Penile vibratory stimulation yields increased spermatozoa and accessory gland production compared with rectal electroejaculation in a neurologically intact primate (Saimiri boliviensis).

Assisted reproductive techniques require an efficient semen collection procedure in cases of ejaculatory dysfunction. Anejaculation may be of psychogenic or neurogenic origin but can be overcome with stimulatory techniques. Penile vibratory stimulation (PVS) therapy for anejaculation has recently emerged as an alternative to rectal probe electroejaculation (RPE) and more invasive testicular procedures. Comparison of the stimulatory procedures in neurologically intact subjects is not ethically possible due to the discomfort involved with electroejaculation, and comparison in spinal cord injured men may be compromised due to the intricate effects of chronic denervation on semen quality. We have previously shown the efficacy of PVS in a non-human primate, the squirrel monkey. A cross-over study design comparing semen collected by PVS and RPE was employed during the breeding season in which 15 donor males were divided into two groups. One group received PVS and the other RPE, then, three days later, treatments were reversed. Twelve of 15 animals responded to PVS (80%), all with spermatozoa in the ejaculate. Mean volume (436 +/- 90 microl), motility (80.6 +/- 4.3%), and total spermatozoa (32.8 +/- 10.2 x 10(6)) were significantly higher than in the semen after RPE. RPE resulted in ejaculation in all 15 animals with a semen volume of 205 +/- 25 microl, but fewer samples contained spermatozoa (9/15) resulting in a low total count (0.5 +/- 0.3 x 10(6)). The motility was reduced in those samples with spermatozoa (n = 9; 44.1 +/- 11.4%). Additionally, accessory gland activity was measured via the seminal vesicle and prostrate markers, fructose and citric acid, respectively. The PVS specimens had significantly more fructose (2.9 +/- 0.7 mg/ejaculate) and citric acid (0.46 +/- 0.14 mg/ejaculate) compared to RPE collected specimens (1.2 +/- 0.3 mg/ejaculate and 0.24 +/- 0.04 mg/ejaculate, respectively). In conclusion, PVS produces a much greater sperm yield and increased accessory gland secretion compared to RPE in our neurologically intact squirrel monkey model.