Eighteen months after coming out gay in the pages of Sports Illustrated, Jason Collins announced his retirement from the NBA in the same publication.

The 35-year-old Collins played 22 games with the New Jersey Nets last season, ending his career with the same team where he got his start in the NBA 13 years earlier.

“It has been 18 exhilarating months since I came out in Sports Illustrated as the first openly gay man in one of the four major professional teams sports,” Collins wrote. “And it has been nine months since I signed with the Nets and became the first openly gay male athlete to appear in a game in one of those leagues. It feels wonderful to have been part of these milestones for sports and for gay rights, and to have been embraced by the public, the coaches, the players, the league and history.”

Since Collins' coming out, the NFL drafted its first openly gay player, Michael Sam, who is currently unsigned, and professional soccer welcomed its first gay player, Robbie Rogers.

(Related: Robbie Rogers signs extension with LA Galaxy.)

Collins added that he knows other professional athletes who are gay.

“There are still no publicly gay players in the NFL, NHL or major league baseball. Believe me: They exist. Every pro sport has them. I know some of them personally. When we get to the point where a gay pro athlete is no longer forced to live in fear that he’ll be shunned by teammates or outed by tabloids, when we get to the point where he plays while his significant other waits in the family room, when we get to the point where he’s not compelled to hide his true self and is able to live an authentic life, then coming out won’t be such a big deal. But we’re not there yet,” he said.

(Related: Michael Sam named one of GQ's “Men (and women) of the Year.”)