P-protein distribution in mature sieve elements of Cucurbita maxima

  title={P-protein distribution in mature sieve elements of Cucurbita maxima},
  author={Ray F. Evert and Walter Eschrich and Susan E. Eichhorn},
Portions of the hypocotyls of 16-day-old Cucurbita maxima plants, from which the cotyledons and first foliage leaves had been removed 2 days earlier, were fixed in glutaraldehyde and postfixed in osmium tetroxide for electron microscopy. In well over 90% of the mature sieve elements examined the P-protein was entirely parietal in distribution in both the lumina and sieve-plate pores. In addition to the parietal P-protein, the unoccluded sieve-plate pores were lined by narrow callose cylinders… CONTINUE READING