Figure 6
From: Computational analyses decipher the primordial folding coding the 3D structure of the beetle horn
Various folding methods were employed in the biological 3D origami of the beetle horn. Transformation from horn primordium to pupal horn occurs within 2 h in vivo. During it, the folding of the horn primordium did not expand the entire primordium uniformly; different folding patterns in different positions contributed to the change of shape in different ways. The furrows in the base, whose distribution is biased to the ventral side, turn the orientation of the horn dorsally. In the cap, furrows have specific patterns, such as concentric semicircles and parallel straight patterns. These 2D patterns actively shaped the distal four-branched structure. On the other hand, the folding in the stalk showed features suggestive of passive formation. Wavy and zigzag folding may be formed by the bending force and longitudinal compression, respectively. Together, active furrows generating a specific shape and passive folding without generating any shape (essentially plane) are employed in combination to form the complex pupal horn shape.
