Below are four takeaways from the letter.

1. The NCAA's constitution states that "intercollegiate athletics programs shall be conducted in a manner designed to protect and enhance the physical and educational well-being of student-athletes."

The letter said there are "serious concerns" about MSU's adherence to the constitution.

2. Members of the NCAA are expected and required to report possible violations of NCAA rules and policies, according to the letter.

But, as of Jan. 23, MSU had not sent any information about Nassar's actions, affected student-athletes, his role as a team physician, operation of athletic departments, or the involvement of those on campus, among other things, according to the letter.

"While it's understandable that various investigations must run their course and criminal and civil matters will take time to conclude, we do not believe a wait-and-see approach is proper in this matter," the letter said.

3. The first step in the investigation requires MSU to send information regarding any possible violations of NCAA legislation in a "timely manner" to  NCAA Vice President Jon Duncan.

4. The NCAA understands ongoing criminal and governmental investigations take priority, but still expects an "expeditious response," the letter concludes.