Teratoma formation by human embryonic stem cells is site dependent and enhanced by the presence of Matrigel.

When implanted into immunodeficient mice, human embryonic stem cells (hESCs) give rise to teratoma, tumor-like formations containing tissues belonging to all three germ layers. The ability to form teratoma is a sine qua non characteristic of pluripotent stem cells. However, limited data are available regarding the effects of implantation site and the methods employed for implantation on the success rate of teratoma formation.

Immunohistochemical characterization of cloned lamb nephropathy.

Kidneys from lambs derived by nuclear transfer are frequently abnormal and are characterized by an enlarged pelvis and narrow medulla, consistent with lower urinary tract obstruction and development of variable hydronephrosis. The precise pathogenesis of this entity is unknown. Immunohistochemical staining for intermediate filaments was used to further characterize the lesions seen in this condition and was compared with age-matched control tissue.