It was 2 a.m. when Danielle Piergallini composed an email to classmates at Vanderbilt University’s Owen Graduate School of Management announcing she was transgender. She had spent her first semester in the M.B.A. program presenting as male and worried what kind of response she would get after she clicked “send.”

Students and professors had a swagger about them, a kind of “bravado,” she said, and at times it felt unfriendly. (Owen is 70 percent male; only 1 percent reported being L.G.B.T.Q. — lesbian, gay, bisexual, transgender, queer — in a survey last year at top business schools.)

“There were moments in the first semester when I wondered if I made a mistake,” she said. “Going into the type of male-dominated culture that is business school doesn’t necessarily send a positive signal to someone who wants to transition.”

So she was surprised when emails of support spilled into her inbox right away. Soon after, an administrator helped her figure out how to change her name in school records.