Stereological Model Research Articles

Ultrastructural morphometric analysis of the unstimulated adrenal cortex of rats

A stereological model providing information on the structure of the nonstimulated adrenal cortex has been developed for the rat. The model consists of morphologically defined space and membrane compartments which were used to describe the zonation of the adrenal cortex and the specific compartments of the steroid-synthesizing adrenocortical cells. The results presented are relative to 1 cm3 of adrenocortical tissue, 1 cm3 of zonal adrenocortical tissue, 1 cm3 of zonal adrenocortical cell cytoplasm, and the volume of an average adrenocortical cell. The adrenal cortex consisted of 10% zona glomerulosa, 63.5% zona fasciculata, and 26.5% zona reticularis. In the cells of the zona fasciculata the compartments occupied the following relative amounts of space: 14.3% nucleus, 38.4% ground cytoplasm, 7.1% smooth endoplasmic reticulum, 31.7% mitochondria, 7.1% fat droplets, and 0.7% lysosomes (0.7% extracellular space). The volume density of the mitochondria and the surface density of the mitochondrial inner membrane of the zona fasciculata are significantly higher than in the other two zones. The volume and surface values of the smooth endoplasmic reticulum showed no significant differences. The application of this model to the study of the stimulated adrenal cortex is discussed. Therefore, special attention was given to the cell compartments involved in steroid synthesis.

Stereological analysis of the guinea pig pancreas. I. Analytical model and quantitative description of nonstimulated pancreatic exocrine cells.

A stereological model which provides detailed quantitative information on the structure of the fasted, nonstimulated gland has been developed for the guinea pig pancreas. The model consists of morphologically defined space and membrane compartments which were used to describe the general composition of the tissue and the specific components of exocrine cells. The results are presented, where appropriate, relative to a cubic centimeter of pancreas, a cubic centimeter of exocrine cell cytoplasm, and to the volume of an average exocrine cell. The exocrine cells, accounting for 82% of the pancreas volume, consisted of 54% cytoplasmic matrix, 22% rough-surfaced endoplasmic reticulum (RER), 8.3% nuclei, 8.1% mitochondria, 6.4% zymogen granules, and 0.7% condensing vacuoles. Their total membrane surface area was distributed as follows: 60% RER, 21% mitochondria, 9.9% Golgi apparatus, 4.8% plasma membranes, 2.6% zymogen granules, 1.8% plasma membrane vesicles, and 0.4% condensing vacuoles. The application of this model to the study of membrane movements associated with the secretory process is discussed within the framework of an analytical approach.

A stereologic model of pneumotaxic oscillator based on spatial and temporal distributions of neuronal bursts.

A stereologic model of pneumotaxic oscillator based on spatial and temporal distributions of neuronal bursts.