Experimental study of tumors

The role of animal parasites in the occurrence of tumors. Some clinical observations forced to search for the link between the occurrence of tumors and presence in the tissues of humans and animals some parasites. This includes cancer of the bladder, a frequently observed in the SAR with the defeat of bilharzia (see Schistosomiasis). There are a number of details about the comparative frequency of cancer of the liver and biliary tract people affected by opisthorchiasis (see). Known and experimental observations are some authors who believe that parasites can cause the development O.
The role of viruses in the development of tumours. Established by Rous transfer some sarcomas chickens material which does not contain cells, initiated the study of the so-called viral O. (see Opujolevidnami viruses).
In the filtrate sarcoma chickens found a kind of Taurus (the virus rous)whose properties have been extensively studied.
The introduction of the filtrate rous sarcoma in a cloth (if perebivki on hens) first cause an inflammatory reaction and formation of granulation tissue, cellular elements which influenced entered filtrate very quickly, within a few days, malignities. Malignant transformation is the result of direct exposure of normal tissues with the applicable agent filterable sarcoma. Intrusion normal chickens from chickens with filterable sarcoma is not observed, even if they are in the same room and in close contact.
Shop (R. E. Shope) described a kind-borne effluents papilloma in wild rabbits in the USA. The filtrate papillomas such deposited on skalpirovaniya skin standard laboratory rabbits, causes them after a few weeks, the same tags. After a few months (usually a year) papilloma become squamous cell orogovevshi cancer, later giving metastases and lead animals to death. In tissue cancers arising from papillomas, the operating agent discover no longer possible. Attempts to malignizaciei using agent Sopa tissue culture or grafts normal epithelium failed.
Bittner (J. J. Bittner) found that in the milk of female mice of vysokorakovyh line is the factor causing breast cancer in mice. He was found not only milk, but also in breast tissue, arising from their tumors in various organs of mice, in particular in the spleen and blood. Introduction with the material of these organs and tissues in the peritoneal cavity or under the skin of the newborn mice nizoraluau line aged 9-14 days causes them through 5-6 months. multiple adenomatous nodules in the mammary glands, which are precancerous changes. One of them even a few months there is initially more or less benign, and then explicitly malignant O. breast - adenoma and adenocarcinoma, sometimes cystadenocarcinoma that in some cases metastasize; these tumors successfully perebivaetsya on animals the same line.
Although for several of its properties factor milk close to viral agents, its effects, and may be the origin, closely connected with the peculiarities of organism and tissues and are determined by them. Thus, the factor of milk only discovered in mice certain lines, genetically different from the others. In mice other lines that do not have a factor of milk, you can call (for example, carcinogenic substances) cancer of the mammary glands, in which the factor of milk there. In mice, males vysokoprochnykh lines there is the factor of milk, but breast cancer does not occur. Just enter such males estrogen hormonebreast to get their cancer. On the other hand, using estrogen can cause breast cancer in animals, which have no factor of milk, for example in rats, both females and males. In other words, the factor of milk without estrogen cancer does not cause, estrogens without this factor can cause cancer.
Factor milk found only in mice vysokoprochnykh lines, other animals and humans it is not observed.
Describes the three opujolevidnami virus (sarcoma chickens, papilloma rabbits and breast cancer mice) have a number of differences, but one very significant similarities - they all strictly specific, i.e. each of them is of only one specific type of tumor. There is also information about opujolevidnami the viruses that cause various Acting in different animals, which they entered. In such cases they say about the virus "polyoma" (in other words, polypectomy), i.e. about the virus that causes different tumors. This same property can have and other viruses, such as the SV-40 and some viruses leukemia.