Histochemical and surface ultrastructural characteristics of the nasal cavity of laughing dove

Evaluation of Non-Vector Transmission of Usutu Virus in Domestic Canaries (Serinus canaria)

Usutu virus (USUV) is a flavivirus transmitted to avian species through mosquito bites that causes mass mortalities in wild and captive bird populations. However, several cases of positive dead birds have been recorded during the winter, a vector-free period. To explain how USUV "overwinters", the main hypothesis is bird-to-bird transmission, as shown for the closely related West Nile virus. To address this question, we experimentally challenged canaries with intranasal inoculation of USUV, which led to systemic dissemination of the virus, provided the inoculated dose was sufficient (>102 TCID50). We also highlighted the oronasal excretion of infectious viral particles in infected birds. Next, we co-housed infected birds with naive sentinels, to determine whether onward transmission could be reproduced experimentally. We failed to detect such transmission but demonstrated horizontal transmission by transferring sputum from an infected to a naive canary. In addition, we evaluated the cellular tropism of respiratory mucosa to USUV in vitro using a canary tracheal explant and observed only limited evidence of viral replication. Further research is then needed to assess if and how comparable bird-to-bird transmission occurs in the wild.

Morphological and functional relationship between the orbital gland and olfaction in Upupa epops (hoopoe) and Bubulcus ibis (cattle egret)

This study used both anatomical and histological techniques to investigate the orbital gland's topographic relationship with the surrounding system, using the hoopoe and cattle egret as biological models. Hoopoe has a spindle-shaped lacrimal gland that is suspended on the lateral edge of the frontal bone, whereas cattle egret has a tiny lacrimal gland that is embedded posteriorly within the periorbital fascia. The hoopoe's lacrimal gland has a single duct that runs parallel to the nasolacrimal duct and opens into the posterior nostril hole. In the cattle egret, the tubule-alveolar secretory components comprise neutral and acid glycosaminoglycan. In addition, the Harderian gland is found in both these species, but their draining ducts differ; the Harderian gland of the hoopoe opens into the anterodorsal to the conjunctival fornix, whereas the Harderian gland of the egret opens anteriorly. In both hoopoe and egret, the secretions of Harderian gland include neutral and acid glycosaminoglycan. The Harderian gland is categorized as type II in hoopoe and type I in cattle egrets. The present results concluded that both orbital glands of two bird species studied play an essential role in eye health, where cleaning and lubrication of the cornea surface. Furthermore, the lacrimal gland's location and secretory features may strengthen the olfactory sensitivity of hoopoe, which relies heavily on scent to locate their food, whereas egret relies heavily on visual cues.

Anatomical, histochemical and surface ultrastructural characteristics of cavum nasi of the common quails (Coturnix coturnix. Erlangeri)

Ten normal, mature and common quails were used to study in detail the gross anatomy, histochemical and surface ultrastructural characteristics of the nasal cavity. The relationship between the structure and function of the nasal cavity also were assessed. The quail nasal cavity was divided into the vestibule, nasal cavity proper and fundus. The nasal cavity began rostrally by two slit-like external nares located laterally in the middle third of the upper beak. A previous authors stated that no rostral concha but the current study record that the rostral nasal concha was located opposite the nostrils and exhibited a C-shaped appearance in transverse section and was 5 mm long and 3 mm wide. The middle nasal concha was narrow and elongated. The caudal nasal concha was spherical, located caudodorsal to the rostral nasal concha and measured 2 mm in diameter. The infraorbital sinus was a roughly triangular cavity situated immediately rostral to the orbit. The histological and surface ultrastructural study of the nasal cavity of common quail did not studied previously. Histologically, the cavum nasi was composed of three regions: vestibule, respiratory and olfactory. The vestibule was lined with stratified squamous epithelium that was keratinized rostrally and non-keratinized caudally. The respiratory region was covered by pseudostratified columnar epithelium. Intra-epithelial mucous glands were present in the respiratory region and displayed a strong reaction with Alcian blue. The lining epithelium in the olfactory region was pseudostratified and contained olfactory, supporting and basal cells.

Structural adaption of the nasal conchae of Eurasian common moorhen (Gallinula chloropus chloropus, Linnaeus, 1758)-Histomorphological study

In the current study, the nasal conchae of the Eurasian common moorhen were grossly and histologically examined for 20 healthy adult birds. Rostral (RC), middle (MC), and caudal (CC) conchae in each side of the nasal cavity were observed. The anatomical cross sections revealed that, the RC was noncurved in its rostral and middle parts, and one half turn in its caudal part. The MC was one half turn in its rostral part, one turn in its middle part, and one and one half turns in its caudal part. The CC was like a pouch from the lateral wall of the nasal cavity. Histologically, the distribution of the mucous glands was different among the three conchae; In RC, the ducts of these glands were intraepithelial, while the acini were located in the propria-submucosa toward the convex surface of the concha and absent toward its concave surface. In MC, they were intraepithelial and opened directly on the surface epithelium of the convex and concave surfaces. In CC, they were intraepithelial in few number near the convex surface of the concha and with abundant number in the propria-submucosa and absent near the concave surface. The RC was richer in the vascularity than the other two conchae. The nasal conchae were functioning for conditioning of the inspired air and entrapping the antigens presented in it.

Gross morphological features of the air sacs of the hooded crow (Corvus cornix)

Air sacs are considered to be one of the controlling factors of bird behaviour and habits in addition to their roles in ventilation, regulating body temperature, swimming and flight. As a scavenger and an omnivorous flight bird, air sacs of the hooded crow were the focus of this study. Eight healthy, adult hooded crows were used to examine the morphological characteristics of the air sacs, which were examined grossly and with latex and cast preparations. In general, the morphological overview of the hooded crow air sacs is similar to other avian species. We observed nine air sacs; four paired sacs (cervical, cranial thoracic, caudal thoracic and abdominal air sacs) and one unpaired sac; the clavicular air sac. The cervical air sac communicated to the lung through the medioventral bronchus and had three diverticula; intermuscular, subscapular and subcutaneous. The clavicular air sac communicated with lung through the medioventral bronchus and had subscapular, axillary, humeral, subpectoral and sternal diverticula. The cranial and caudal thoracic air sacs were communicated with lung through the lateroventral bronchi and the both sacs did not have any diverticula. The abdominal air sacs were posterior to the caudal thoracic air sacs. The left abdominal sac was the largest air sac. The right and left abdominal sacs gave off branches to diverticula that pneumatized synsacrum. The abdominal air sacs gave off femoral diverticula behind the hip joint as well as perirenal diverticula.