Fewer Sperm in the Summer

Abstract

During the past two decades, we have become increasingly knowledgeable about human spermatogenesis, its physiologic control, methods of altering it, and the pathologic factors that impair it. We remain ignorant, nonetheless, about many factors that influence spermatogenesis. The paper by Levine et al.¹ in this issue of the Journal about seasonal variability in sperm production provides interesting new infbrmation on the subject, although many questions still remain unanswered.Spermatogenesis occurs within the seminiferous tubules of the testes. Testosterone is secreted by the Leydig cells, which reside in the interstitium among the tubules, and its secretion is stimulated by luteinizing hormone . . .