Unique intertesticular tissue complex in larvae of Heliothis virescens (F.) (Lepidoptera : Noctuidae)

Abstract

A unique heart-testis complex has been found in the last instar of the tobacco budworm, Heliothis virescens (F.) (Lepidoptera : Noctuidae). This complex consists of a previously undescribed muscle system, herein designated the cardiotesticular muscle, that attaches the heart to the testes, and a ubiquitous connective tissue sheath that overlays this muscle and surrounding fat body and pericardial cells. These interconnected organs form a sieve-like septum enclosing a sinus that contains clusters of hemocytes and lipid droplets. Lipid droplets appear to be released from the surface of the testes sheath. The cardiotesticular muscle is innervated by neuroendocrine nerves that may be the route by which the brain peptide, testis ecdysiotropin, reaches the testes. The cardiotesticular muscle and products sequestered in the cardiotesticular sinus may be involved in the fusion of the paired testes and maturation of the male reproductive system, because they are present only during this stage of development.