Neurosecretory Pathways in the Prawn, Leander serratus

Abstract

LAST year, I reported the presence of neurosecretory cells within the tritocerebral commissure of Penæus braziliensis, and the distribution of fuchsinophil droplets along the course of two post-commissure nerves¹. Two flat extensions of these nerves, adjoining blood sinuses and therefore described as sinus-plates, were full of these droplets. Injection experiments showed that those regions with the most droplets yielded the most potent extracts when these were tested by their effects on the white chromatophores. The sinus-plates resemble the sinus-glands of the Mysidacea², and this parallel has been made more striking by the recent evidence of Enami³, Passano⁴ and others that the sinus-glands of some decapods are supplied by neurosecretory cells in the medulla terminalis; the secretory products pass along nerves and are released via secretory canals in the sinus-glands². In the present experiments a search was made for secretory canals in the tritocerebral commissure and the post-commissure nerves of the prawn, Leander serratus. The nervous system was stained by a modification of the methylene blue method used by Alexandrowicz⁵; specimens were immersed in a solution of methylene blue for nine hours in a refrigerator.