Developmental pattern of enzyme secretion in the embryonic venom glands ofVipera palaestinae (Ophidia, Reptilia)

The relationship between morphogenesis and the appearance of secretory components was studied in the venom glands ofVipera palaestinae embryos. Twenty days after oviposition (hatching after 40 days at 30°C), membrane-bound ribosomes, a well developed Golgi apparatus, and some vesicles are evident in the secretory cells. In 25-day-old embryos venom components were detected with fluorescein-labeled antisera against whole venom or against neurotoxin. At this stage the cells have the characteristic columnar shape and tubular lumina are formed. The activity of three enzymes,l-amino acid oxidase, phosphodiesterase, and benzoyl arginine ethyl esterase, which are found in the venom, was first demonstrated in the gland epithelium at about the 30th day of incubation, when well differentiated cells with a high content of succinate dehydrogenase appear among the secretory epithelium. A steepincrease in specific activity of the three exportable enzymes becomes evident at that stage, with the highest level attained at 39 days after oviposition. Shortly after hatching the venom glands have a pattern similar to that of the adults, with both central and tubular lumina filled with secretion material. The specific activity of the enzymes in the venom at hatching, especially that of benzoyl arginine ethyl esterase, is lower than the average specific activity reported for adult snakes.