Our images revealed that ungerminated C. sporogenes spores
had one of two terminal structures at one end of the exosporium;
either an aperture (Fig. 2a) of 0.3e0.4 mm at its widest point or a
lipped terminal protrusion termed here a sporiduct (Fig. 2b and c).
The fraction of C. sporogenes spores exhibiting a hole or sporiduct in
the exosporium could not be reliably estimated due to spore
orientation. Although the significance of the spore having a sporiduct
as opposed to an aperture is unknown, we can only hypothesize
that the sporiduct could be a relatively weak structure and
removed during spore preparation to leave an aperture. The sporiduct
structure itself had a loose or flaccid appearance with a lipped