Microanatomy and bacterial flora of the perineal glands of the North American porcupine

The perineal glands of the porcupine, Erethizon dorsatum (L., 1758), are sexually dimorphic, paired pockets sprouting osmetrichial hairs. They lie between the anus and urethra, lateral to the midline, amid a sebaceous glandular expanse. In their active state, the glandular pockets secrete an amber substance with a terpenoid odor. When inactive, the glands produce no stain or odor. In males, activation of the glands is associated with fully descended testes. The glandular pockets yield a microbiota ("microflora") in both their active and inactive states. We hypothesize that the active-state microflora transforms a sebaceous secretion into a pheromonally active product that is disseminated by anal dragging. The glandular microflora. was characterized by gas chromatography of bacterial fatty acid methyl esters (GC-FAME) and polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE) of 16S ribosomal RNA gene fragments of bacteria. PCR-DGGE results showed the resulting bacteria profiles were the same in both sexes, but differed between the active and inactive states. Active-state microfloras were dominated by members of the Actinobacteria and showed greater coefficients of similarity than inactive-state microfloras. The microflora of individual animals changed with time and with secretory state. We argue for a reproductive role for the activated perineal glands.