Ontogeny of Intrinsic Innervation in the Human Thymus and Spleen

Valsamo K. Anagnostou ^1*, Ipatia Doussis-Anagnostopoulou ¹, Dina G. Tiniakos ¹, Despina Karandrea ¹, Emmanouil Agapitos ¹, Petros Karakitsos ¹ and Christos Kittas ¹

¹ Laboratories of Histology and Embryology (VKA,ID-A,DGT,DK,CK) and Pathology (EA), Medical School, National and Kapodistrian University of Athens, Athens, Greece, and Department of Cytopathology, University General Hospital of Athens "Attikon", Athens, Greece (PK)

^* To whom correspondence should be addressed. E-mail: aisantha{at}hotmail.com.

Submitted on December 17, 2006
Accepted on 20 March 2007

	Abstract

The ontogeny of the innervation of human lymphoid organs has not been studied in detail. Our aim was to assess the nature and distribution of parenchymal nerves in human fetal thymus and spleen. Our material consisted of tissues from 23 human fetuses (18-39 gestational weeks-gw). We used the peroxidase immunohistochemical technique with antibodies specific to neuron specific enolase-NSE, neurofilaments-NF, PGP9.5, S100 protein and tyrosine hydroxylase-TH and evaluated our results with image analysis. In human fetal thymus, NSE-, NF-, S100-, PGP9.5- and TH- positive nerves were identified associated with large blood vessels from 18 gw onwards, increasing in density during development. Their branches penetrated the septal areas at 20 gw, reaching the cortex and the corticomedullary junction between 20 and 23 gw. Few nerve fibers were seen in the medulla in close association with Hassall’s corpuscles. In human fetal spleen, NSE-, NF-, S100-, PGP9.5- and TH- positive nerve fibers were localised in the connective tissue surrounding the splenic artery at 18 gw. Perivascular NSE-, NF-, S100-, PGP9.5- and TH- positive nerve fibers were seen extending into the white pulp mainly in association with the central artery and its branches increasing in density during gestation. Scattered NSE-, NF-, S100-, PGP9.5- and TH- positive nerve fibers and endings were localised in the red pulp from 18 gw onwards. The predominant perivascular distribution of most parenchymal nerves implies that the thymic and splenic innervation may play an important functional role during intrauterine life.

Key Words: fetal, human, thymus, spleen, innervation, immunohistochemistry, image analysis

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Guidelines | Subscriptions | About | exPRESS - Current - Archive | Business Information | Contact

The Journal of Histochemistry & Cytochemistry is owned, published, and licensed by The Histochemical Society © 2007