Table 1.

Size and occurrence of serotonin-immunoreactive neurons in DR cultures

Immunoreactivity	Diameter (μm)	Frequency (%)
Serotonin (+)	15.8 ± 0.3 (n = 250)	62.4 (n = 485)
Serotonin (−)	16.7 ± 0.5 (n = 108)	37.6 (n = 292)

Cell diameters were determined from two cultures. The frequency measurements were conducted on four cultures. For each batch of cultures, the measurements were conducted on 1/4 of culture area of a dish. All cultured cells were obtained from 10-day-old rats, and were cultured for 11 days. Diameter was defined as a geometrical mean of the major and minor soma diameters. Cultures were treated with the serotonin immunocytochemical method using the peroxide-antiperoxidase method (Sternberger, 1979). Diameters are expressed as means ± S.E.M.