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**Chapter 8**

**Abstract**

marbling.

**1. Introduction**

**2. Marbling**

Dystrophy

Interspecies Translation: Bovine

There are interesting similarities and differences when comparing the histopathology of bovine marbling and human muscular dystrophy. At the simplest level, both conditions are characterized by genetically controlled and more or less inexorable replacement of muscle fibers with fat cells. At issue is whether an improved understanding of these two processes can lead to better outcomes for patients. There are many forms of dystrophy that differ in their genetics and their histopathology. There are also many forms of "marbling" ranging from the coarse to fine, epimysial, perimysial to endomysial and even to total replacement or steatosis. A detailed examination of marbling will provide a framework for further investigation of human dystrophy. Ultimately, the many genetic factors involved can be addressed through a better understanding of the metabolic pathways involved in

Marbling to Human Muscular

*Jose L. Valenzuela, Sally S. Lloyd, Edward J. Steele,* 

**Keywords:** synteny, muscular dystrophy, bovine marbling, adipogenesis

The purpose of this review is to compare the genetics and histopathology of bovine marbling and human muscular dystrophy. Surprisingly, in spite of similarities, the literature suggests that marbling is a function of extreme adipogenesis whereas dystrophy is a consequence of fundamental defects in muscle itself. In fact, completely independent studies, as summarized here, reveal that similar genes have been implicated in some selected situations. Further, it is clear that the histopathology of some forms of dystrophy can resemble some forms of bovine marbling.

Marbling is the term used to describe the presence of macroscopically visible fat within muscle (**Figures 1** and **2**). Coarse marbling refers to white areas of fat through and around muscle bundles, generally as continuous bands arising from the subcutaneous adipose tissue. By contrast, fine or "snowflake" marbling is character-

ized by more even white flecks resulting in pink rather than red muscle.

*Francis L. Mastaglia and Roger L. Dawkins*
