Connective Tissue Fibers. Let's focus on the fibrous material created by fixed cells in connective tissue. Tissue fibers are classified based upon the type and 'weave' the fibers create. There are different types of weave, just like we have different types of fabric which make up our clothes.
The most difficult college to get into in the country, the California Institute of Technology, accepts less than one student for every 11 applicants.
As far as the recruiting process, I believe the Air Force is the hardest to get into. They also have the easiest and shortest basic training at about six weeks. Day-to-day life in the Air Force, for most MOS's, is more like a business environment than a military one.