The common marmoset, Callithrix jacchus, is used as a New World monkey species in
biomedical studies because of its small body size and good reproduction in captivity. A
modified artificial insemination technique was developed in this species to encourage
breeding of lines carrying interesting genes and traits. Fresh semen was collected by penile
vibratory stimulation. Medium containing highly motile sperm was inseminated into the
uterus using a catheter. Seven females were inseminated using freshly prepared sperm
from different males every day for 3 days including the expected ovulation day. As a result,
four females conceived, and three females delivered six offspring in total (two singletons
and one quadruplet). The paternity of the newborns was determined using microsatellite
markers to accurately pinpoint the timing of insemination and ovulation. It is expected
that our artificial insemination protocol can be effectively used to establish marmoset lines
and genetically manage marmoset colonies.