Transabdominal palpations and ultrasonography (US)
examinations were performed to confirm pregnancy
30 days after AI. If AI was successful, the US examinations
were used to monitor embryonic development and prenatal
loss in pregnant females at approximate fortnightly
intervals throughout gestation until birth. Transabdominal
US examinations were carried out on unsedated females
held in a marmoset holder (CL-4532, CLEA Japan) using an
ultrasound machine (LOGIQ Book XP; GE Healthcare,
Tokyo, Japan) with an 8C-RS probe with 4- to 10-MHz frequency
range. The US examinations focused initially on the
appearance and size of the uterus and were then performed
to determine the number of fetuses at specific gestation
stages corresponding to Oerke et al. [20].