Neoplasms
The neoplasms (called also tumours, cancer or carcinogenic formations)
are observed usually in animals, but sometimes are also met in plants.
They became a scourge for the human race. The struggle against them is a
foremost task of science and medical practice. For that reason the methods
and remedies for their treatment are permanently improved. Such type of
cells is HeLa-line (Fig. 3–29).
image
Figure 3–29. Scanning electron micrograph of malignant HeLa-cells (Courtesy of K. Porter; From Fawcett, 1981).
An essential peculiarity of neoplasmic cells is their capability to divide
continiously (non-stop) without “obeying” the mechanisms of division
acquired in the process of cell differentiation, which are characteristic of the
other cells forming the different tissues and organs of a certain organism. In
this way conflicting interrelations arise between them, the effect in most
cases being lethal as a result.
According the prevailing concept, transforming the normal cells into
neoplasm (tumour) cells is a multistage process, which depends on many
factors realizing the interaction between the genome and surroundings.
Concerning this aspect, different opinions and hypotheses are expressed
about the causes for transformation resulting in neoplasmic formations.
They can be reduced to three main groups.