Determination Of Cell Size Research Articles

Determination of mean cell size of Tetrahymena in growing cultures.

SUMMARY: The changes in volume, measured by a Coulter particle counter (the ‘electronic volume‘), when suspensions of Tetrahymena are diluted with aqueous electrolyte have been examined kinetically. The diluting solution can have an optimal colligative concentration in which there is initially no change of the measurement; in suboptimal concentration there is initial increase followed by a decrease to a value somewhat less than that prevailing at the moment of dilution (95%), whereas in superoptimal concentrations there is initial decrease followed by an increase. If the initial decrease is severe the subsequent increase restores the value to only 80% of the original. The measurements of electronic volume, and of its changes, reflect the corresponding mean cell volume, and changes of it, estimated by photographic methods. The changes can be accounted for by changes of balance between the elasticity of the cell walls and the osmotic pressure across the walls.

Microscopic fat cellsize measurements on frozen-cut adipose tissue in comparison with automatic determinations of osmium-fixed fat cells

Diameters of fat cells in adipose tissue slices, floating in an isoosmolar solution, were measured under a microscope. The slices were obtained from percutaneous biopsies by freeze-cutting after brief formaldehyde fixation. All cells in a given part of the slice were measured, thus avoiding selection. A normal distribution of fat cell diameters could be demonstrated with this method, as has been found with previously described methods. The error of the method was 2.6% for diameter and 8.0% for weight determinations. Storage of adipose tissue at 4 degrees C for 48 hr had no effects on cell size determinations. Results with this microscopic method were compared with those obtained from a previously described method for automatic determinations of osmium-fixed fat cells. The latter method was slightly modified by using a viscous electrolyte, which prevented sedimentation of large fat cells, and by using sonication to complete cell separation. The methods agreed closely. A method for calculating mean fat cell weight using osmium-fixed fat cells is described, which makes determinations of sample wet weight and ratio of lipid to wet weight unnecessary.

Methods for the determination of adipose cell size in man and animals

Four methods for the sizing of adipose cells in small samples of human or animal adipose tissue are compared. These methods depend on the preparation of cell suspensions by incubation of the tissue with collagenase or by prolonged fixation with osmium tetroxide and separation of the fixed cells. A Coulter electronic counter was used to count and size the suspended cells and a Zeiss particle size analyzer for the sizing of cells in photomicrographs. The use of the Coulter counter to count cells in a suspension derived from a known amount of tissue and subjected to osmium tetroxide fixation is recommended for accuracy and general applicability to adipose cells of all sizes in man and animals.

A KINETIC STUDY OF THE MYENTERIC NEURONES: SIZE VARIATIONS IN THE NEUROVEGETATIVE PERIPHERY WITH BODY WEIGHT AND ORGAN SIZE.

AbstractThe relationship between organ size, body weight and the size variations in myenteric neurones of the ileum and cecum has been studied in white Fisher rats. Three groups of conventional as well as germfree rats of varying body weight were utilized.Myenteric neurones in the cecum and ileum “grow” with increasing body weight. Cecal neurones have a steeper growth curve than ileal neurones. The average diameter of Auerbach's ganglion cells in the cecum is 13.6 μ in 90 gm rats, 20.0 in 300 gm rats. In medium sized rats (150 gm) the myenteric neurones of the germfree cecum are 2–3 times as large as those in the cecum of conventional animals. This increase is proportional to the enlarged cecal circumference in germfree rodents. When small (90 gm) germfree rats are conventionalized the myenteric neurones return to normal size as the cecum “shrinks” to normal size. In the intramural parasympathetic nervous system of the gut organ size as well as body weight are determinants of ganglion cell size.

Automatic cell-size determination and orientation of single crystals

Automatic cell-size determination and orientation of single crystals

The effect in vitro of estrone and bradykinin on a nuclear abnormality in a hamster ascites tumor

Bradykinin caused a decrease in the number of polynucleated cells only in the presence of estrogens. Bradykinin may influence cell permeability to estrogens, and estrogens may be the active factor instead of bradykinin. However, when bradykinin, estrone, and washed polynucleated cells were incubated in vitro, decrease in polynucleated cell numbers did not occur until after 2 hr. Incubation of bradykinin and estrone for 4 hr before addition of washed polynucleated cells resulted in decreased numbers of polynucleated cells in less than 2 hr. This suggests that bradykinin and estrone form a complex or third product which is the active agent and that the phenomenon may not be explained entirely on the basis of altered cell permeability to estrogens. Effect of agents upon polynucleated tumor cells has been determined by microscopic counts of polynucleated cells before and after incubation. Evidence indicated that reduction in the number of polynucleated cells was the result of cytokinesis occurring around each nucleus in a polynucleated cell. This resulted in an increased number of small tumor cells in the culture. Use of the Coulter particle-size distribution plotter to determine cell size shifts and increased numbers of smaller tumor cells after incubation with bradykinin and estrone offered a simple objective method to replace the laborious and subjective microscopic determination of polynucleated cell numbers.

Role of the Y-Chromosome in the Determination of Cell-size in D. melanogaster

I have already pointed out1 that in wild stocks of D. melanogaster, Gaiano (Parma), Luino (Varese), Civate (Como), the unicellular hairs of the upper wing surface, counted in a standard surface of 298 µ2 for each wing, show frequency differences. Furthermore, there are sex differences of different kinds in the three stocks, being highest in Gaiano, intermediate in Civate and lowest in Luino. This shows the possibility of an action of the Y-chromosome, already proved by Mather2 for the chaetae also in D. melanogaster.