Rose Isabel Williams, Tennessee Williams' sister, who was the model for the character of Laura Wingfield in "The Glass Menagerie" and who echoed in many other Williams characters, died Sept. 6 of cardiac arrest at age 86 at a hospital in Tarrytown, N.Y.

Born in 1919 and raised in the same stressful household as her brother Thomas (later Tennessee), she spent most of her life from 1943 on in mental institutions following a prefrontal lobotomy authorized by her mother, Edwina.

It was Tennessee's belief that his sister's growing instability was caused, in no small part, by the strains between her strict Victorian upbringing, enforced by Edwina, and Laura's powerful but bottled-up sexual desires -- a theme he explores in his play Summer and Smoke, currently being revived on Broadway.

Rose was diagnosed as schizophrenic, but Tennessee was so appalled by the lobotomy and its effects on Rose, who had been his primary childhood friend, that he spent the rest of his life obsessing about it, according to accounts in various biographies.

In his play Suddenly Last Summer, a matriarch schemes to have a young woman lobotomized to keep her from revealing a terrible secret about her son's sexual predilections. The final scene of Williams' A Streetcar Named Desire, in which the increasingly unstable Blanche DuBois is carried off to a mental institution, reliant now on "the kindness of strangers," captures Williams' horror at his delicate sister's fate. In his first hit, the "memory play" Glass Menagerie, Williams created the character of the fragile-as-glass Laura, known to her Gentleman Caller as "Blue Roses," which is based directly on Rose.

In Williams' play, the character of Tom, based on himself, speaks to the sister's memory, saying, "Perhaps I am walking along a street at night, in some strange city, before I have found companions. I pass the lighted windows of a shop where perfume is sold. The window is filled with pieces of colored glass, tiny transparent bottles in delicate colors, like bits of a shattered rainbow. Then all at once my sister touches my shoulder. I turn around and look into her eyes . . . Oh, Laura, Laura, I tried to leave you behind me, but I am more faithful than I intended to be!"

Upon his death in 1983, Williams left the bulk of his fortune in a trust for Rose's care.

The third Williams sibling, Dakin, is still living, in Illinois.

Alliance Theatre of Atlanta is planning a major revival of The Glass Menagerie Oct. 10-Nov. 15, with Janice Akers as Laura.

-- By Robert Viagas