The secretion of extracellular phospholipases by C. albicans was first reported in the 1960s by Costa et al. (A. Costa, A. Misefari, and A. Amaro, Abstr. Atti XIV Congr. Naz. Microbiol. Messina, abstr. P35 and P36 1967) and Werner by growing the yeast on solid media containing egg yolk or lecithin and analyzing the lipid breakdown products. Later, phospholipase activity was found in many pathogenic C. albicans strains by using media containing blood serum and sheep erythrocytes (30). The observation that C. albicans secretes phospholipase prompted Pugh and Cawson (150) to develop a lecithin-based cytochemical method to detect this enzyme. In a subsequent study, these authors used this method (149) in conjunction with a chicken chorioallantoic membrane model to evaluate ultrastructural details of candidal invasion and to determine the site of phospholipase production. Invasion was initiated by placing stationary-phase blastospores of C. albicans on the membrane, which stimulated cellular changes in the blastospores. Many of the blastospores developed hyphae with phospholipase activity concentrated at the growing tip. The activity was highest where the hyphae were in direct contact with the membrane (149). In general, only hyphae invaded the membrane successfully. Based on these results, the investigators proposed that extracellular phospholipases were important in the invasion of tissue by C. albicans.