ISSN 1062-3604, Russian Journal of Developmental Biology, 2009, Vol. 40, No. 5, pp. 255–263. © Pleiades Publishing, Inc., 2009.
Original Russian Text © V.Ya. Brodsky, 2009, published in Ontogenez, 2009, Vol. 40, No. 5, pp. 323–333.
In the late 1830s, Matthias Schleiden and Theodor
Schwann generalized the microscopy ﬁndings of the 18th
and early 19th centuries and proposed the cellular structure
of plants and animals. Thirty years later, Rudolf Virchow
(1859) substantially developed this fundamental concept.
His book and subsequent works of many researchers have
established the bases of the cell theory: cells are formed
only from other cell; cell is a fundamental unit of the organ-
ism structure and function; and the organism is a totality of
cells. In the ﬁrst half of the 20th century, the cell theory has
become a biological axiom. No cases when a cell origi-
nated not from another cell were reported. Plant and animal
organisms are formed from a single cell, zygote. Histogen-
esis is based on differentiation of individual cells. Some
differentiated cells can divide; in this case, they separate
from the environment and demonstrate an individual pat-
tern. Cells can be isolated, and they can live and divide in a
nutrient medium for some time. Under particular condi-
tions, an entire plant can grow from a single somatic cell.
Thus, the cell theory gets an increasing support con-
cerning cell reproducibility in a series of generations. Two
other dogmata of the cell theory were questioned: the cell
as a structural and functional unit of the organism and the
organism is a simple totality of cells. The doubts were cast
by current data on direct cell–cell communications. Struc-
tural links between plant cells have been found. Permanent
contacts have been found in animal cell layers permeable
for ions and small molecules migrating from cell to cell.
Current morphological and physiological studies consider
the organism as a complex of supracellular ensembles with
internal relationships and, in animals, regulated by the cen-
tral nervous signals rather than as a totality of cells. Revis-
iting the cell theory was proposed (Balu ka et al., 2006).
While disagreeing with this extreme view, I will mention
experimental data reﬁning and developing the cell theory.
Cytoplasmic bridges between cells were described in
primitive multicellular organisms Volvocales (reviewed in
Hoops et al., 2006). The bridges contain contractile pro-
teins. The system of bridges deﬁnes the volvox shape.
Bridge contractions favor the transport of nutrients and
some other structures from cell to cell. An analogy between
cytoplasmic bridges in Volvocales and plasmodesmata in
plants is discussed (Heinlein and Epel, 2004). Another
primitive multicellular organism
only three cell layers. The middle ﬁbrillar cells form the
syncytium with processes connecting it to cells of the dor-
sal and ventral epithelium, and actin functions as the key
morphogenetic component of middle cells (Seravin and
The data on the
and volvox structure do not
contradict the cell theory fundamentals but rather demon-
strate one of possible functional regulations mediated by
direct cell–cell communications.
Plasmodesmata integrating plant cells into a structural
and functional community is a ﬁne example of cell–cell
communications (Gamalei, 1997; Wu et al., 2003; Heinlein
and Epel, 2004; Cilia and Jackson, 2004; Gillespie and
Oparka, 2005; Kim et al., 2005). Plasmodesmata allow
The Cell Theory. Progress in Studies
on Cell–Cell Communications
V. Ya. Brodsky
Kol’tsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, Moscow, 119334 Russia
Received November 10, 2008; in ﬁnal form, February 12, 2009
Abstract—Current data conﬁrm the fundamental statement of the cell theory concerning the cell reproduction
in a series of generations (omnis cellula e cellula). Cell communities or ensembles integrated by the signaling
systems established in prokaryotes and protists and functioning in multicellular organisms including mammals
are considered as the structural and functional unit of a multicellular organism. The cell is an elementary unit
of life and basis of organism development and functioning. At the same time, the adult organism is not just a
totality of cells. Multinucleated cells in some tissues, syncytial structure, and structural–functional units of
organs are adaptations for optimal functioning of the multicellular organism and manifestations of cell–cell
communications in development and deﬁnitive functioning. The cell theory was supplemented and developed
by studies on cell–cell communications; however, these studies do not question the main generalizations of the
: cell, cell theory, cell–cell communications, structural–functional units of organs, cell contacts, plas-
modesmata, nanochannels, neurotransmitters.