Physiology and Dysfunction

Sue M. McDonnell, PhD

    Copulation normally culminates with two physiologically distinct events known as emission and ejaculation. Emission is the release of sperm and accessory gland fluids into the pelvic urethra. Ejaculation is the forceful expulsion of the combined fluids (i.e., semen) from the urethra. The associated perceptual-cognitive event called orgasm in humans has not been characterized in nonhuman species. The neuro-physiologic correlates of orgasm no doubt occur in animal species, so it is reasonable to posit that animals perceive some form of analogous satisfying perceptual resolution of copulation. This article begins with a brief outline of the physiology of emission and ejaculation followed by a discussion of related disorders in stallions.