title: A morphological and histological examination of the pan-tropical spotted dolphin (Stenella attenuata) and the spinner dolphin (Stenella longirostris) adrenal gland.
abstract: The morphology and histology of the cetacean adrenal gland are poorly understood. Therefore, this study examined 32 pairs of adrenal glands from 18 pan-tropical spotted dolphins (Stenella attenuata) and 14 spinner dolphins (Stenella longirostris). In both species, the cortex was pseudolobulated and contained a typical mammalian zonation. Medullary protrusions (0-3 per section) and a medullary band were identified in both species. For S. attenuata, no statistical differences were found in the cortex to medulla (CM) ratio or the percent cross-sectional area (PCA) of the adrenal glands compared with sex or sexual maturity. The mean CM ratio for S. attenuata was 2.34 and the PCA was 64.4% cortex, 29.4% medulla and 6.2%'other'. 'Other' indicates blood vessels, connective tissue and the gland capsule itself. For S. longirostris, there was no statistical difference in the CM ratio compared with sexual maturity. However, a statistical difference was found between the CM ratio and sex, suggesting sexual dimorphism (female CM ratio = 2.46 and males = 3.21). No statistical differences were found in the PCA of S. longirostris adrenal glands by sexual maturity. However, a statistical difference was found between the PCA by sex. Female S. longirostris adrenal glands consisted of 65.0% cortex, 27.3% medulla and 7.7% 'other', whereas male adrenal glands consisted of 71.7% cortex, 22.7% medulla and 5.6% 'other'.
authors: Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA. lance.clark@uaa.alaska.edu
authors: L S
authors: LS
authors: Clark
authors: D F
authors: DF
authors: Cowan
authors: D C
authors: DC
authors: Pfeiffer
mesh_terms: D000302:Adrenal Cortex / Q000033:anatomy & histology; D000311:Adrenal Glands / Q000033:anatomy & histology*; D000313:Adrenal Medulla / Q000033:anatomy & histology; D000818:Animals; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D008854:Microscopy, Electron / Q000662:veterinary; D012727:Sex Characteristics; D013045:Species Specificity; D050706:Stenella / Q000033:anatomy & histology*