The size of the thymus usually peaks during adolescence, and atrophies in the following decades. The male then atrophies into nothing more than a pair of gonads. When occlusal forces are reduced the PDL atrophies, appearing thinned. In myeloid leukemia, the white pulp atrophies and the red pulp expands. Its trunk atrophies and is replaced by branches from the external carotid artery. DSMA1 was identified and classified as a sub-group of spinal muscular atrophies (SMA) in 1974. Neuromophology has been used to study optical nerve damage, specifically looking at lesions and atrophies. The vocalis muscle atrophies in both men and women. It atrophies after about six months. The media reacted to the charge that comprehensive schools are "the place where intelligence atrophies".