A developmental study of the localization of NADPH-diaphorase in the ganglionated plexus of the guinea-pig gallbladder

A histochemical investigation of age-related changes that occur with respect to the localization of NADPH-diaphorase in the ganglionated plexus of the guinea-pig gallbladder was carried out. In all age groups examined (embryonic stages day 34 and 52, 2 to 4-day old, 6-month old and 2-year old), the mean percentage of NADPH-diaphorase-positive neurons per ganglion was obtained by taking the number of neurons that were immunoreactive to protein gene product 9.5 (a general neuronal marker) as 100%. In addition, the possible co-existence of NADPH-diaphorase and nitric oxide synthase in the ganglionated plexus of 2 to 4-day old and 6-month old guinea-pig gallbladder was investigated. NADPH-diaphorase was not present in the ganglionated plexus of the gallbladder at embryonic day 34. At embryonic day 52, all the protein gene product 9.5-immunoreactive neurons showed positive staining to NADPH-diaphorase; this dropped to a minimum at 2–4 days (26.7%), rose slightly at 6 months (33.6%), and finally returned close to the 100% value at 2 years. In the gallbladders of 2-year old guinea-pigs, some (3 out of 10) ganglia were devoid of protein gene product 9.5-immunoreactive neurons, but NADPH-diaphorase-stained granules were found within the ganglia. However, all those neurons that were immunopositive to protein gene product 9.5 also expressed NADPH-diaphorase. Moreover, NADPH-diaphorase-positive neurons in the gallbladder of 2 to 4-day-old and 6-month-old guinea-pigs were found to express nitric oxide synthase.