Table 4. Comparison of fiber anterior, middle, and posterior segment lengths

Although fibers are not physically segmented along their length, it is not inaccurate to describe fibers as segmented because of variations in fiber structure along fiber length. The anterior segment of a fiber is that end portion of a fiber that curves away from the polar axis to become a component of an anterior suture branch (see Figure 2). The middle segment of a fiber is that portion of a fiber that is aligned parallel to the polar axis. The middle segment of a fiber is not directly involved in suture branch formation. The posterior segment of a fiber is that end portion of a fiber that curves away from the polar axis in the opposite direction than the anterior segment, to become a component of a posterior suture branch. While the length of anterior and posterior fiber end segments vary as a function of a fiber's proximity to the origin and termination of its suture branches, fiber middle segment length does not vary between fibers of a growth shell (see Figure 14). The range of fiber segment length (individual segment length/total fiber length times 100) in a representative growth shell was calculated using the Mensuration formulas described in Table 2.

                                      Middle
          Anterior      Segment      posterior
           segment    (equatorial)    segment
Species    length        length       length
-------   ---------   ------------   ---------
Frog        0-32%        61-74%        0-27%
          0-1.45 mm      2.95 mm     0-1.11 mm

Rabbit      0-33%        62-75%        0-25%
          0-4.86 mm      9.79 mm     0-3.44 mm

Mouse       0-33%        62-72%        0-28%
          0-1.01 mm      2.06 mm     0-0.82 mm

Bovine      0-32%         63-73%       0-27%
          0-6.89 mm     14.28 mm     0-5.16 mm