The influence of stress on the adrenals of the springbok (Antidorcas marsupialis).
The absolute and relative adrenal mass as well as histological sections of the adrenals of springbok (Antidorcas marsupialis) (n = 76; 36 ewes and 39 rams) were studied over a period of 12 months. No significant difference was found in the absolute mass of the adrenals of rams and ewes. However, a significant difference (p < 0.01) was found in the relative masses (adrenal mass in terms of carcass mass), in that relative masses in males were greater than females. The zona fasciculata was found to be enlarged during the dry season (February and March), and showed increased activity in both sexes. The zona fasciculata of the ewes showed an additional increase in activity during September (late pregnancy) and October (lactation). In rams increased activity of the zona fasciculata was seen during the mating season in April and May. It appears that stressful events during reproduction and during the dry season cause an increase in adrenal mass and activity.