The spread of tumors in nature

Tumors are described not only in animals of all classes and types, but also in plants. Tumor plants are fundamentally different from the true neoplasm of humans and animals. Due to the lack of plants mesenchyme they respond to all bitterness growth parenchyma, which can create a picture resembling O. animals, but differ in their biological entity.
A number of authors have studied the embryonic forms of some insects (butterfly Pygaera nigra and the fruit fly Drosophila melanogaster) a kind of tissue growth, which many consider Acting Occasionally Acting Drosophila arise spontaneously and are inherited. They can also be caused by x-rays.
Fish true tumors are found in many collections, appears to be more in bony. Among connective tissue tumors are described as benign O. (fibroma, lipoma, myxoma, chondroma, osteoma)and sarcoma. A special group of tumors in fish are chromatophorum of different histogenesis and different colors. Relatively much research has been devoted to adenomas and adenocarcinomas of the thyroid gland in trout, "pandemicheskim" occurring in certain waters.
In some species of amphibians and reptiles are also found About. So, A. A. Krentowski studied malignant chromatophorum the axolotl. Special attention was paid to tumors of the kidneys in leopard frogs; these are Acting virus because of the presence in their cells inclusions, reminiscent of elementary bullock; filtrates these tumors are not passed.
In birds studied many forms of O. Most often Acting observed in chickens (about 4% of autopsies). A significant part, epithelial O. Kur is localized in the ovaries. Describes many sarcomas different morphological structure. Some sarcoma,built of macrophages, fibroblasts and undergoing lot of mucus, have the ability to perebivaetsya filtrates [Raus (P. Rous)]. These O. called viral sarcomas. They were found in different countries, including the USSR. Frequency Acting in different species of birds are different.
The most extensive and accurate information about tumors based on the study of the huge material on the Acting person and some mammals. Best studied Acting laboratory animals: dogs, cats, and especially mice and rats (Fig. 1). In all species of mammals, including monkeys (Fig. 2), there are both benign and malignant tumors, their number is growing with age and quickens to the end of life. By its morphological structure of the same name O. very similar in different animals, but there are also important differences. Stomach cancer frequency is the person in the first place, but in animals it occurs extremely seldom. Some mammals, such as Guinea pigs, O. occur spontaneously much less often than other rodents, and much more difficult to cause experimentally. Different animals are more common particular type O. Finally, the Acting person, especially epithelial, as a rule, more malignant than Acting animals. Maybe this explains the fact that animals have a multiplicity of different Acting is more common than in person.
Spontaneous tumors animals are widely used for experimental development problems O.

Fig. 1. Spontaneous tumor of the breast mouse. Milkalliance glandular structure.
Fig. 2. Spontaneous tumor of the breast monkeys. Krupnolistnoi glandular structure.