Adrenal glands of mice and rats: A comparative morphometric study

Mice and rats are among the most used laboratory animals. They share numerous similarities along with differences, some yet unexplored. One of them is the morphometry of their adrenal glands, whose characteristics may be related to differences in energy management, immune response, drug metabolism, behaviour and temperament. The present study tries to fill this knowledge gap with the evaluation and comparison of adrenal gland anatomical/morphometric parameters of mice and rats. In groups of 10 (n = 10) adult, male and female BALB/c mice and Wistar rats, one in every 20 sections transverse to the longitudinal axis of the gland was used for measuring entire gland area, capsule, entire cortex, cortex zones and medulla with the aid of an image analysis system and subjected to statistical analysis. Quotients of the individual areas were calculated and comparison between the resulting ratios was performed. Gland length and volume were also calculated. Statistically significant differences were revealed between the rat female and male cortex area, rat and mouse medulla/cortex, medulla/gland, zona glomerulosa/cortex and cortex/gland ratios, male and female rats' medulla/cortex, medulla/gland, capsule/gland, zona glomerulosa/cortex, zona reticularis/cortex and zona glomerulosa/zona fasciculata ratios, length and volume. The correlation evaluation revealed that in male rats and in female mice the larger medulla area was accompanied by a larger cortex area and vice versa. In general, a larger cortex area was accompanied by larger areas of cortex zones. The collected data and the revealed differences can possibly contribute to the understanding of the physiology of the two species.