A translation question about colleges

Recently, while reading a manga, I came across this phrase in describing a female college student:
"S女子大"
My question is: What does the S refer to?
I've tried searching Google and Goo (and Jref too!), but couldn't come up with anything definitive other than a bunch of AV sites that feature female college students.
I also came across similar phrases using "F" and "M":
"M女子大"
"F女子大"
If anyone can enlighten me on the designations, I would truly appreciate it!
And if I'm wrong to create a new thread here, my humblest apologies.

Initial in alphabets are used when one does not want to say the proper name i.e. to avoid mentioning which one he is actually referring, but people reading (or hearing) it can guess if they know the context.

There are several 女子大 that can be called S女子大 (meaning the name begins with either さ、し、す、せ、そ, such as 聖心女子大 and 清泉女子大).
Same goes with other two.
Without the context, it is difficult to make a correct guess.


Here's a List of 女子大
http://www.w-univ.net/

Thanks, undrentide. That really explains a lot! Since all I was getting was AV sites in my searches, just for an instant thought it had something to do with AV. But it just didn't fit in the context with the story I was reading! LOL! I truly appreciate your help!

どうもありがとうございます