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Fig. 3. Three steps in the modeling process applied to the secretory canaliculi of
a parietal cell. (A) A single thin section from a series of 30 consecutive
serial sections from a specific intracellular region. In this section two
canaliculi are outlined (blue) to form one set of contours defining the
canalicular surface (exclusive of microvilli, which project into the lumens of
the canaliculi). Bar marker is 1 µm. (B) A series of consecutive
canalicular contours traced from 29 serial sections as shown in (A) (one
contour was not included in the data set owing to a fold in the section). (C)
Meshed model of three canaliculi from contours shown in (A) and (B).
Interconnections can be seen between two of the canaliculi in some planes.
Morphological complexity made it difficult to follow the exact outline of the
entire canalicular surface including each microvillar extension, so this model
was constructed using only the surface that outlined the canaliculus at the
base of the microvilli.