Functional Histology: The Tissues of Common Coleoid Cephalopods

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.

Ocular anatomy and correlation with histopathologic findings in two common octopuses (Octopusvulgaris) and one giant Pacific octopus (Enteroctopusdofleini) diagnosed with inflammatory phakitis and retinitis

“…The stages of cataracts and posterior segment changes could not be determined due to a severely miotic pupil that was nonresponsive to topical tropicamide 1% ophthalmic solution (Alcon Pharmaceutical, Genève, Switzerland) and atropine 1% ophthalmic solution (Bausch & Lomb, Rochester, NY, USA). This lack of response to parasympatholytic agents is consistent with previous studies that have been unable to identify an iris sphincter or dilator muscles in this species 6–12 …”

“…This lack of response to parasympatholytic agents is consistent with previous studies that have been unable to identify an iris sphincter or dilator muscles in this species. [6][7][8][9][10][11][12] Both animals were euthanized 6 months following their ophthalmic examination as they displayed advanced signs of senescence including lack of feeding, retraction of skin around the eyes, uncoordinated movement, and increased undirected activity. 19 For euthanasia, the same anesthetic procedure was used as described above, but the animals were kept in the bucket with the anesthetic for >45 minutes, or until they had stopped breathing for approximately 15 minutes.…”

“…This class also includes squid and cuttlefish. 6,7 The ocular anatomy of octopuses is similar in many ways to that of vertebrates and is an example of convergent evolution. 8 Literature regarding diseases in octopus species is becoming increasingly available, but information regarding ocular disease is still lacking.…”

“…Octopuses are invertebrate species in the class Cephalopoda. This class also includes squid and cuttlefish 6,7 . The ocular anatomy of octopuses is similar in many ways to that of vertebrates and is an example of convergent evolution 8 .…”

Can Cephalopods Vomit? Hypothesis Based on a Review of Circumstantial Evidence and Preliminary Experimental Observations

“…Still, Boucaud-Camou and Boucher-Rodoni (1983 , p. 164) comment that “ sphincters enable both the caecum and the stomach to be isolated from the rest of the digestive tract .” This statement was not referenced, but we have concluded that it refers to observations from S. officinalis published in Boucaud-Camou (1977) and/or from drawings in the anatomical monograph of S. officinalis by Tompsett (1939 , Figure 46) showing sphincters at the esophagus-stomach, stomach-caecum, and stomach-intestine junctions. A recent guide to the functional anatomy of cephalopods does not describe sphincters between any of these structures in the section on the digestive tract ( Guerra, 2019 ), and this is also the case for a chapter including a survey of the histology of the digestive tract ( Anadon, 2019 ), and a research paper describing the anatomical and histochemical features of the O. vulgaris digestive tract ( Fernandez-Gago et al, 2019 ). More detailed histological and functional studies are required to resolve the issue of the presence of sphincters between key regions of the cephalopod digestive tract.…”