Non-invasive collection of ejaculates from the common marmoset (Callithrix jacchus) using penile vibrostimulation

Penile vibrostimulation (PVS), a noninvasive repeatable method, has been shown in the squirrel monkey to yield semen of higher quality than rectal probe electro-ejaculation (RPE). The present study aimed at establishing the conditions for PVS to collect ejaculates from marmoset monkeys. Ten adult males were trained on the appropriate handling before each was subject to six to 12 PVS tests. Ejaculation was stimulated using a FertiCare personal vibrator fitted with a 2 cm x 0.5 cm i.d. glass tube. The stimulus was repeatedly applied over a frequency of 75-95 Hz and amplitude of 1-2 mm for up to 20 min. Ejaculates were analyzed for volume, total sperm number, sperm concentration, and proportion of living and motile sperm. Ejaculates were obtained in 31 of 88 PVS tests; 87.1% of the ejaculations occurred at 80-85 Hz frequency and 1-1.5 mm amplitude. In 18 tests ejaculates were produced within 49.7 seconds. Ejaculates were characterized by (mean values): volume 31.9 microl, total sperm number 34.2 x 10(6)/ejaculate, concentration 1,154.2 x 10(6) sperm/ml, live sperm 74.6%, motile sperm 59.6%. Total number and concentration of spermatozoa were significantly enhanced in singly living males. PVS yielded three to four times more spermatozoa than comparable previously published values for RPE. Enhancing the success rate by preselecting males for responsiveness may render PVS the sperm collection method of choice in marmoset monkeys.