Straight Oso4versusGlutaraldehyde-Oso4In Sequence as Fixatives for the Granular Vesicles in Sympathetic Axons of the Rat Pineal Body

Abstract

Six pineal bodies from male and female adult and 21-day old rats were removed immediately after death cut into 2 or 3 pieces, and subjected to experimental fixations at pH 7.3, 0-4 C as follows: 1-2 hr. in 1% OSO4, with veronal-acetate buffer of phosphate buffer; 3-4 hr. in 3%"or 6% glutaraldehyde in 0.1 [image] or 0.2 [image]phosphate buffer, with or without 1% sucrose. Specimens from OsO4 were dehydrated and embedded in epoxy resin; those from glutaraldehyde were allowed to soak in buffer for 12-16 hr. then transferred to 1% OsO4 at 0-4 C for 2 hr. and embedded in the same manner as the ones fixed directly in OSO4. Representative electron micrographs of postganglionic sympathetic endings were studied for the morphology and frequency of granular vesicles. No consistent difference was shown between vesicles fixed in OsO4 buffered by phosphate or by veronal-acetate, nor was there any effect caused by the different concentrations used for the glutaraldehyde solution; however, vesicles fixed by the glutaraldehyde-OsO4 sequence showed an enhancement in the graniness of their membranes, were slightly larger, and had a much larger dense core than those fixed by OsO4 alone. After glutaraldehyde-OsO4, granular vesicles showed a frequency of 81%, whereas after direct fixation in OsO4, only 40% without significant change their number per unit area. Therefore, glutaraldehyde-OsO4 seems to be more effective than straight OsO4 for the demonstration of granular vesicles in the autonomic nervous system.