Geissmann, T.; Manella, B. & Zachmann, M. 1992: Skin glands and steroid hormones in gibbons and the great apes. In: Abstracts, Tenth Congress of ECRO, Munich, Germany, August 23-28, 1992, p. 43, Munich.

Skin glands and steroid hormones in gibbons and the great apes

T. Geissmann1, B. Manella2 & M. Zachmann2

Anthropological Institute, University Zürich-Irchel, Switzerland
2Kinderspital, Medizin. Klinik, Zürich, Switzerland

Many primates and other mammals possess specialized glandular concentrations in the sternal area which are commonly used for marking behaviour. Sternal glands also occur in the gibbons or lesser apes (Hylobates spp.) and orang-utans (Pongo pygmaeus) of East Asia. In these species, sternal glands are apparently not used for any kind of marking behaviour. The sternal glands of gibbons show histological similarities to the axillary glands of humans and the African apes (chimpanzees and gorillas). In addition, secretory activity of both types of glands appears to increase in similar situations: during stress and elevated temperature, suggesting similarities in function (Geissmann, 1987: Int. J. Primatol. 8:1-15). Chemical composition of these glandular secretions have apparently not been analysed previously, except for the axillary secretions of humans. For the present report, skin secretions of several species of gibbons, of orang-utans and chimpanzees were collected and radioimmunoassays (RIA) were carried out in order to check for the presence of the following three steroid hormones: Dehydroepiandrosterone (DHEA), Androstenedione, and Testosterone. This study presents first evidence that high sternal hormone concentrations occurring in some of the study animals cannot be the result of a simple filtration of hormones out of the blood plasma, but must be the result of a more complex accumulation process. Particularly androstenedione appears to be highly concentrated in the sternal glands of some gibbons and may be of importance in olfactory communication. This finding further supports the view that sternal glands in gibbons and axillary glands in humans and African apes may fulfil similar functions.

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