Satellite cells are situated beneath the basal lamina that surrounds each myofiber and function as myogenic precursors for muscle growth and repair. The source of satellite cell renewal is controversial and has been suggested to be a separate circulating or interstitial stem cell population. Here, we transplant single intact myofibers into radiation-ablated muscles and demonstrate that satellite cells are self-sufficient as a source of regeneration. As few as seven satellite cells associated with one transplanted myofiber can generate over 100 new myofibers containing thousands of myonuclei. Moreover, the transplanted satellite cells vigorously self-renew, expanding in number and repopulating the host muscle with new satellite cells. Following experimental injury, these cells proliferate extensively and regenerate large compact clusters of myofibers. Thus, within a normally stable tissue, the satellite cell exhibits archetypal stem cell properties and is competent to form the basal origin of adult muscle regeneration.

Abstract. Skeletal muscle is one of a several adult postmitotic tissues that retain the capacity to regenerate. This relies on a population of quiescent precursors, termed satellite cells. Here we describe two novel markers of quiescent satellite cells: CD34, an established marker of hematopoietic stem cells, and Myf5, the earliest marker of myogenic commitment. CD34 ϩ ve myoblasts can be detected in proliferating C2C12 cultures. In differentiating cultures, CD34 ϩ ve cells do not fuse into myotubes, nor express MyoD. Using isolated myofibers as a model of synchronous precursor cell activation, we show that quiescent satellite cells express CD34. An early feature of their activation is alternate splicing followed by complete transcriptional shutdown of CD34. This data implicates CD34 in the maintenance of satellite cell quiescence.In heterozygous Myf5 nlacZ/ ϩ mice, all CD34 ϩ ve satellite cells also express ␤ -galactosidase, a marker of activation of Myf5 , showing that quiescent satellite cells are committed to myogenesis. All such cells are positive for the accepted satellite cell marker, M-cadherin. We also show that satellite cells can be identified on isolated myofibers of the myosin light chain 3F-nlacZ -2E mouse as those that do not express the transgene. The numbers of satellite cells detected in this way are significantly greater than those identified by the other three markers. We conclude that the expression of CD34, Myf5, and M-cadherin defines quiescent, committed precursors and speculate that the CD34 Ϫ ve , Myf5 Ϫ ve minority may be involved in maintaining the lineage-committed majority.

Purpose -This study was designed to extend knowledge of cognitive processing of country of origin cues by refining the concept of country image and investigating its role in product evaluations. Design/methodology/approach -Data were collected from residents of a large North American metropolitan. A total of 436 usable questionnaires were returned. Data analysis was conducted using the EQS structural equation modeling software Findings -We found that country image is a three-dimensional concept consisting of cognitive, affective, and conative components. We modeled the relationships among country image, product beliefs, and product evaluations, and found that country image and product beliefs affect product evaluations simultaneously regardless of consumers' level of familiarity with a country's products. Findings also indicated that the structure of country image influences product evaluations both directly and indirectly through product beliefs. Consistent with affect transfer theory, the results showed that when a country's image has a strong affective component, its direct influence on product evaluations is stronger than its influence on product beliefs. Alternatively, when a country's image has a strong cognitive component, its direct influence on product evaluations was smaller than its influence on product beliefs. Research limitations/implications -One limitation pertains to the relatively poor psychometric properties of some items. Future research will benefit from further improvements in the measures of country image that tap into the various facets of the construct. Originality/value -The major contributions of the study consist of the full operationalization of country image as a three-dimensional concept, and the findings on the impact of country image structure on consumers' evaluation processes.