Histological and three dimensional organizations of lymphoid tubules in normal lymphoid organ of Penaeus monodon
Introduction
The lymphoid or Oka organ was first described in Penaeus orientalis by Oka [1], and later in Sicyonia ingentis by Martin et al. [2] who incorrectly described it as haematopoietic nodules. The lymphoid organ of penaeid shrimp consists of two lobes situated ventro-anterior to the hepatopancreas [3]. Each lobe receives the haemolymph from the anterior aorta via the subgastric artery [3], [4], which is further branched several times in each lobe of the lymphoid organ. At the light microscope level, the lymphoid organ is composed of two parts: lymphoid tubules and the spaces in between which are occupied by haemal sinuses. Lymphoid tubules consist of the central lumen lined by flattened endothelial cells. Next to the endothelial lining are two types of stromal cells. Cells in the inner layer have a clear, unstained cytoplasm, whereas those in the outer layer have a more darkly stained cytoplasm with H and E staining [4]. It is believed that haemocytes penetrate the endothelial cells into the space between stromal cells, where they settle and later migrate into the haemal sinuses which form part of the open circulatory system [3]. Apart from cellular constituents, there is a connective tissue scaffold that provides support for the lymphoid tubules. In penaeid shrimp, there is no detailed description of the fibrous scaffold of the lymphoid organ. Furthermore, the three dimensional structure of lymphoid tubules and their relationship with the branching subgastric artery have never been demonstrated. In this study the normal lymphoid organ of Penaeus monodon, which tested negative for white spot syndrome virus (WSSV) and yellow head virus (YHV), was studied by light microscopy using special staining and transmission electron microscopy in order to demonstrate the histological organization, cellular components, and the connective tissue scaffold, and by a vascular cast technique and SEM to visualize the three dimensional structure of the tubules.
Section snippets
Shrimps
Wild caught fully mature P. monodon were obtained from the Gulf of Thailand. The shrimps were confirmed to be WSSV-negative by PCR and YHV-negative by RT-PCR using the IQ 2000 detection kit (Farming IntelliGene Technology Corporation, Taipei, Taiwan).
Tissue preparation for light microscopic observation
Dissected lymphoid organs were fixed in Davidson's fixative, dehydrated through ascending concentrations of ethanol, cleared with dioxane, and embedded in paraffin wax. Four to six micron thick sections were cut and stained with hematoxylin–eosin
Gross anatomy of lymphoid organ
The lymphoid organs were paired and lay ventral to the stomach and dorso-anterior to the ventral hepatopancreas (Fig. 1A). Each lymphoid organ had an ovoid shape and was connected to the heart via the subgastric artery. In the fully mature shrimp (with the body length of 18–20 cm from head to telson, and body weight of 150–170 g), lymphoid organs were about 3–4 mm long, 2–3 mm wide, and 1–2 mm thick.
General histology of lymphoid organ
Each lymphoid organ was surrounded by a connective tissue capsule (Fig. 1B). The capsule invaginated
Discussion
The structural organizations of lymphoid organs of penaeid shrimp have been studied by many authors, i.e., in P. orientalis by Oka [1], in S. ingentis by Martin et al. [2], and in Penaeus stylirostris by Bell and Lightner [4]. These authors described the lymphoid organ as being made up of lymphoid tubules which are the basic unit. It is believed that this organ plays a very important role against infection especially by viruses, as it is essentially a filtering organ that clears the haemolymph
Acknowledgements
This research was supported by the Commission on Higher Education (PhD. Scholarship to P. Duangsuwan and Research Group Grant to P. Sobhon) and TRF (Senior Research Scholar Fellowship to P. Sobhon).
References (18)
- et al.
The roles of haemocytes and the lymphoid organ in the clearance of injected Vibrio bacteria in Penaeus monodon shrimp
Fish Shellfish Immunol
(2002) - et al.
Isolation, culture, and characterisation of MHC class II-positive microvascular endothelial cells from the human heart
Microvasc Res
(1996) - et al.
The role of the antennal glands in ion and body volume regulation of cannulated Penaeus monodon reared in various salinity conditions
Comp Biochem Physiol A
(2000) A review of fixed phagocytic and pinocytotic cells of decapod crustaceans, with remarks on hemocytes
Dev Comp Immunol
(1987)Studies on Penaeus orientalis Kishinouye-VIII structure of the newly found lymphoid organ
Bull Jpn Soc Sci Fish
(1969)- et al.
Structure of hematopoietic nodules in the ridgeback prawn, Sicyonia ingentis: light and electron microscopic observations
J Morphol
(1987) - et al.
A handbook of normal penaeid shrimp histology
(1996) - et al.
Scanning electron microscopic study on pineal vascularization of the common tree shrew (Tupaia glis)
J Pineal Res
(1991) - et al.
Cytokeratin 7 and 20 staining for the diagnosis of lung and colorectal adenocarcinoma
Br J Cancer
(2002)
Cited by (9)
Ultrastructure of cells constituting lymphoid tubules and circulating hemocytes in Penaeus monodon
2022, Fish and Shellfish ImmunologyVirulence of Vibrio harveyi responsible for the " Bright-red" Syndrome in the Pacific white shrimp Litopenaeus vannamei
2012, Journal of Invertebrate PathologyCitation Excerpt :Egusa et al. (1988) reported similar pathological changes in the LO of Penaeus japonicus experimentally infected with Vibrio sp. where no extensive necrotic lesions were found in other organs. It is believed that the LO is essentially a filtering organ that clears the hemolymph of infectious agents as well as for homeostatic improvement of the hemolymph filtrate (Van de Braak et al., 2002; Duangsuwan et al., 2008). In the present study, severe necrosis was also observed within muscle fibers at the site of injection and surrounding connective tissue as well as antennal gland and gill filaments.
Insight into the lymphoid organ of penaeid prawns: A review
2010, Fish and Shellfish ImmunologyCitation Excerpt :In the ridgeback prawn, Sicyonia ingentis with an average body weight of 14.5 g, the LO had an oval shape and ranged between 1 × 1.5 mm to 1.5 × 4 mm in size [18]. The lymphoid organ of the black tiger prawn, Penaeus monodon with a body weight of 150–170 g (body length of 18–20 cm) was ovoid in shape and measured around 3–4 mm in length, 2–3 mm in width, and 1–2 mm in thickness [14]. In addition, viral infection may cause enlargement of the lymphoid organ.
Differential gene expression in black tiger shrimp, Penaeus monodon, following administration of oxytetracycline and oxolinic acid
2009, Developmental and Comparative ImmunologyChanges in the histological organization and spheroid formation in lymphoid organ of Penaeus monodon infected with yellow head virus
2008, Fish and Shellfish ImmunologyCitation Excerpt :At TEM level, it became clear that most cells in this type of spheroid were highly vacuolated and contained apoptotic nuclei (Fig. 5H). In general, both fibrous components exhibited similar patterns to those of normal lymphoid tubule where PAS-intensely stained extracellular matrix (ECM) were associated with type 1 fibers, and Gomori's stained type 2 (reticular) fibers (see ref. [23] for complete description). However, the staining of ECM and associated type 1 fibers within spheroids appeared much less intense, and less organized than in normal tubules (Fig. 6A,B).
A Novel TRIM9 Protein Promotes NF-κB Activation Through Interacting With LvIMD in Shrimp During WSSV Infection
2022, Frontiers in Immunology