Cellular Packing Research Articles

Stereological quantification of histological parameters in turpentine-induced hyperplasia of hamster cheek pouch epithelium

Epithelial hyperplasia was induced by regular painting with 50 per cent v/v turpentine in liquid paraffin. Point and intersect counting were used to analyse representative microscope fields photographed on black and white reversal film and examined on a back projector at a × 900 magnification. Nuclear-cytoplasmic ratio, nuclear and cellular packing density, nuclear and cell volume, epithelial thickness, epithelial volume, and volume to interface ratios of epithelium were estimated. Corrected numbers of nuclei and cells were derived using factors which made allowances for section thickness and nuclear size and assumed the nuclei to be approximately spherical. The results showed that both hypertrophy and hyperplasia occur in turpentine-treated hamster cheek pouch epithelium. At the histological level stereological techniques can be employed to detect quantitative similarities and differences between normal and pathological epithelium.

Stereological quantification of histological parameters in normal hamster cheek pouch epithelium

A stereological investigation was performed on histological sections of normal epithelium obtained from both cheek pouches of 5 hamsters. Point and intercept counting techniques were used to analyse representative microscope fields photographed on black and white reversal film and examined in a back projector at a viewing magnification of × 900. Cytological and histological parameters of defined epithelial components were estimated, including nuclear-cytoplasmic ratio, nuclear and cellular packing density, nuclear and cell volumes, epithelial thickness, epithelial volume and “volume to interface ratios” of epithelium. Epithelial thickness was also measured directly using a calibrated micrometer eyepiece. Numbers of nuclei and cells were obtained using correction factors which made allowances for section thickness and particle size and assumed the particles to be approximately spherical in shape. The results showed that it was possible to estimate some specific epithelial parameters stereologically at light microscope level.

Ontogeny of monoamine neurons in the locus coeruleus, raphe nuclei and substantia nigra of the rat

Synaptogenesis was studied in the monoamine (MA) cell groups locus coeruleus (LC), dorsal and medial raphe nuclei (RN) and substantia nigra, zona compacta (SN) between day 18 of gestation and postnatal day 60 using ethanolic phosphotungstic acid (E-PTA) to visualize synaptic profiles. Nuclear area, and cellular packing density (inversely proportional to area of neuropil) were also determined. As determined using the E-PTA method, synaptogenesis begins in the neuropil of the SN first, on or before 18 days of gestation, and in the LC and RN at 19 days. Synaptogenesis on MA cell perikarya is first observed in the SN, on or before 18 days, and in the LC and RN at 20 days. The onset of somatic synaptogenesis coincides with the beginning of nuclear growth and development of the neuropil (decrease in cellular packing density) in all MA cell areas, raising the possibility of common factors in the initiation of these processes. Nonsynaptic contacts precede the appearance of synaptic profiles both in the neuropil and on the somata of the MA cells of the LC, RN and SN, and may represent precursors of mature synapses or desmosome-like contacts. Somatosomatic nonsynaptic contacts occur only prenatally between adjacent MA neurons in the LC, RN and SN. Although some synaptogenesis occurs prenatally in these MA cell groups (indiciating that these parts of the MA circuitry may be functional before birth), most of this synaptogenesis occurs postnatally and continues into adulthood. Since such synaptogenesis does not begin until 2-4 days prior to birth, whereas these neurons and their processes exhibit MA fluorescence as early as 12-14 days of gestation, they apparently are capable of synthesizing transmitter and proliferating terminals before they themselves are innervated.

Stereological description of the anterior horn cervical cord of the adult rat. A quantitative study using the optical microscope.

AbstractThe histometric properties of the most ventral, ventromedial and ventrolateral zones in the anterior horn of adult rat cervical enlargement were studied by quantitative optical microscopy. The spinal cord areas were identified in semi‐thin Araldite sections and unbiased samples of the test tissue were recorded on photomicrographs. By defining the tissue on the basis of a histometric model, it was possible to describe a number of important stereological parameters including compartmental volume proportions, cellular packing densities, perikaryal volumes and surface areas, and blood vessel length per unit volume.It was established that each cubic milimetre of tissue consists of approximately 0.85 mm3 of neuropil, 0.04 mm3 of blood vessels, 0.02 mm3 of neuroglial cells, 0.08 mm3 of motoneuron perikarya and 0.02 mm3 of small neuron perikarya. Roughly 0.11 mm3 of the neuropil compartment can be attributed to myelin. Estimates of cell body packing densities revealed an average of 44,950 neuroglial cells and 11,650 neurons per mm3. Small and motor neurons occur in approximately equal numbers. The average motoneuron has a perikaryal volume of 12,100 μm3 and a perikaryal surface area of 2,500 μm2. Corresponding figures for small neurons are 2,200 μm3 and 650 μm2. The average glial cell soma has a volume of 370 μm3. Differences between the nuclear volume proportions and nuclear size distributions of glial cells, small neurons and motoneurons are also reported. Each mm3 of tissue contains 1.2 metres of blood vessels, of average diameter 6.4 μm and with an outer surface area of 21 mm2.The results are presented and discussed in the context of data published by workers in other laboratories.

Efficiency of cellular packings for vacuum mass-transfer columns

Efficiency of cellular packings for vacuum mass-transfer columns