Marmoset flushes help Reproductive Research Services expand in 1997


(Left: WRPRC Research Associate Vivienne Marshall reaches for the flush apparatus while holding a cannula in place to perform a nonsurgical embryo flush on an anesthetized marmoset. Research Assistant Melissa Browne holds the culture dish used to catch the flush medium. Following this procedure Marshall will peer through the microscope to see whether the flush produced any embryos. By administering the drug prostaglandin, the Reproduction Research Services staff can time the ovulation of the marmoset colony's females so they all ovulate at roughly the same time. Thus, several flushes can be scheduled over just a few days per month, making it possible to collect multiple embryos for experimental purposes and making efficient use of staff time and resources. (Photo by Jordana Lenon.)

A local glassblower custom created the tiny speculum that staff at our Center used to perform the first-ever non-surgical embryo flushes on common marmosets (Callithrix jacchus) in 1993. The Center's shop crafted a diminutive cannula and other apparatus for use with the speculum.

"We've been doing this work in rhesus monkeys since 1990, which hasn't been easy because of their convoluted reproductive tracts," says Bob Becker, M.S., associate researcher and head of Reproduction Research Services at our Center. "Now we're doing these flushes successfully in marmosets, too, which is amazing because they are so small."

Reproduction Research Services provides investigators with materials, services and information regarding nonhuman primate reproduction. Our researchers and affiliates use embryos, oocytes and sperm from rhesus monkeys and marmosets to study fertilization, implantation, early placental development, and embryonic stem cell differentiation.

Thanks to the unit's breakthrough technology with the marmoset flushes, our Center celebrated a milestone last October, when three surrogate marmoset mothers each bore a set of twins after being nonsurgically implanted with transferred embryos. Due to this success, which has yet to be duplicated anywhere else, the embryo transfer program holds promise for increasing the number of rare and endangered New World primates. The new method can achieve a pregnancy rate as high as 40 percent, rendering invasive procedures obsolete.

Investigators at our Center can now also begin to manipulate normal embryos before implantation and study their early development afterwards with hopes of ultimately revealing causes of infertility, life-threatening pregnancy complications, genetic disorders and other reproductive and developmental problems in humans.

"Having this centralized service promotes the efficient use of embryonic and fetal material to ensure the greatest scientific productivity from a limited resource," Becker emphasizes. "We're a small unit, but we have over 50 years of combined experience in primate reproduction." This staff expertise, combined with adequate funding for the program, distinguishes the unit as the only reliable steady source of rhesus monkey and marmoset embryos in the world.

Another service the unit provides is ultrasound examinations to diagnose pregnancy and monitor reproductive status in rhesus monkeys. The staff also provides investigators with information on individual animals' reproductive cycles and helps schedule Cesarean sections for studies of fetoplacental development studies. The unit includes Becker; Vivienne Marshall, Ph.D., research associate; Steve Eisele, laboratory animal supervisor; Melissa Browne, B.A., assistant research specialist, and Lisa Knowles, M.S., assistant research specialist. James Thomson, Ph.D., D.V.M., began the marmoset flush program to support his research on how the first cells in life differentiate into either normal tissues or those harboring defects. Regarding 1997 goals, Marshall says, "We would like to get the marmosets to produce more eggs each month. This has been done in rhesus monkeys, with improving rates of success through various hormone combinations, but no one's attempted to hyperstimulate marmosets. It's going to be a major technical breakthrough when it happens."

Copyright 1997. Wisconsin Regional Primate Research Center.