http://en.wikipedia.org/wiki/Platelet
Now, I know what you're thinking....jesus christ, I have to read this whole thing? Actually....Just use the word find function...
ctrl + F....press both at the same time, and enter nucleus for your word search.
The internet is a powerful tool smooth operator...it has the ability to answer most if not all of your questions. Oh and those heavy objects in your room...those are called books, yeah I know you thought they were there to make your room look all sophisticated and all. However, they are actually there for you to look up information!!! Wow, such a novel function from such a primitive looking entity, I know. For example, you may have a question, like you did, regarding platelets...well, you would simply flip to the index of the book, which is usually located at the end, and all pages with information pertaining to platelets will come up. Chances are, you will find the answer accordingly.