Morphometry of the renal corpuscle during normal postnatal growth and compensatory hypertrophy. A light microscope study.

Renal corpuscles from the juxtamedullary and subcapsular regions of the renal cortex were morphometrically analyzed in young rats and in adult rats that had been unilaterally nephrectomized or sham-operated at an early age. Mean corpuscular volumes increased 4.5-fold during normal development, and 7.7-fold as a result of compensatory hypertrophy in both cortical regions. Relative and absolute volumes were determined for Bowman's space, the glomerular tuft, and five glomerular components: epithelial, endothelial, and mesangial cells, capillaries, and the filtration membrane. Normal and hypertrophic enlargement of Bowman's space was slightly greater than glomerular growth, and the growth response of subcapsular glomeruli was greater than that of juxtamedullary glomeruli. The ratio of mean glomerular volumes between outer and inner glomeruli was 1:2 in both adult groups. Both adult groups also developed nearly identical proportions of all glomerular component structures, representing a relative decrease of epithelial cells and increase of capillaries compared to the young animals. Normal and hypertrophic maturation involved absolute increases in all glomerular cell populations, the length of capillary loops and the surface area of the filtration membrane, all nearly in proportion to the respective four- and seven-fold increases in glomerular volume. Changes in the filtration surface area are consistent with published data for glomerular filtration rates in normal and hypertrophied kidneys. The mean cell size in epithelial and mesangial populations doubled during growth, but was not greater than normal in mononephrectomized rats. Hyperplasia among all populations of glomerular cells is indicated in normal growth, and to a greater extent in compensatory renal hypertrophy.

[A case of epidermodysplasia verruciformis with neoplastic degeneration and demonstration of viral particles in warts (author's transl)]. / Caso di epidermodisplasia verruciforme con degenerazione neoplastica d dimostrazione di un virus nelle lesioni verrucose

A case of epidermodysplasia verruciformis, already described by Borelli in 1946, was presented. The electron microscopy showed viral intranuclear particles in the verrucous lesions. A Bowen-like tumor was found on the forehead. The connections are described between virus and tumor.

Morphometry and autoradiography of early hypertrophic changes in the ventricular myocardium of adult rat: an electron microscopic study.

The ultrastructural composition of left ventricular myocardium and myocytes has been investigated at 20 hours after the surgical production of a subdiaphragmatic aortic stenosis in the adult rat. Morphometric analysis shows a 20% increase in the size of myocytes resulting principally from a 36% increase in mitochondrial volume and a 78% increase in the volumes occupied by smooth endoplasmic reticulum and matrix. Myofibrillar volume is increased only 4%. Measurements of the size and shape of individual mitochondria indicate that the augmentation of this compartment is wholly accountable by the enlargement of preexisting mitochondria. Quantitative autoradiographic analysis following a 2-hour pulse labeling with 3H-leucine shows that the rate of incorporation of newly synthesized proteins is practically uniform throughout all structural components of the sarcoplasm 18 to 20 hours after aortic banding. The conclusion is reached that this interval of hypertrophic response is a transition period characterized by an increasing rate of synthesis of contractile proteins overtaking a previously greater rate of mitochondrial synthesis.

Morphometric and autoradiographic study of developing ventricular and atrial myocardium in fetal rats.

The ventricular and atrial myocardia of 19- to 21-day-old rat fetuses have been studied by electron microscopic morphometry and quantitative autoradiography following the injection of 3H-leucine. The myocytes in both these regions contain numerous myofibrils located predominantly near the sarcolemma and oriented parallel to each other and to the long axis of the cell. The width of myofibrils at this stage of development is 0.428 +/- 0.240 mum. in the ventricle and 0.365 +/- 0.185 mum. in the atrium. The volume fractions of myofibrils, mitochondria, smooth endoplasmic reticulum, sarcoplasmic matrix, and sarcolemma in ventricular myocytes are nearly equal to the corresponding fractions in atrial cells. A similarity between ventricular and atrial myocytes was also found in the distribution of newly synthesized proteins as indicated autoradiographically by the concentration of grains over various sarcoplasmic structures. In both tissues the concentration of grains was consistently above average over the sarcolemma, smooth endoplasmic reticulum, and myofibrils; average over the mitochondria; and below average in association with the sarcoplasmic matrix. The specificity of this autoradiographic procedure for labeled amino acids actually incorporated into protein was tested biochemically, and it was found that glutaraldehyde-paraformaldehyde fixation leads to a negligible contamination with non-specifically bound leucine. It is suggested that the high concentration of protein labeling near the sarcolemma is related to the imminent development of the T-system and its associated channels of sarcoplasmic reticulum.

Morphometry and autoradiography of early hypertrophic changes in the ventricular myocardium of adult rat. A light microscopic study.

Quantitative autoradiographic localization of newly synthesized proteins was studied in the ventricular myocardium of adult rats 2 hours after the intravenous injection of 3H-leucine and 20 hours after the induction of hypertrophy by constriction of the abdominal aorta. Equal area samples of tissue from experimental and sham-operated controls were examined for differential grain counts and morphometric measurements by light microscopy. In comparison with control levels, the hypertrophic hearts show a 20 per cent increase in the average cross-sectional area of myocytes and a 43 per cent increase in the incorporation of amino acid into proteins. The higher concentration of labeled proteins is confined mainly to cardiac muscle cells, which show a 90 per cent increase in grain counts per cell cross-section, whereas no significant change is observed over the interstitium. A test of the specificity of the autoradiographic technique shows the expected reduction in tissue labeling following cycloheximide inhibition of protein synthesis, indicating that there is no significant amount of nonspecific binding of free amino acid during the paraformaldehyde-glutaraldehyde fixation procedure.