CAM assay
As a CAM ( c horio- a llantoic m embrane) assay , a method is known with which (using fertilized and incubated avian eggs embryonated chicken eggs investigations are carried out). To do this, the CAM (a membrane formed from chorion and allantois ) is exposed and thus made accessible for experiments and observations.
For example, tumor cells (but also any type of body) can be applied to the membrane that forms and their behavior can be observed. Since the blood vessels of the CAM are visible, cells and other substances can also be injected into them. After completion of the experiment, the CAM and the liver of the embryos can be prepared with little effort and examined microscopically in sections after fixation and staining.
The technology makes it possible, within the development time of the embryos of one to two weeks, to make statements about the effects of the tumor cells on the CAM, such as their survival, their invasiveness (in CAM and blood vessels) and metastasis (e.g. in the liver) at the same time. The tumor cells are accessible for experiments in the cell culture.
Since an immune system only develops after about two weeks, there are no influences of the immune defense on the system.
Originally, chicken and turkey eggs have been used in biology for decades due to their relatively easy accessibility and low procurement price compared to breeding animals (such as mice and rats).
The experiments can also be carried out without conflicting with the Animal Welfare Act and by any experimenter, as they do not constitute animal experiments in the legal sense . Since the CAM is not innervated, it can be assumed that the embryo does not experience any pain sensations, which frees the experimenter from burdening his conscience. However, the embryos respond with movements to light stimuli that occur during the experiments.
A disadvantage of the method can be seen that the examinations cannot be compared directly with human patients (and test animals), since the latter have an immune system. This must be included in the considerations depending on the question.
Individual evidence
- ^ R. Schneider, et al .: Forskolin-induced differentiation of BeWo cells stimulates increased tumor growth in the chorioallantoic membrane (CAM) of the turkey (Meleagris gallopavo) egg. In: Annals of Anatomy - Anatomischer Anzeiger . Volume 193, Number 3, May 2011, pp. 220-223, ISSN 1618-0402 . doi : 10.1016 / j.aanat.2011.02.007 . PMID 21440429 .
- ↑ I. Grinberg, et al .: Engraftment of human blood malignancies to the turkey embryo: a robust new in vivo model. In: Leukemia Research . Volume 33, Number 10, October 2009, pp. 1417-1426, ISSN 1873-5835 . doi : 10.1016 / j.leukres.2009.02.009 . PMID 19297019 .