The weight of the thymus gland in a population of wild Bank voles, Clethrionomys glareolus, from Wicken Fen, Cambridgeshire



Changes in the thymus weights of a population of wild Bank voles were studied from four-weekly samples taken over a 4-year period in an area of fenland. By considering physiological state it is possible to distinguish first year young from older individuals and to correlate the changes in thymus size with stages in the reproductive cycle.