Macroscopic and microscopic study of trachea in Caspian seal (Pusa caspica)

Subject Areas : Journal of Comparative Pathobiology

M Moghani Ghahramanloo ¹ , MT Sheibani ² , A Taheri Mirghaed ³

1 - Phd student, Basic Sciences Department, Veterinary Faculty, University of Tehran, Tehran, Iran.
2 - Associate Professor, Basic Sciences Department, Veterinary Faculty, University of Tehran, Tehran, Iran
3 - Professor, Aquatic Health Department, Veterinary Faculty, University of Tehran, Tehran, Iran.

Received: 2023-04-25 Accepted : 2023-07-01 Published : 2023-08-23

Keywords: Caspian seal, Trachea, Microscopic, Macroscopic,

Abstract :

In this study, performing for the first time, the tracheas of 5 Caspian seals were examined. For macroscopic study, the appearance features of the tracheas and the position of their cartilaginous rings were carefully examined. For microscopic examination, after the usual histological procedures, 6-micron sections were prepared and stained with hematoxylin-eosin, periodic acid Schiff, Masson's trichrome, Verhoeff and Alcian blue and studied with a light microscope. The macroscopic results showed that the tracheal lumen was elongated in an oval shape, but in the anterior surface of the trachea the cross section was completely round. The cartilaginous rings are C-shaped, but the cartilages located caudal to the cricoid cartilage appear as complete rings. The number of cartilaginous rings in 5 samples was between 85 and 95 cartilages, and their complete rings are about 28. The histological results showed that the epithelium is pseudo stratified columnar with many goblet cells. The lamina propria consists of loose connective tissue containing dense lymphatic tissues and the submucosa is composed of dense connective tissue. The presence and density of the collagen and elastic fibers in the submucosa seem to be higher than in the lamina propria, and a wide vascular network with lacunal spaces and valve-like structures can be seen in the connective tissues of the trachea. The muscles of the trachea are mainly oriented in the longitudinal direction and the cartilaginous rings in the dorsal region of the trachea overlap in several layers.

References:

1. Sharipov R. Caspian seal (Phoca caspica Gmelin, 1788) and its current status in the Caspian Sea. Journal of Black Sea / Mediterranean Environment. 2012; 18(3): 350-359.


2. Harkonen T, Jüssi M, Baimukanov M, Bignert A, Dmitrieva L, Kasimbekov Y, Verevkin M, Wilson S, Goodman SJ. Pup production and breeding distribution of the Caspian seal (Phoca caspica) in relation to human impacts. AMBIO: A Journal of the Human Environment. 2008 Jul;37(5):356-61.


3. Kooyman GL. Deep diving. In “The Biology of Marine Mammals”,(Ed. HT Andersen), 65-94.


4. Falke KJ, Hill RD, Qvist J, Schneider RC, Guppy M, Liggins GC, Hochachka PW, Elliott RE, Zapol WM. Seal lungs collapse during free diving: evidence from arterial nitrogen tensions. Science. 1985 Aug 9;229(4713):556-8.


5. Reidenberg JS. Anatomical adaptations of aquatic mammals. The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology: Advances in Integrative Anatomy and Evolutionary Biology. 2007;290(6):507-13.


6. Denk M, Fahlman A, Dennison-Gibby S, Song Z, Moore M. Hyperbaric tracheobronchial compression in cetaceans and pinnipeds. Journal of Experimental Biology. 2020 Mar 1;223(5):jeb217885.


7. Reidenberg JS, Laitman JT. Anatomy of the hyoid apparatus in odontoceli (toothed whales): specializations of their skeleton and musculature compared with those of terrestrial mammals. The Anatomical Record. 1994 Dec;240(4):598-624.


8. Bancroft JD, Gamble M. Theory and practice of histological techniques. 6th ed. London: Churchill Livingstone; 2008. p. 303-20.


9. Kiernan J. Histological and histochemical methods. Scion Publishing Ltd; 2015 Jun 8.


10. Fanning JC. The structure of the trachea and lungs of the South Australian bottle-nosed dolphin. Functional anatomy of marine mammals. 1974;2:231-52.


11. Cozzi B, Bagnoli P, Acocella F, Costantino ML. Structure and biomechanical properties of the trachea of the striped dolphin Stenella coeruleoalba: evidence for evolutionary adaptations to diving. The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology: An Official Publication of the American Association of Anatomists. 2005 May;284(1):500-10.


12. Moore MJ, Hammar T, Arruda J, Cramer S, Dennison S, Montie E, Fahlman A. Hyperbaric computed tomographic measurement of lung compression in seals and dolphins. Journal of Experimental Biology. 2011 Jul 15;214(14):2390-7.


13. Ballarin C, Bagnoli P, Peruffo A, Cozzi B. Vascularization of the trachea in the bottlenose dolphin: comparison with bovine and evidence for evolutionary adaptations to diving. Royal Society Open Science. 2018 Apr 18;5(4):171645.


14. Kida MY. Morphology of the tracheobronchial tree of the Ganges river dolphin (Platanista gangetica). Okajimas folia anatomica Japonica. 1990 Oct 20;67(4):289-95.


15. Nakakuki S. The bronchial tree and lobular division of the lung in the striped dolphin (Stenella coeruleo-albus). Journal of Veterinary Medical Science. 1994 Dec 15;56(6):1209-11.


16. Tarasoff FJ, Kooyman GL. Observations on the anatomy of the respiratory system of the river otter, sea otter, and harp seal. II. The trachea and bronchial tree. Canadian Journal of Zoology. 1973 Feb 1;51(2):171-7.