Working with embryonic stem cells from mice, researchers at Children's Hospital Boston/Harvard Medical School and the Whitehead Institute for Biomedical Research created a continuously growing line of embryonic germ cells - primitive cells in the embryo that mature to become sperm or eggs -- providing for the first time an opportunity to study this process in the Petri dish. In a second step, they created male gametes that were capable of fertilizing an egg to form an early embryo. The research is published in the Dec. 10 online edition of the journal Nature.

EMBRYONIC GERM CELLS
Embryonic germ cells are a unique group of cells that the embryo sets aside for future reproduction. An early embryo starts with only about 50 of these rare cells, making them very difficult to isolate and study. Using embryonic stem cells from mice, the researchers first created multi-cellular structures called embryoid bodies that have some characteristics of early mouse embryos and the beginnings of differentiated tissue (muscle, blood, etc.). The embryoid bodies were allowed to grow for 4-10 days.

Next, the researchers isolated germ cells from the embryoid bodies and cultured them in a dish along with growth factors. The result was a continuously growing line of embryonic germ cells. These methods now provide a cell culture system in which the unique properties of embryonic germ cells can now be more easily studied.

Parental imprints and cancer
First, the researchers want to study embryonic germ cells to better understand a set of genetic instructions called imprints. Imprints affect a small group of about 50 genes, many of which govern growth, and determine which copy of the ge
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Contact: Mary Ellen Shay
mary.Shay@tch.harvard.edu
617-355-6420
Children's Hospital Boston
10-Dec-2003