THE FOAM PRODUCTION SYSTEM OF THE MALE JAPANESE-QUAIL - CHARACTERIZATION OF STRUCTURE AND FUNCTION

The research described here characterizes a unique neuromuscular syste m involved in reproductive behavior - the foam production system of th e male Japanese quail (Coturnix japonica). Male quail produce a large amount of foam that is transferred to the female during copulation, en hancing male fertilization success. The source is the foam gland compl ex, a large sexually dimorphic, androgen sensitive, external protubera nce of the dorsal cloaca, consisting of glandular units interdigitated with striated muscle fibers of the sphincter cloacae muscle (mSC). El ectromyographic (EMG) analysis of mSC activity in freely moving males interacting with females revealed different characteristics of the EMG signal during copulation, voiding of excreta, and other mSC movement. The amount of mSC activity and also the amount of foam produced were greatly increased by the presence of a female behind a screen. Denerva tion of mSC eliminated normal mSC movement and also abolished foam pro duction, confirming that mSC activity is the mechanism for foam produc tion. The spinal cord locations of the motoneurons innervating the maj or cloacal muscles, including mSC, were determined by injecting choler a-toxin conjugated horseradish peroxidase into each muscle. Labelled s omata with multiple primary dendrites were located in Area IX of the l ateral motor column of synsacral segments 7, 8, or 9 or 8, 9, and 10, The motoneurons serving mSC were intermingled with those projecting to the other cloacal muscles, but there were differences in the rostral- caudal placement of these neural populations. Thus mSC activity is an integral part of the male's reproductive behavior, mSC activity can be socially stimulated, and mSC activity occurring in anticipation of co pulation is likely to be functionally significant. Continued investiga tion of this highly accessible system has the potential to shed light on the mechanisms by which complex motor acts are produced and hormona lly regulated.