Histological and histochemical investigation of the compound eye of the whiteleg shrimp (Litopenaeus vannamei)
- Published
- Accepted
- Subject Areas
- Aquaculture, Fisheries and Fish Science, Anatomy and Physiology, Ophthalmology, Pathology, Histology
- Keywords
- Litopenaeus vannamei, compound eye, histology, foamy-glandular cells, screening pigments, neural cluster
- Copyright
- © 2017 Chang et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Histological and histochemical investigation of the compound eye of the whiteleg shrimp (Litopenaeus vannamei) PeerJ Preprints 5:e3453v1 https://doi.org/10.7287/peerj.preprints.3453v1
Abstract
The compound eye is the primary visual system in crustaceans. Although the histological structure and histochemical characteristics of compound eyes of some insect and crab species are now well understood, no such studies have been undertaken in the whiteleg shrimp (Litopenaeus vannamei). In this study, eye samples from L. vannamei were fixed and paraffin sections were stained using several histochemical methods. The histological structure of each layer of the compound eye was examined and compared using different histochemical staining methods. It was found that the compound eye of L. vannamei consisted of cuticle, cornea, ommatidia, optic nerve layer, lamina ganglionaris, and medulla in an outside-in order. The cuticle of L. vannamei eyes was very thin, composed of a single epicuticle layer, as confirmed by Masson’s trichrome stain. The screening pigments produced by screening pigment cells were arranged at the junction of the ommatidia and optic nerve layer; these pigments stained differentially after different histochemical staining methods suggesting the screening pigment cells can be classified into different types. Notably, clusters of foamy glandular cells (FGCs) were observed in the optic nerve layer; these stained positively with periodic acid-Schiff and toluidine blue, and appeared blue after Masson’s trichrome stain. Immunohistochemical (IHC) staining was used to further define the origin and characteristics of FGCs. The IHC analysis showed that FGCs were positive for vimentin and synaptophysin (SYN), suggesting their neuroendocrine nature. In the medulla internalis and medulla terminalis, the neural clusters that surround the neurophil could be divided into three types by differences in morphology: the largest and the smallest cell clusters were neuron clusters and neurosecretory cells, respectively; the middle-sized cell clusters appeared SYN-positive and have not previously been described. Overall, this study is the first to provide a detailed description of the normal features of the compound eye of L. vannamei. The identification of different types of screening pigments in the ommatidia, the endocrine nature of FGcs in the optic nerve layer, and the novel neural clusters between the medulla internalis and medulla terminalis, will be important information for further study into the compound eye of L. vannamei.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
White shrimp and crayfish cuticle of somite
H&E stain and Masson trichrome stain of the white shrimp and crayfish somite cuticle.
Pictures of toluidine blue stain-1
Pictures of toluidine blue stain of the white shrimp compound eye.
Pictures of toluidine blue stain-2
Pictures of toluidine blue stain of the white shrimp compound eye.
Pictures of toluidine blue stain-3
Pictures of toluidine blue stain of the white shrimp compound eye.
Pictures of toluidine blue stain-4
Pictures of toluidine blue stain of the white shrimp compound eye.
Pictures of PAS stain of the white shrimp compound eye
Pictures of PAS stain of the white shrimp compound eye.
Pictures of Luxol fast-PAS stain of the white shrimp compound eye
Pictures of Luxol fast-PAS white shrimp compound eye.
Pictures of MT stain-1
Pictures of MT stain of the white shrimp compound eye.
Pictures of MT stain-2
Pictures of MT stain of the white shrimp compound eye.
Pictures of MT stain-3
Pictures of MT stain of the white shrimp compound eye.