Gross, histologic, and micro-computed tomographic anatomy of the lacrimal system of snakes

• Published in: Veterinary ophthalmology Vol. 18; no. s1; pp. 15 - 22
• Main Authors: Souza, Nicole M., Maggs, David J., Park, Shin Ae, Puchalski, Sarah M., Reilly, Christopher M., Paul-Murphy, Joanne, Murphy, Christopher J.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.01.2015
• Subjects: Animals; Harderian gland; Lacrimal Apparatus - anatomy & histology; nasolacrimal duct; ophidia; Snakes - anatomy & histology; Species Specificity; spectacle; subspectacular space; vomeronasal organ; vomeronasal organ; spectacle; subspectacular space; Harderian gland; nasolacrimal duct; ophidia
• ISSN: 1463-5216; 1463-5224
• DOI: 10.1111/vop.12184

Objective To describe the lacrimal system of snakes using contrast micro‐computed tomography (micro‐CT) with 3‐dimensional reconstruction, fluorescein passage (‘Jones’) testing, histology, and gross dissection. Animals studied One royal python and 19 snake cadavers representing 10 species. Procedures Direct observation following injection of fluorescein into the subspectacular space, micro‐CT following injection of three contrast agents into the subspectacular space, gross dissection following injection of latex into the subspectacular space, and histopathology. Results Injection of fluorescein confirmed patency, but not course of the lacrimal duct. Barium enabled clear visualization of the lacrimal duct, whereas two iodinated contrast agents proved inadequate. Collectively, micro‐CT, anatomic dissections, and histology suggest tears are produced by a single, large, serous, retrobulbar gland, released into the subspectacular space via several ductules, and drained through a single punctum originating in the ventronasal subspectacular space, and the lacrimal duct, which takes one of three routes of variable tortuosity before opening into the oral cavity in close association with the opening of the duct of the vomeronasal organ. Conclusions The ophidian lacrimal duct has a generally tortuous course, and the details of its anatomy are species‐variable. The tortuous course of the duct likely predisposes snakes to duct occlusion and must be considered when planning medical and surgical interventions in snakes with pseudobuphthalmos and subspectacular abscessation.