Pollen cell. In flowering plants the vegetative tube cell produces the pollen tube, and the generative cell divides to form the two sperm cells. Pollen is produced in the microsporangia in the male cone of a conifer or other gymnosperm or in the anthers of an angiosperm flower. Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see electron micrograph, right). Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the forget-me-not ("Myosotis" spp.), is around 6 µm (0.006 mm) in diameter. Wind-borne pollen grains can be
Shroud of Turin should be suspended until a new collection of pollen grains can be carried out and the grains thus obtained can be studied with modern equipment and by an expert of pollen of this area." Skeptics have argued that the flower images are too faint for Danin's determination to be definite, that an independent review of the pollen strands showed that one strand out of the 26 provided contained significantly more pollen than the others, perhaps pointing to deliberate contamination. Skeptics also argue that Max Frei had previously been duped in his examination of the Hitler Diaries and that he may