Quantitative ultrastructural approach to the study of the spatial relationships among cell organelles. I. Cytological organization of human exocrine epithelia.

Currently available morphometric methods provide useful information on the three-dimensional properties (such as volume, surface, etc.) of biological structures. These methods, however, do not reveal how the same structures are spatially organized within the cell. A sum of problems, which concern mainly the definition of shape and location of the sectioned structures, does not allow the three-dimensional representation of the organelle arrangement from a quantitative analysis of sections. Following a different approach, this study considers the topographic relationship between ten distinct subcellular structures: nucleus, Golgi, ribosomes, mitochondria, lysosomes, lipid droplets, secretory granules, and apical, lateral, and basal plasmalemma. The analysis of associations from 2 X 2 tables calculated for each pair of structures and the pattern of multiple associations obtained by clustering methods provide a useful description of the spatial relationship among different cell compartments. The results of the investigation carried out in parallel on seven human exocrine glands (pancreas, parotid gland, submandibular gland, lacrimal gland, ceruminous gland, ampulla of the vas deferens, and seminal vesicle) allow an immediate evaluation of the method and a comparative analysis of the cytologic organization of secreting cells of human exocrine glands.