Ultrastructure of the Juxtaganglionar Organ,a Putative Endocrine Gland Associated with the Cerebral Ganglia of Aplysia juliana

Summary

Electron microscopy was used to examine the morphology of a putative endocrine gland, the juxtaganglionar organ (JO), and its relation to the cerebral ganglia of the hermaphroditic opisthobranch gastropod Aplysia juliana. The JO is a well-vascularized, poorly innervated tissue of glandular cells—rich in mitochondria, lipids, ribosomes, and endoplasmic reticulum, with sparse cilia and membrane-limited secretory granules—within the connective tissue sheath just exterior to the neuronal soma in the dorsal and posterior portions of the cerebral ganglia. The cytology and organization of the JO supports its homology to the dorsal bodies of pulmonate gastropods, which axe endocrine organs known to release one or more female gonadotropic factors.