She peeks through the wooden door and walks into the convent parlor, her long black skirt brushing the polished floor, her face soft and pale as she stops at the thick barrier separating her from an afternoon visitor.

For the last 43 years as a cloistered nun, Mother Mary Gabriel of the Sisters of Visitation in Bethesda has said no to marriage, career, vacations, chocolate nut sundaes, high heels, Johnny Carson, shopping centers and art galleries.

"But who," she asks joyfully, "can say no to the Holy Father?"

Mother Gabriel and nine other cloistered nuns at the Bethesda convent plan to emerge from years of meditation and seclusion to attend the Oct. 7 address by Pope John Paul II at the Shrine of the Immaculate Conception. For some of these nuns, the event marks the first time in 25 years that they have left the convent walls for anything other than a doctor's appointment.

"These days," says Mother Gabriel, "you've got to get out for some things."

Indeed, when the traveling pope looks out at his flock of 4,000 nuns at the special address, about 100 among them will be members of cloistered orders.

"Going out next month to see the pope will be the first time in 55 years I've even been to another church," gushes another Bethesda nun, Sister Marie Therese.

Sister Mary Louise, who served as a Marine staff sergeant during World War II, stands at attention in mock salute. "Life is exciting enough here," she says, dismissing the notion of cloistered nuns defecting once they see what is beyond the convent walls.

"But I'm sure she'll count us coming and going," says another, giggling.

These nuns, who refer to their convent as the "Prayer Factory", will take time out from their rigorous schedule to ride a chartered bus to the pope's address. They will not attend the mass on the Mall.

Although the seven cloistered convents in the Washington area received special papal permission recently to attend the pope's address, not all the cloistered nuns are willing to accept the dispensation.

"There are so few opportunities for us to offer special sacrifice," said Sister Margaret Mary, a member of the Colletine Poor Clares of Alexandria. "Our special gift to the pope will be not to attend."

But for others, the attraction of seeing Pope John Paul II is too strong.

"We jumped at the chance to go," said Mother Mary Helen of the Washington order of Poor Clares.

But Mother Helen said the Alexandria Poor Clares are "much stricter" than the Washington group. "They go barefoot," she said. "We wear sandals."

The Georgetown branch of the Sisters of Visitation is planning to attend, as well as the Oblate Sisters of the Blessed Sacrament in Brookville, Md., and the Sisters of the Cross of the Good Shepherd in Northwest Washington.

And no one is worried about what to wear. "Maybe I'll put on a fresh bib," quipped one.

But while some area convents have taken on the air of a sorority house the night before the prom, there is some confusion among the other contemplatives, sparked by veiled criticism of sisters who may pray out the pope's visit.

"We've had a lot of pressure," said Mother Theresa, who heads the Port Tobacco, Md., Carmelite convent.

The sisters there said last week they would not be "coming out" for the pontiff's visit. This week, however, the office of the Shrine of the Immaculate Conception received word that the strictly cloistered order would be attending.

"We're still trying to decide," Mother Theresa said yesterday. The pressure, she added, was coming from friends who are urging them to attend the "once in a lifetime" service.

"We don't expect people to understand us," she said wearily. "Whether we go or not."

Then there was the story that the Port Tobacco nuns had come out once before during the last papal visit 13 years ago, and had been promptly told by the pontiff to go back inside the convent and pray.

"Where did you hear that?" Mother Theresa exclaimed. "They must be confusing us with the pope's trip to Palestine where he said he was grateful for those nuns who came, but also praised the ones who stayed inside."

Sister Margaret Culbert, who is coordinating the pope's address to the nuns, said yesterday that the religious orders preferred the word "contemplative" to the more established phrase "cloistered."

"You know, people associate 'cloistered' with medieval dungeons and monasteries," she said. However, the nun noted that life behind the convent walls was not as attractive as it used to be.

"Some people think of it as being very weird," she said.