guereza: a colobus monkey with a reddish brown coat and white silky fringes down both sides of the body
placental: mammals having a placenta; all mammals except monotremes and marsupials
rheumatoid arthritis: a chronic autoimmune disease with inflammation of the joints and marked deformities; something (possibly a virus) triggers an attack on the synovium by the immune system, which releases cytokines that stimulate an inflammatory reaction that can lead to the destruction of all components of the joint