analysis of the 1012 chromosomes in 22 zygotene and pachytene spermatocyte nuclei showed that in most of the cells that reached the pachytene stage , one or more of the following abnormalities were found in the intranuclear structures : decreased condensation of euchromatin , centromeric heterochromatin , diffuse heterochromatin , or abnormal nucleolar morphology .
C0007610
nuclei
C0019397
heterochromatin