ISSN 1062-3604, Russian Journal of Developmental Biology, 2006, Vol. 37, No. 1, pp. 22–26. © Pleiades Publishing, Inc., 2006.
Original Russian Text © I.M. Sheiman, Z.V. Sedel’nikov, N.D. Kreshchenko, 2006, published in Ontogenez, 2006, Vol. 37, No. 1, pp. 27–31.
In the course of regeneration of planarians after their
damage (amputation of head end or pharynx), the dis-
turbed functions are restored, as a rule, within ﬁve to
seven days. By this time, after amputation of the ante-
rior body end, the head ganglion begins to function and,
after amputation of the pharynx, the feeding reactions
reappears (Sheiman, 1984; Kreshchenko, 1993). How-
ever, restoration of the initial size of a regenerating
body part requires much longer time: about four weeks.
Thus, the growth of a regenerate is characterized by two
stages: the ﬁrst of them, initial, appears to be the key
stage, since it is related to the restoration of the func-
It was shown that at the initial stage of regeneration
of a lost body part, the growth of blastema depended on
the position of the wound and on the polarity of regen-
eration process (Sheiman
This communication deals with analysis of the
blastema growth at the ﬁrst stage of regeneration as a
function of distribution of cellular sources of regenera-
tion: totipotent cells—neoblasts. Localization of these
cells in planarians has already been described: accumu-
lation in front of the ganglion and pharynx (Pedersen,
1959) and, in planarians reproducing by asexual way,
also in the ﬁssion zone (Sakharova
, 1974). The
neoblasts located at a distance of about 500
the wound surface divided and migrated towards this
surface at a much higher rate than those from remote
body parts (Salo and Baguna, 1989). However, the neo-
blasts, which do not directly adjoin the wound surface,
also migrated very actively to the wound area after divi-
sion (Newmark and Sanchez-Alvarado, 2000). The
cells in the blastema itself do not divide (Salo and
The aim of this work was to study the blastema
growth as a function of the regenerating fragment size,
number of regeneration foci, and functional restoration
of the regenerate.
MATERIALS AND METHODS
Studies were carried out on an asexual race of
Girardi (Planaria). In order to study mor-
phogenetic differences, planarians were transected at
different body levels and pharynx was amputated.
Experiments were also carried out on body fragments
after their ﬁssion (asexual reproduction), which
occurred as a result of tissue break at the ﬁssion zone
behind the pharynx.
Planarians were transected in front of or behind the
pharynx (the last transection was located in the zone of
ﬁssion). After each operation, one large fragment
including the pharynx area (Fig. 1a, 1–7, 4–10) and one
small fragment (Fig. 1a, 8–10, 1–3) were obtained.
Fragments 1–7 and 8–10 were obtained as a result of
natural ﬁssion of planarians. Additional transections
were made for separate tasks and the resulting frag-
ments were designated by numerals corresponding to
the scheme. Regeneration blastema was an object of
studies. Each blastema, head (HB) and tail (TB), was
designated by numerals corresponding to arbitrary divi-
sion of the body into fragments. The areas of body and
blastema were measured using the method of computer
morphometry described elsewhere (Sheiman
2004). Measurements of the blastema area were per-
formed in the period from day 3 until day 7 (sometimes
day 10) of regeneration. The area was expressed in arbi-
trary units (1 mm
= 1266 arb. units).
Resources of Regeneration in Planarians
I. M. Sheiman*, Z. V. Sedel’nikov**, and N. D. Kreshchenko*
* Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia
** Pushchino State University, Pushchino, Moscow oblast, 142290 Russia
Received June 30, 2004; in ﬁnal form, February 17, 2005
—We studied the intensity of blastema growth in operated planarians at an early stage of regeneration
as a function of the following factors: area of regenerate and its function and number of regeneration foci (vol-
ume of regeneration). There was no direct dependence between the intensity of regeneration and the size of
regenerating fragment, as well as the volume of regeneration. Some speciﬁc features of the early stage of regen-
eration have been described, which suggest its determinate character. The behavior of neoblasts during forma-
tion of blastemas with different localization is discussed.
: planarians, regeneration, blastema, neoblasts.