title: Asymmetric post-natal development of superior cervical ganglion of paca (Agouti paca).
abstract: Functional asymmetry has been reported in sympathetic ganglia. Although there are few studies reporting on body side-related morphoquantitative changes in sympathetic ganglion neurons, none of them have used design-based stereological methods to address this issue during post-natal development. We therefore aimed at detecting possible asymmetry-related effects on the quantitative structure of the superior cervical ganglion (SCG) from pacas during ageing, using very precise design-based stereological methods. Forty (twenty left and twenty right) SCG from twenty male pacas were studied at four different ages, i.e. newborn, young, adult and aged animals. By using design-based stereological methods the total volume of ganglion and the total number of mononucleate and binucleate neurons were estimated. Furthermore, the mean perikaryal volume of mononucleate and binucleate neurons was estimated, using the vertical nucleator. The main findings of this study were: (1) the right SCG from aged pacas has more mononucleate and binucleate neurons than the left SCG in all other combinations of body side and animal age, showing the effect of the interaction between asymmetry (right side) and animal age, and (2) right SCG neurons (mono and binucleate) are bigger than the left SCG neurons (mono and binucleate), irrespective of the animal age. This shows, therefore, the exclusive effect of asymmetry (right side). At the time of writing there is still no conclusive explanation for some SCG quantitative changes exclusively assigned to asymmetry (right side) and those assigned to the interaction between asymmetry (right side) and senescence in pacas. We therefore suggest that forthcoming studies should focus on the functional consequences of SCG structural asymmetry during post-natal development. Another interesting investigation would be to examine the interaction between ganglia and their innervation targets using anterograde and retrograde neurotracers. Would differences in the size of target organs explain ganglia structural asymmetry?
authors.affiliation: Laboratory of Stochastic Stereology and Chemical Anatomy (LSSCA), Department of Surgery, College of Veterinary Medicine, University of São Paulo (USP), São Paulo, Brazil.
authors.forename: Luciana Maria Bigaram
authors.initials: LM
authors.lastname: Abrahão
authors.forename: Jens Randel
authors.initials: JR
authors.lastname: Nyengaard
authors.forename: Tais Harumi de Castro
authors.initials: TH
authors.lastname: Sasahara
authors.forename: Sílvio Pires
authors.initials: SP
authors.lastname: Gomes
authors.forename: Felipe da Roza
authors.initials: Fda R
authors.lastname: Oliveira
authors.forename: Fernando Vagner Lobo
authors.initials: FV
authors.lastname: Ladd
authors.forename: Aliny Antunes Barbosa Lobo
authors.initials: AA
authors.lastname: Ladd
authors.forename: Mariana Pereira de
authors.initials: MP
authors.lastname: Melo
authors.forename: Márcia Rita Fernandes
authors.initials: MR
authors.lastname: Machado
authors.forename: Samanta Rios
authors.initials: SR
authors.lastname: Melo
authors.forename: Antonio Augusto Coppi Maciel
authors.initials: AA
authors.lastname: Ribeiro
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000818:Animals; D017776:Autonomic Pathways / Q000166:cytology / Q000254:growth & development; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D049108:Cell Enlargement; D002467:Cell Nucleus / Q000502:physiology / Q000648:ultrastructure; D007839:Functional Laterality / Q000502:physiology; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000502:physiology; D012377:Rodentia / Q000033:anatomy & histology / Q000254:growth & development; D017783:Superior Cervical Ganglion / Q000166:cytology* / Q000254:growth & development*; D017779:Sympathetic Fibers, Postganglionic / Q000166:cytology / Q000254:growth & development