title: The interaction between epidermal growth factor and matrix metalloproteinases induces the development of sweat glands in human fetal skin.
abstract: BACKGROUND
  The development of sweat glands is a very complicated biological process involving many factors. In this study, we explore the interrelationship among epidermal growth factor (EGF), matrix metalloproteinase 2 (MMP-2), matrix metalloproteinase 7 (MMP-7), and the development of sweat glands in human embryos. Furthermore, we hope to elucidate the mechanism(s) underlying the induction of epidermal stem cells into sweat gland cells.
  
  
  METHODS
  Skin biopsies of human embryos obtained from spontaneous abortions at different gestational ages from 11 to 31 weeks were used in this study. The dynamic expression of EGF, MMP-2, MMP-7, and keratin-7 (K7) in developing sweat gland cells or extracellular stroma surrounding the sweat gland cells was examined with SP immunohistochemical methods. The localization of the cellular sources of MMP-2 and MMP-7 was examined with in situ hybridization.
  
  
  RESULTS
  At 14-20 weeks of gestation, a gradual increase in EGF immunoreactivity was observed not only in developing sweat gland buds but also in extracellular stroma surrounding the buds, and the expression intensity of EGF peaked at 20-22 weeks of gestational age. All mRNA-positive buds or cells in developing sweat glands contained corresponding immunoreactive proteins. Positive immunostaining for K7 appeared in early sweat gland buds at 14-16 weeks of gestation, and from then on, the positive signal of K7 was concentrated in developing sweat gland cords or cells.
  
  
  CONCLUSIONS
  The morphogenesis of sweat glands in human fetal skin begins at 14-16 weeks of gestational age, and is essentially complete by 24 weeks. There is a close relationship among EGF, extracellular matrix remodeling, and morphogenesis of the sweat glands. EGF is one of the inducers in the development and maturity of sweat gland buds or cells.
authors.affiliation: Wound Healing Unit, Burns Institute, 304th Hospital, 51 Fu Cheng Road, Beijing 100037, People's Republic of China.
authors.forename: Jianfu
authors.initials: J
authors.lastname: Li
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Fu
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Sun
authors.forename: Tongzhou
authors.initials: T
authors.lastname: Sun
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Sheng
mesh_terms: D005314:Embryonic and Fetal Development; D004815:Epidermal Growth Factor / Q000502:physiology*; D005333:Fetus / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D053552:Keratin-7; D007633:Keratins / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000502:physiology*; D020783:Matrix Metalloproteinase 7 / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D012867:Skin / Q000196:embryology*; D013194:Staining and Labeling; D013545:Sweat Glands / Q000196:embryology*
chemical_list: C507497:KRT7 protein, human; D053552:Keratin-7; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D007633:Keratins; D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2