Abstract
The knowledge of the organization of normal tissues and the changes occurring during physiological or pathological processes is basic to interpret the relationship between structure and function. There are numerous microscopic studies focused on different cephalopod organs that are based on the use of high-resolution methods as the transmission electron microscopy. However, there is no comprehensive basic histological guide to the different tissues in common species of cephalopods. To fill this gap, we present a careful description of the normal histological organization of cephalopods. Through 35 plates including 225 photomicrographs and the accompanying text descriptions, this chapter covers the body systems of three common species of European coleoid cephalopods, the cuttlefish (Sepia officinalis), the squid (Loligo vulgaris) and the octopus (Octopus vulgaris). The histology of the three species is presented in parallel, emphasizing those significant between-species differences. Sections used for study and photomicrographs were mostly stained with hematoxylin–eosin (H&E), a standard light microscopy method widely accessible for most laboratories of histology and pathology. Some sections of octopus were stained the Masson’s trichrome or the periodic acid–Schiff (PAS) methods.
Highlights
The microscopic anatomy or histology is based on examination of stained thin sections of the different structures of the body
The knowledge of the organization of normal tissues and the changes occurring during physiological or pathological processes is fundamental to interpret the relationship between structure and function
Most textbooks of histology are dedicated to human or mammalian tissues, and the scant books existing on comparative histology generally do not mention cephalopod tissues at all
Summary
The microscopic anatomy or histology is based on examination of stained thin sections of the different structures of the body. The skin of the cephalopods consists of a transparent epidermis formed of columnar epithelial cells and interspersed mucous cells, and a dermal layer of varying thickness formed of connective tissue that includes a number of chromatophores, iridophores and reflecting cells. The dermis mostly consists of a connective tissue formed of fibroblasts and networks of collagen fibers included in varied amounts of ground substance that exhibit in many places conspicuous chromatophore organs and other types of pigment cells below. Collagen fibrils are abundant in the skin and muscles of cephalopods, where they form fiber bundles with various orientations These fibers are eosinophilic in H&E stains but are better distinguished from muscle fibers with the Masson’s trichrome stain, showing a similar affinity for colorants as vertebrate collagen fibers.
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