[MARMAM] New Publication: The Odontocete Ear Canal-Associated Lymphoid Tissue (ECALT) and Lymph Nodes

Steffen De Vreese steffendevreese at gmail.com
Wed Aug 31 07:43:57 PDT 2022

Dear all,

My co-authors and I are pleased to announce and share our recent paper titled
*The Odontocete Ear Canal-Associated Lymphoid Tissue (ECALT) and Lymph
Nodes: Morphological and Pathological Description with
Immuno-Phenotypic Characterisation*

De Vreese, S.; Centelleghe, C.; Graïc, J.-M.; Corrazola, G.;
IJsseldijk, L.L.; André, M.; Mazzariol, S. The Odontocete Ear
Canal-Associated Lymphoid Tissue (ECALT) and Lymph Nodes:
Morphological and Pathological Description with Immuno-Phenotypic
Characterisation. *Animals* *2022*, *12*, 2235.

Simple Summary:
The marine mammal immune system is of vital importance for the health of
any marine mammal. With changes in the natural environment and with
increasing anthropogenic stressors such as pollution, the immune system is
challenged to unknown extents. Dolphins and other odontocete cetaceans have
been shown to be particularly sensitive to anthropogenic influence in many
aspects. In this regard, it is important to understand how these animals
cope with novel stressors and how the immune system works and responds. In
studying parallel issues related to underwater noise pollution, we looked
at the cetacean ear canal and analysed in detail the cells of the immune
system. Like the skin, it is likely to be exposed to the external
environment and requires a local defence system as a first barrier to
incoming threats. We studied the ear-canal associated immune system and
describe the cell population using a variety of microscopic techniques. We
describe healthy and activated tissue and cases with inflammation of the
external ear canal and compare the different physiological states. As such,
this study contributes to acquiring a general understanding of the
odontocete cetacean immune system.

A changing marine environment with emerging natural and anthropogenic
stressors challenges the marine mammal immune system. The skin and adnexa
form a first protective barrier in the immune response, although this is
still relatively understudied in cetaceans. The cellular and tissue
morphology of the nodular and diffuse lymphoid tissue are not fully charted
and the physiological responses are not yet completely understood. The
odontocete’s external ear canal has a complex relationship with the
external environment, with an artificial lumen rendering the inside of the
canal a relatively secluded environment. In this work, we studied the
odontocete ear canal-associated lymphoid tissue (ECALT) by histo- and
immunohistochemistry (HC, IHC) with anti-CD3, anti-CD20, anti-Iba-1,
anti-HLA-DR, and anti-vimentin antibodies. The ECALT cellular composition
consists mainly of B-lymphocytes with the occasional presence of
T-lymphocytes and the dispersed distribution of the macrophages. In cases
of activation, the cellular reaction showed a similar pattern with the
occasional presence of T-cells, plasma cells, and neutrophils. Nodular
lymphoid tissue was generally in line with the description in other
odontocetes, although with abundant erythrocytes throughout the entire
organ. This study contributes to the understanding of the cellular
composition of diffuse and nodular lymphoid tissue in several species of
odontocetes, and in association with inflammation of the external ear canal.

The paper can be accessed here: https://www.mdpi.com/2076-2615/12/17/2235

Best regards,

Steffen De Vreese
Steffen De Vreese, MVM, PhD
Dipartimento di Biomedicina Comparata e Alimentazione (BCA) -
Università degli Studi di Padova (It)
Laboratori d'Aplicacions Bioacústiques (LAB) - Universitat Politécnica
de Catalunya (Es)
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