Three-Dimensional Analysis of the Nasolacrimal Duct and Nasal Cavity and Arrangement of Mucosal Tissue in Chickens

Abstract

The nasal mucosa plays an important role in the immune system, with nasal mucous cells secreting mucin that, along with pili, exclude foreign substances from intervening. Nasal mucosal-associated lymphoid tissue (NALT), present in the nasal lamina propria, acts as a local immune system. In birds, the Harderian gland in the orbit also plays an important role in the local immune system. In this study, we analyzed the pathway from the nasolacrimal duct to the nasal cavity in chickens and the distribution of the nasal mucous cells responsible for defense mechanisms against pathogens. To determine the threedimensional structure of the pathway from the nasolacrimal duct to the nasal cavity, we made casts of the anatomy by injecting an acrylic resin into the area. We then prepared paraffin sections to determine the distribution of the NALT and mucous cells. The mucous gland was clearly seen in the mucosal epithelium of the nasal cavity, suggesting that the pathway along the nasal cavity develops a nonspecific immune system to deal with large foreign substances, such as bacteria, using mucins that are secreted from the mucous glands. Hence, there is not only a physical barrier but also an antibacterial activity. Unlike in other animals, morphologically, the nasolacrimal duct in chicken becomes the ventral nasal meatus and opens into the choanae in the caudal portion of the nasal cavity. NALT was prominently present in the lamina propria of the ventral nasal meatus, suggesting the presence of a specific immune system protecting against avian viruses. Thus, responses to vaccine stimulation could be developed from tissues along the pathway of the ventral nasal meatus via the nasolacrimal duct running from the punctum. These morphological studies suggest that the instillation of eye drops could be used as an efficient vaccination method for avoiding respiratory diseases.

Ocular mucosal homeostasis of teleost fish provides insight into the coevolution between microbiome and mucosal immunity

“…When vertebrates first colonized terrestrial environments, their ocular surface underwent further evolutionary adaptations, including the development of novel adnexa such as the lacrimal gland, movable eyelids, and eyelashes in the case of mammals. These structures provide protection for the eye, keeping the Cor clean and moist, and enabling adaptation to dry land environments [9][10][11][12]. It is important to note that throughout the evolutionary timeline of vertebrates, the ocular surface underwent significant adaptive changes required for survival under various environmental pressures, particularly during the water-to-land transition [13].…”

Histopathological findings of the nasopharynx-associated lymphoid tissue of pigs co-infected with porcine circovirus 2 and porcine reproductive and respiratory syndrome virus

“…NALT plays an important role in the defense mechanism of the body against the early stages of infectious diseases and is considered critical to the development of mucosal vaccines. However, a few pathological studies on the nasopharynx, including the NALT, have been performed in domestic animals [ 14 , 43 ]. The present study aimed to histopathologically examine the lymphoid tissue, including the NALT, of pigs with suspected PCV2 and PRRSV infection.…”