In 1961, George Balanchine summoned some of the nation's top ballet teachers to a seminar in New York, hub of the U.S. dance world and one of the few cities where professional ballet was being performed at the time.

"Something has to happen," said the great choreographer and founder of the New York City Ballet and its School of American Ballet. "You're turning out more and more dancers. Where are they going to dance?"

"If you really are serious, Mr. B.," said Barbara Weisberger, who had been his first child student (at age 8) when he opened his New York school in 1934, "the place to start is Philadelphia."

"Well, Barbara, my smart ballerina," he said, "you must do it."

With that, Philadelphia was thrust into the forefront of the burgeoning regional ballet movement. In the years that followed, Weisberger's Pennsylvania Ballet performed regularly in Philadelphia, toured extensively, and settled in as resident company at the Brooklyn Academy of Music in New York, where it was considered the equal of the City Ballet, American Ballet Theatre, and the Joffrey Ballet.

The seeds Balanchine scattered in 1961 are still blooming today. The Pennsylvania Ballet, Boston Ballet, Ballet West, and Cincinnati Ballet celebrate 50th anniversaries this year; other troupes will reach that mark in the next year or so.

The Pennsylvania Ballet opens its 50th-anniversary season Thursday at the Academy of Music with the company premiere of Balanchine's lush three-part plotless ballet, Jewels.

Related festivities will included a free performance at the academy on Oct. 20 (to be broadcast later on PBS), a "Nutcracker Market" at the Kimmel Center Dec. 6-8, months of exhibits at the Free Library and the airport, and a tutu project in conjunction with Moore College of Art.

Weisberger's proposal that the Balanchine campaign begin in Philadelphia made sense.

Now 87, Weisberger - who lives in Kingston, Luzerne County, and still teaches - notes that Balanchine had recruited his first dancers from Philadelphia, from Catherine Littlefield and her family, who from 1935 to 1942 ran an influential school and company called, briefly, the Littlefield Ballet, then the Philadelphia Ballet. It was the first American classical ballet troupe to tour Europe; it performed at the White House, the Hollywood Bowl, and the New York World's Fair. And some of its dancers had formed the core of Balanchine's nascent School of American Ballet.

So when Weisberger was ready to launch her Philadelphia company, Balanchine was happy to assist: "They helped me and I'll help you. It's a debt repaid."

At his suggestion that she begin by working with an existing arts organization, for two years her dancers performed with the Philadelphia Lyric Opera Company. He nudged her with his oft-quoted line "but first a school," to train her future dancers before getting in too deep. And in April 1963, when the Ford Foundation awarded Weisberger a $45,000 grant, Balanchine gave her new troupe permission to perform many of his masterpieces free of charge.

On July 12, 1963, the Pennsylvania Ballet made its debut at a Paoli estate. Balanchine - listed on the program as artistic adviser - joined Ford Foundation representatives and an audience of 900 on the expansive lawn to watch.

Balanchine's legacy

The direct line from the master to the stage of the Academy of Music continues today in the form of Pennsylvania Ballet soloist Gabriella Yudenich.

But first it descended from Balanchine to Weisberger to Yudenich's mother, Barbara Sandonato - now 70, living in Cherry Hill, and teaching ballet.

She was a teenager in 1961, sharing the barre at the School of American Ballet with Suzanne Farrell, Patricia McBride, and other future City Ballet luminaries when Weisberger walked in.

At 5-feet-3, Sandonato had wondered about her chances of making it into City Ballet. Her interest was piqued when she noticed the woman in the persimmon-colored dress and jacket. "She appeared in the door with Balanchine. She was just standing there, totally into the feeling of the class."

And Weisberger, scouting for her new company, noticed Sandonato. Soon, the petite dancer was invited to join the new Pennsylvania Ballet.

Despite the uncertain beginnings, or perhaps because of them, she leaped at the chance to join the pioneering regional movement. Balanchine had blazed trails, as had her early teacher, Lorna London, who toured North and South America with Balanchine's Ballet Caravan, a precursor to City Ballet. Sandonato wanted that kind of excitement.

Balanchine continued to nurture his protegee, allowing Weisberger to perform his works free, and lending his own company members to perform in Philadelphia.

"He gave me all these dancers that season, and if I could've kept them, I would've had the best dancers in the country," said Weisberger, who commuted for years between Philadelphia and Wilkes-Barre, where her husband and two children lived.

The early years were lean. Sandonato and another School of American Ballet recruit, Patricia Turko, shared an apartment; Weisberger slept on their couch when she was in town. Their paychecks barely kept them fed. But they were performing glorious choreography to increasing acclaim. And the company grew.

Another generation

In 1964, a company ballet master at a festival in Austria spotted a wonderful young dancer, Alexei Yudenich, 21, and knew the Pennsylvania Ballet had to have him. Yudenich also had an offer from the London Festival Ballet and said he'd join whichever company got him a visa first. The Pennsylvania Ballet won.

Sandonato and Yudenich became a couple on and off stage. They married, and together won medals in Bulgaria at the prestigious Varna International Ballet Competition, where he tied for first, getting a silver, and she was the first American to earn an award there, a bronze.

Yudenich suffered a career-ending injury in 1973, when the couple was with National Ballet of Canada. Sandonato returned to dance in Philadelphia for five more years, then retired. Yudenich died of cancer in 1990 at 46. Those early troupers were done.

Now it was Gabriella.

As a girl, Gabriella Yudenich wanted to be a paleontologist. She started and quit ballet many times. (At 6, she'd been an angel in the Pennsylvania Ballet's Nutcracker. Her brother, Ivan, played the Prince; he quit, too.)

"I never really saw the professional life of the ballerina, because my mother had retired years before I was born," Gabriella, 30, recalled. All she knew was that ballet was hard. "I just wasn't committed. I knew, of course, she was a ballerina and she was my mom, but it was not fun. The whole entire barre process in class: I hated it. It was boring. It hurt."

Then, when she was 11, she saw a video about a young dancer on the brink of greatness and something changed in her. She knew it was real this time.

As they drove home from one of Sandonato's teaching jobs, she poked her head forward from the backseat.

"Mommy," she said, "I know what I want to be when I grow up. I want to be a ballerina."

At 11, she was old for a serious start, but start she did, stretching every day before school and taking almost all her mother's classes. By 14, she'd been accepted by the School of American Ballet. At 18, she was guesting with the Pennsylvania Ballet and considering a career in New York when artistic director Roy Kaiser offered her a contract. She's been with the company since.

And like her parents, she found love there. She and Thomas Baltrushunas met briefly at a summer program at the American Ballet Theatre as teenagers but got together for real when both landed in Philadelphia. (He left the ballet in 2008 to return to school.) They have a 20-month-old son, Gavin.

So Balanchine's line continues: "Gabby, she's like my granddaughter," Weisberger says of the dancer who will debut in the "Rubies" section of Jewels Thursday night.

Will the family dance for another generation?

"I'm not going to put Gavin in ballet," Gabriella says, adding, "I will say this, he has a really good foot."