Rules of tissue packing involving different cell types: human muscle organization

TLDR

Natural packed tissues, such as skeletal muscle, form tessellations of polygonal cells, with muscles composed of slow and fast fibers whose relative distribution influences function, yet the mechanisms establishing this arrangement remain unclear. The study aims to capture the organizational pattern in two healthy muscles, biceps brachii and quadriceps. The authors analyze the spatial arrangement of slow and fast fibers in these muscles to understand how cell size differences drive tissue tessellation. The biceps brachii displays a distinct arrangement driven by size differences between slow and fast fibers, whereas the quadriceps shows an unbiased distribution, indicating that relative cell size imposes intrinsic organization in natural tessellations and providing a framework for analyzing packed tissues with multiple cell types.

Abstract

Abstract Natural packed tissues are assembled as tessellations of polygonal cells. These include skeletal muscles and epithelial sheets. Skeletal muscles appear as a mosaic composed of two different types of cells: the “slow” and “fast” fibres. Their relative distribution is important for the muscle function but little is known about how the fibre arrangement is established and maintained. In this work we capture the organizational pattern in two different healthy muscles: biceps brachii and quadriceps. Here we show that the biceps brachii muscle presents a particular arrangement, based on the different sizes of slow and fast fibres. By contrast, in the quadriceps muscle an unbiased distribution exists. Our results indicate that the relative size of each cellular type imposes an intrinsic organization into natural tessellations. These findings establish a new framework for the analysis of any packed tissue where two or more cell types exist.