Description of the postcloacal glands of Plethodon cinereus, the red-backed salamander, during bouts of scent marking

Plethodon cinereus, the red-backed salamander, is a small territorial verte brate that defends refugia located on the forest floor. As a component of t erritorial defense, these animals use scent marks to advertise their refugi a, Behavioral evidence indicates that scent marks are produced by the postc loacal glands located on the ventral surface of the tail just posterior to the cloaca. We placed animals on unmarked substrates and recorded changes i n serous acini from the postcloacal and shoulder region over a 48-h period. Within the first hour there was an increase in the number of acini filled with secretory product in the postcloacal region, At 12 h the number of ful l:acini decreased and the number of empty acini increased. By 24 h the numb er of empty acini had decreased and the number of renewing acini containing secretory cells producing product had increased. By 48 h the ratio of full to empty to renewing acini was similar to those observed at the start of t he study. In the shoulder region, no significant changes in the ratio of fu ll to empty to renewing acini were observed. Observations of the serous aci ni within the postcloacal region and the shoulder region indicate that the mode of secretory production is holocrine. These findings are additional ev idence that the postcloacal glands are the site of scent mark production. ( C) 1999 Wiley-Liss, Inc.