The ultrastructure of ciliary muscle was studied in an old, healthy crabeating monkey. In the cytoplasm, large swollen mitochondria, interdigitated mitochondria, various types of myelin-like figures, dense coarse membranous structures, lysosomal dense bodies, round lipid-like bodies, transitional forms from lysosomal dense bodies to lipid-like bodies, lipofuscin pigments, whorl-like structures ...