Immaturity of the inflammatory response of the chick chorioallantoic membrane.
Previous tests on the chick embryo chorioallantoic membrane (CAM) had shown the 24- to 48-hr response to irritants to be necrosis, with a primitive granulation proliferation at the periphery. There were few heterophils (avian neutrophils). The present investigation confirmed the immaturity of blood leucocyte development. Few heterophils were seen at 14 days but were found in significant numbers on the 19th and 20th days just before hatching. The numbers of blood heterophils in 14-day-old embryos were almost doubled and the number of immature granulocytes slightly reduced when the CAM was treated with zymosan or N-formylmethionyl peptide, which are chemo-attractants for mammalian neutrophils. Treatment with chemicals that do not have selective activity for neutrophils, for example a surfactant or alcohol, did not stimulate this change. It was not feasible to pretreat 14-day-old embryos to increase the number of heterophils or to use 19- to 21-day-old embryos as a model to detect irritants inducing an acute inflammatory response, or to make the CAM more relevant as a substitute for the in vivo eye irritation test. No difference was found in the phagocytic ability of macrophages of 14-day-old embryos and 16-wk-old adults. Macrophages from both sources contained lactate dehydrogenase and beta-glucuronidase revealed by histochemical and fluorometric examination, and non-specific esterase by histochemistry, though staining was stronger in cells from the adults.
Friend
J V
JV
Unilever Research & Engineering, Environmental Safety Laboratory, Colworth House, Sharnbrook, Bedford MK44 1LQ, UK.
Crevel
R W
RW
Williams
T C
TC
Parish
W E
WE