THE INFLUENCE OF OVERCROWDING ON SPERMATOGENESIS, SIZE OF LEYDIG-CELL NUCLEI (HISTOMETRICAL INVESTIGATION), AND THE ADRENAL CORTICOSTERONE CONTENTS IN MICE

Abstract

ABSTRACT Adult male NMRI-mice were kept alone or in groups of 5, 10, 20, 30, 40 and 60 animals for 28 days and were then sacrificed. The corticosterone levels of their adrenals were determined and their testes were examined histometrically. The corticosterone levels of the adrenals increased two-fold with increasing population size. Furthermore the increased population size caused a suppression of some testicular functions: the seminiferous tubules decreased up to 20 % and the relative frequency of the spermatids up to 10 % whereas the numbers of spermatocytes and spermatogonias increased correspondingly. A decrease of about 25 % of the testosterone dependent postmeiotic stages of spermatogenesis is assumed. Since the diameters of the Leydig-cell nuclei decreased about 20 %, a reduction of the testicular testosterone secretion can be projected. All measurements proved the group with 5 animals to be the most favourable group size.