Myometrial smooth muscle cells (MSMC) are located in the myometrium between the endometrium and the serosa of the uterus. MSMC are involved in the stretching of the uterus during pregnancy and are also responsible for uterine contractions during labor. To accommodate the growing embryo, the myometrium expands through smooth muscle cell hypertrophy and hyperplasia. Typically, the uterine myometrium consists of differentiated smooth muscle cells, but in certain pathological conditions, such as uterine leiomyomata, smooth muscle cells in the myometrium proliferate abnormally to form tumors. Studies indicate that platelet-derived growth factor (PDGF) may stimulate MSMC proliferation and consequently may play a role in the formation of leiomyomata. Cultured MSMC are an excellent model to study the physiology of pregnancy and labor and the mechanisms that contribute to the development of uterine leiomyomata. HMSMC from ScienCell Research Laboratories are isolated from human uterus. HMSMC are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HMSMC are characterized by immunofluorescence with antibodies specific to α-smooth muscle actin. HMSMC are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast, and fungi. HMSMC are guaranteed to further expand for 15 population doublings under the conditions provided by ScienCell Research Laboratories Recommended Medium It is recommended to use Smooth Muscle Cell Medium (SMCM, Cat. #1101) for culturing HMSMC in vitro.