The MVZ mammal collection is the fourth largest in the United States and the second largest such collection associated with a U.S. academic institution. It contains over 228,000 skin, skull, skeleton and fluid-preserved specimens. Over 33,700 are also represented by frozen or fluid preserved tissues. The collection includes 364 type specimens, making it the fourth largest collection of such specimens in the US. Karyotype (chromosome) preparations are available for ca. 4,000 rodent specimens. These consist of slides of chromosome preparations and, in some cases, black and white photos and/or 35 mm negatives of chromosome spreads. The mammal collection also houses large series of lab-raised specimens from research by Francis B. Sumner, Richard D. Sage, and William Z. Lidicker.