Microcomputer‐assisted morphometric analysis of airsacculitis caused byMycoplasma gallisepticumin immunised and nonimmunised chickens1

Abstract

Inflammation caused by inoculation of Mycoplasma gallisepticum (MG) into the air sacs was compared in chickens previously exposed by intramuscular injection of MG with that produced in nonimmunised chickens. Air sacs from chickens inoculated with Frey's media, from those receiving only intramuscular injections of MG, and from nonimmunised non‐challenged birds were included in the evaluations. The airsacculitis produced in immunised chickens was more severe at 48 hours post‐challenge infection than that produced in nonimmune chickens. At 96 hours after challenge, the airsacculitis in nonimmunised chickens was significantly more severe than that produced in chickens of any other experimental group. The protective effect of immunisation at 96 hours was demonstrated clearly by using the techniques of ring‐stabilisation for collection, processing, and embedding of air sacs and microcomputer‐assisted morpho‐metric analysis. Air sac wall thickness and area measurements correlated positively with subjective impressions on the degree of airsacculitis and with determinations made by point count analysis of the relative percentage of selected components of inflammation.