Pacinian corpuscle in the human pancreas

Gross and histological morphology of the cervical gill slit gland of the pygmy sperm whale (Kogia breviceps)

Odontocete cetaceans have undergone profound modifications to their integument and sensory systems and are generally thought to lack specialized exocrine glands that in terrestrial mammals function to produce chemical signals (Thewissen & Nummela, 2008). Keenan-Bateman et al. (2016, 2018), though, introduced an enigmatic exocrine gland, associated with the false gill slit pigmentation pattern in Kogia breviceps. These authors provided a preliminary description of this cervical gill slit gland in their helminthological studies of the parasitic nematode, Crassicauda magna. This study offers the first detailed gross and histological description of this gland and reports upon key differences between immature and mature individuals. Investigation reveals it is a complex, compound tubuloalveolar gland with a well-defined duct that leads to a large, and expandable central chamber, which in turn leads to two caudally projecting diverticula. All regions of the gland contain branched tubular and alveolar secretory regions, although most are found in the caudal diverticula, where the secretory process is holocrine. The gland lies between slips of cutaneous muscle, and is innervated by lamellar corpuscles, resembling Pacinian's corpuscles, suggesting that its secretory product may be actively expressed into the environment. Mature K. breviceps display larger gland size, and increased functional activity in glandular tissues, as compared to immature individuals. These results demonstrate that the cervical gill slit gland of K. breviceps shares morphological features of the specialized, chemical signaling, exocrine glands of terrestrial members of the Cetartiodactyla.

Ectopic lamellar Pacinian corpuscle within the thymus. Atypical or abnormal location?

Lamellar (Pacinian) corpuscle is a cutaneous encapsulated sensory corpuscle, mainly functioning as a rapidly adapting low-threshold mechanoreceptor with characteristic "onion skin"-like appearance. Even though the Pacinian corpuscle is typically located in the skin, histomorphologically and confirmed by using immunohistochemical methods, we have identified it within the interstitium of the thymus of a newborn with congenital heart defect. To the best of our knowledge, this is the first such account ever to be published. The structure of the thymic Pacinian corpuscle was the same as the Pacinian corpuscle in the skin. The ectopic thymic Pacinian corpuscle can be hypothetically explained as the consequence of impaired migration of neural crest cells, since neural crest-derived cells play an important role in the development of the Pacinian corpuscle, as well as the thymus and heart. In general, the occurrence of ectopic Pacinian corpuscle in different organs is rare. In the scientific literature, there are reports of its sporadic presence in the pancreas, in the lymph nodes, inside the prostate and the urinary bladder wall. Our report presents the first described case of the Pacinian corpuscle in a heterotopic location in the thymus. Similar to other incidental findings of this anatomic structure, explanation of its ectopic development, as well as its local function remains only speculative.

Immunohistochemical profile of human pancreatic pacinian corpuscles

OBJECTIVES

To analyze the immunohistochemical profile of the human pancreatic pacinian corpuscles in comparison with that of the cutaneous pacinian corpuscles. In addition, we studied a Pacinilike corpuscle found in the adventitia of a pancreatic artery.

METHODS

We used immunohistochemistry to detect specific antigens for corpuscular constituents, specific antibodies for the identification of Adelta- and C-sensory fibers and for the detection of several growth factor receptors, and some members of the degenerin/epithelial Na channel superfamily of proteins.

RESULTS

Approximately 62% of pancreatic pacinian corpuscles have 2 to 10 axonic profiles each enclosed by its own inner core: 1 or 2 of these axonic profiles displayed RT-97 immunoreactivity (specific marker of mechanical axons). The cutaneous pacinian corpuscles showed not more than 2 axonic profiles with identical immunohistochemical characteristics. The expression of glial fibrillary acidic protein, epithelial membrane antigen, and tyrosine receptor kinase B was different between pancreatic and cutaneous pacinian corpuscles; the pattern of distribution of degenerin/epithelial Na channel proteins was identical in both cases. The arterial Pacinilike corpuscles displayed a specific immunohistochemical profile.

CONCLUSIONS

Pancreatic pacinian corpuscles slightly differ from the cutaneous ones, and these differences could be related to topography, growth factor requirements, or function of pacinian corpuscles in the pancreas.