The failure in these cases is believed to be due to poor semen quality. The Miami Project's Male Fertility Research Program focuses on characterizing the abnormalities in semen samples from SCI men and trying to determine what may be causing poor semen quality. Nancy Brackett, Ph.D. , organized the program in 1991, and works in collaboration with Charles Lynne, M.D. , of the University of Miami Department of Urology to investigate the causes and potential treatments for infertility in SCI men. Spinal neurons controlling ejaculation are located in the lower part of the spinal cord, specifically, the thoracic, lumbar and sacral cord. Normal ejaculation involves coordinated nervous system signals travelling between the brain and the spinal cord.
Ejaculation is really a two-step process.
In the first step, emission, fluids are secreted from the accessory glands and, in the second step, the semen is forcibly expelled from the penis. If there is an interruption in the nervous system connections between the brain and these areas of the spinal cord, ejaculatory function is disrupted. Whether the goal is assisting reproduction or scientific research, methods now exist to obtain sperm from SCI men by assisted ejaculation. One method uses a special vibrator to deliver mechanical stimulation to the penis. The frequency and strength of the vibratory stimulus are important in obtaining a response.