title: Fetal Rat Gubernaculum Mesenchymal Cells Adopt Myogenic and Myofibroblast-Like Phenotypes.
abstract: Gubernaculum-cremaster complex development is hormonally regulated and abnormal in a cryptorchid rat model. Using cell tracking techniques and imaging we studied myogenic phenotypes and fates in the fetal rat gubernaculum-cremaster complex.
  
  
  
  Embryonic day 17 gubernaculum-cremaster complexes were labeled with CellTracker™ or the DNA synthesis marker EdU (5-ethynyl-2'-deoxyuridine), or immobilized in Matrigel® and grown in culture. Embryonic day 17 to 21 gubernaculum-cremaster complex sections and cells were imaged using wide field and deconvolution immunofluorescence microscopy, and muscle and/or myofibroblast specific antibodies. Deconvolved image stacks were used to create a 3-dimensional model of embryonic day 21 gubernaculum-cremaster complex muscle.
  
  
  
  PAX7 (paired box 7) positive and myogenin positive muscle precursors were visible in a desmin-rich myogenic zone between muscle layers that elongated and became thicker during development. Gubernaculum-cremaster complex inner mesenchymal cells expressed desmin and αSMA (α smooth muscle actin) at lower levels than in the myogenic zone. After pulse labeling with CellTracker or EdU mesenchymal cells became incorporated into differentiated muscle. Conversely, mesenchymal cells migrated beyond Matrigel immobilized gubernaculum-cremaster complexes, expressed PAX7 and fused to form striated myotubes. Mesenchymal gubernaculum-cremaster complex cell lines proliferated more than 40 passages and showed contractile behavior but did not form striated muscle. Our 3-dimensional gubernaculum-cremaster complex model had 2 orthogonal ventral layers and an arcing inner layer of muscle.
  
  
  
  Our data suggest that mesenchymal cells in the peripheral myogenic zone of the fetal gubernaculum-cremaster complex contribute to formation of a distinctively patterned cremaster muscle. Nonmyogenic, desmin and αSMA positive gubernaculum-cremaster complex mesenchymal cells proliferate and have a myofibroblast-like phenotype in culture. Intrinsic mechanical properties of these divergent cell types may facilitate perinatal inversion of the gubernaculum-cremaster complex.
authors.affiliation: Pediatric Urology Research Laboratory, Nemours Biomedical Research/Alfred I. duPont Hospital for Children, Wilmington, Delaware.
authors.forename: Alan K
authors.initials: AK
authors.lastname: Robbins
authors.affiliation: Pediatric Urology Research Laboratory, Nemours Biomedical Research/Alfred I. duPont Hospital for Children, Wilmington, Delaware.
authors.forename: Abigail B
authors.initials: AB
authors.lastname: Mateson
authors.affiliation: Department of Biomedical Engineering, University of Delaware, Newark, Delaware.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Khandha
authors.affiliation: Pediatric Urology Research Laboratory, Nemours Biomedical Research/Alfred I. duPont Hospital for Children, Wilmington, Delaware.
authors.forename: Joan E
authors.initials: JE
authors.lastname: Pugarelli
authors.affiliation: Department of Mechanical Engineering, University of Delaware, Newark, Delaware; Department of Biomedical Engineering, University of Delaware, Newark, Delaware.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Buchanan
authors.affiliation: Tissue Engineering and Regenerative Medicine Research Laboratory, Nemours Biomedical Research/Alfred I. duPont Hospital for Children, Wilmington, Delaware; Department of Biomedical Engineering, University of Delaware, Newark, Delaware.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Akins
authors.affiliation: Pediatric Urology Research Laboratory, Nemours Biomedical Research/Alfred I. duPont Hospital for Children, Wilmington, Delaware. Electronic address: Julia.Barthold@nemours.org.
authors.forename: Julia Spencer
authors.initials: JS
authors.lastname: Barthold
mesh_terms: D000009:Abdominal Muscles / Q000166:cytology / Q000196:embryology*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D000071477:Gubernaculum / Q000166:cytology / Q000196:embryology*; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D024510:Muscle Development / Q000502:physiology*; D058628:Myofibroblasts / Q000502:physiology*; D010641:Phenotype; D051381:Rats; D020318:Rats, Long-Evans
keywords: cryptorchidism; fetal development; mesoderm; myofibroblasts; testis