Scent glands sternal

Dimorphic sternal scent glands have been documented in several genera of the New World metatherian family Didelphidae, including Didelphis, Marmosa, and Monodelphis (Schaffer, 1940 Barnes and Barthold, 1969 Boggs, 1969 McManus, 1974 Pippitt, 1976 Barnes, 1977 Hunsaker and Shape,... 

Koontz, F. W. 1984. Sternal Gland Scent Communication in the Rufous Elephant-Shrew, Elephantulus Rufescens Peters, with Additional Observations on Behavior and Reproduction in Captivity. Dissertation, University of Maryland, College Park, Maryland. 

Some ant species (Formicidae) use nitrogen heterocycles as trail pheromones others however use hydrocarbons or alcohols (Fig. 8.62). In the rectal glands of a few Lasius and Formica species, 3,4-dihydroisocoumarins have been identified. The scents are emitted by exocrine glands like the poison apparatus or the sternal gland. The trail pheromone of the leafcutter ant (Atta texana) is effective at extremely low concentrations of 80 fg/cm (If = 10" ). One milligram of methyl 3-methylpyrrole-2-carboxylate is sufficient to lay a trail three times around the Earth. 

The sexual dimorphism in cutaneous gland activity indicated by the sternal stain in male opossums is readily apparent at the histological level during the breeding season. The sternal skin of males is a site of hypertrophied sebaceous and sudoriferous gland units and well adapted for odor collection and dispersion. The folding of the skin surface provides a likely area for bacteria to collect and aid in the degradation of exudate and odor production, as well as an increased surface area for scent dispersal. 

Scent-marking in marsupials. In addition to using specific anal-cloacal, and sternal glands, marsupials use saliva, urine and feces in chemical communication (Eisenberg and Golani, 1977). Other specific glands, such as frontal glands and parts of the body (such as the flank), are also used (Schultze-Westrum, 1965, 1969 Fadem and Cole, 1985). 

In a recent study of scent-marking behavior in the koala, cinereus (Thompson and Fadem, unpublished observations) a conspicuous sternal gland, seen only in adult males, was used in chest-marking (Fig, 4), In chest-marking, the male koala stood upright, lowered its forelimbs to the side, placed the gland over the area to be marked, and flexed and extended... 

Chest-marking in the koala occurred primarily upon introduction to an unfamiliar tree and declined thereafter. Females rarely chest-marked (only one chest mark was seen in over 20 15-min trials), and highest levels of chest-marking behavior were seen in males 5-10 years old males 1-2 years old marked less frequently (Fig. 5). This is probably related to the fact that puberty occurs at between 1 and 3 years of age and the sternal gland first appears at about 1 year of age in this species (Thompson, personal communication). Thus, age, sex, and time-related aspects of scent-marking in the koala were remarkably similar to those seen in the gray opossum (c.f.. Fig. 1). 

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