Pm. Wigmore et al., AFTER EMBRYONIC DAY 17, DISTRIBUTION OF CELLS ON SURFACE OF PRIMARY MUSCLE-FIBERS IN MOUSE IS NONRANDOM, Developmental dynamics, 207(2), 1996, pp. 215-221
During the formation of skeletal muscle, secondary fibres form, by cel
l fusion, on the surface of primary fibres, Three-dimensional reconstr
uctions of primary fibres with the secondary fibres and cells on their
surfaces were produced from spaced serial transmission electron micro
graphs, Reconstructions were made of fibres from embryonic day (E) 17,
E19, and E21 of the Extensor Digitorum muscle of Balb/c mice. Cell di
stribution was analysed in two ways, Firstly, nearest neighbour analys
is was used to see if cells were randomly arranged or clustered, Secon
dly, the association of cells and secondary fibres was tested by measu
ring the distances between cells and each secondary fibre. Cells were
found to be randomly distributed on the surface of primaries at E17 bu
t significantly clustered, and associated with smaller secondary fibre
s at E19 and E21, Cells were not associated with the ends of secondary
fibres, Cells associated with secondary fibres lay in the groove form
ed by contact between adjacent primary and secondary fibres, This appa
rent response to the topography of the surface on which the cells are
lying has previously been mimicked in vitro by growing cells on groove
d surfaces, It is likely that cells associated with secondaries will f
use laterally with these fibres and their response to topography is pa
rt of the process of bringing them into correct alignment with the fib
re before fusion. (C) 1996 Wiley-Liss, Inc.