Morphological and morphometric study of early changes in the ageing golden hamster testis

The histological and morphometric features of the aged golden hamster testis were examined and compared with those of adult animals. Three age groups (6, 12 and 18 months) were studied by light microscopy, and testosterone levels were determined. The observations showed a progressive involution of the seminiferous tubules, beginning to be perceptible at 12 months with slight hypospermatogenesis and desquamation. In 18-month-old specimens degeneration was more significant and histopathological lesions could be classified on a 6-point scale, ranging from slight hypospermatogenesis to absence of germ cells. These involutive changes were not homogeneously distributed in the testis; affected tubules close to seeming normal ones were present. The morphometric results point to a progressive diminution, in the 3 age groups, in vas deferens spermatozoa, pachytene spermatocytes, and Sertoli and Leydig cells (the latter significantly diminished only in the 18-month-old group). For morphometric purposes a 7-point scale of tubule degeneration was used, showing a significant increase, with age, in the presence of more degenerated tubule stages. Several correlations were found between the morphometric variables, outlining existing relations between age and the associated diminution of several testis cell types, and lumen diameter. No significant differences were found between groups in serum testosterone levels. In conclusion, histological changes related to age are evident in 18-month-old animals, while at 12 months a diminution in germ cell numbers and sperm production is detectable.