Massachusetts' highest court heard arguments yesterday over who should control four embryonic cells. Do they legally belong to the mother who wants to try one more time to have a baby? Or are they the property of her divorced husband, who does not want another child with his ex-wife?

• While the case is a first for Massachusetts' Supreme Judicial Court, legal observers report that similar disputes have arisen in Illinois, Michigan, Texas, Alabama and New Jersey.

• It is estimated that the number of frozen embryos now totals about 150,000.

• The Massachusetts case is unique in that the wife has seven consent forms signed by her ex-husband, saying that if the couple separate, the embryos belong to her.

• But earlier a family court judge had ruled that because the couple had given birth to twins since their agreement and had divorced, circumstances had changed and the ex-husband should not be held to the agreement.

In the absence of laws governing this form of conception and the reluctance of lawmakers to attack the subject, earlier court rulings have tended to flip-flop from one court to the next.

Legal experts say that a consensus on several issues has begun to emerge, however. First, embryos are considered neither children nor property -- but rather a "special entity" with a potential for life.

Second, whenever possible an agreement a couple signed with a fertility clinic about what to do with their embryos if the couple divorce or die should be considered a contract.

John A. Robertson of the University of Texas School of Law recently wrote: "The party wishing to discard wins, unless there is no other way for the party seeking implantation to reproduce."

Source: Carey Goldberg, "Massachusetts Case is Latest to Ask Court to Decide Fate of Frozen Embryos," New York Times, November 5, 1999.