When literature professor Joy Ladin returned to New York's Yeshiva University at the start of term last week, her pink lipstick and black skirt, stunned colleagues.
For just two years ago Joy, 47, was a man known as Jay.
And the transformation has shocked many because the academic, poet and author has remained a member of the faculty at the Orthodox campus.
Although Prof Ladin and YU refuse to comment publicly, many were outraged at the thought of a transgender teaching in a Jewish institution.
Rabbi Moshe Tendler, a senior dean, said: "He's not a woman, he's a male with enlarged breasts. He's a person who represents the kind of amorality which runs counter to everything the university stands for.
"There is no niche where he can hide out as a female without being in massive violation of Torah law."
The clash with YU started at the end of 2006 when, just a few weeks after it awarded Prof Ladin tenure, he told authorities that he was in the process of becoming a woman.
Though he was placed on indefinite leave, after much heated debate, he was allowed to return, although as a she.
Some faculty members suggested that YU had been legally forced into the decision, because Prof Ladin had already been granted tenure.
But many students insisted they had no objections. Sarah Rindner, 25, said: "I'm sure the university won't regret it."
Meanwhile, as Prof Ladin continues to take progesterone and oestrogen to grow breasts, the professor's wife has left the family home in Amherst, Massachusetts, and filed for divorce and custody of their three children.