We have studied the effect of a weak electromagnetic ﬁeld on the morphogenesis of the planarian
. The regeneration of the pharynx was examined after its amputation. We have determined the
rate of the appearance of the food response of a new pharynx. Experimental conditions were varied, such as
dose and duration of irradiation, season, and time of irradiation after surgery. The results of experiments con-
ducted with 2966 planarians have shown that weak electromagnetic ﬁeld has various effects, which appear
either as stimulation of regeneration or as its inhibition. In some experiments, there was no effect at all. These
differences depend on numerous factors and may be modulated.
: planarians, regeneration, pharynx, electromagnetic ﬁeld.