Ciliary granule plaques: membrane-intercalated particle aggregates associated with Ca2+-binding sites in paramecium.

In Paramecium nine rectangular aggregates of membrane-intercalated particles surround the freeze-cleaved membrane of the ciliary base. These "ciliary granule plaques" occur independently of the "ciliary necklace" which is observed in a more basal position on some cilia. In each individual plaque the approximately 10 nm large granules are arranged in a square grid pattern: the granules of one plaque invariably form 3 vertical rows (number of horizontally arranged particles per row: Nh = 3) and 3-6 horizontal rows (mean value fos intrahepatic tributaries then can be approached under direct vision in a relatively bloodless field for safe, accurate liquation and/or reconstruction.