title: A comparative study of annual changes in the pineal gland morphology with reference to the influence of melatonin on testicular activity in tropical birds, Psittacula cyanocephala and Ploceus philippinus.
abstract: The aim of the present comparative investigation was to examine annual pineal cytological changes and the action of melatonin in relation to testicular activity in two wild tropical avian species. The findings revealed that in both blossomheaded parakeets (Psittacula cyanocephala) and Indian weaver birds (Ploceus philippinus) the pineal gland was inactive, with reduced karyometric values during the breeding season. A pinealoactive phase showing significantly increased pinealocyte nuclear diameter corresponded with the nonbreeding phase. Administration of melatonin (250 micrograms/100 g body wt) for 10 consecutive days caused significant involution of testes during the breeding phase, although it failed to alter reproductive activity during the nonbreeding phase. The results indicated that the pineal gland activity varied inversely with the seasonal testicular weight cycle and the antigonadal influence of melatonin appeared to be phase dependent, which corroborated the inverse temporal relationship of the pineal gland and male reproductive activity examined in the two tropical avian species.
authors.affiliation: Department of Zoology, University of Calcutta, India.
authors.forename: S
authors.initials: S
authors.lastname: Chakraborty
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001717:Birds / Q000502:physiology*; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D010870:Pineal Gland / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D011563:Psittaciformes / Q000502:physiology*; D012098:Reproduction; D012621:Seasons; D013045:Species Specificity; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D008550:Melatonin