| The pancreatic beta cell population appears to be relatively dynamic, capable of regulating its size in response to a number of intrinsic and environmental factors. Although absolute quantification of the beta cell population is desirable for many experimental systems, relatively few studies attempt to do so. Traditional morphometrical and stereometrical methods for enumerating cells within a solid organ are labor-intensive and require complex and rigorous methodologies for sampling and counting. I present an alternative method for counting beta cells that avoids issues of random sampling and identity assignment by dissociating the tissue to single cells and counting immunofluorescently stained cells by flow cytometry.; The pancreatic beta cell population increases during adult life in rodents. This growth has been reported to be linearly related to body weight growth, suggesting that body weight or a closely related variable is the benchmark by which the beta cell population is regulated. I have examined the number of beta cells in the female ICR mouse, a strain prone to spontaneous obesity in later life, at ages from 2 days to 14 months, or over the majority of the expected lifespan, using the counting method I developed. I find that, although there seems to be a linear relationship between the beta cell number and body weight in younger adults, in older, obese adults there is a marked increase in both the absolute and the proportional number of beta cells. This may indicate that body fat is part of a second, possibly independent pathway for beta cell regulation. |
