Organização supramolecular de fibrilas colágenas estromais em córneas de falconiformes e strigiformes

• Ano de defesa: 2020
• Autor(a) principal: Pereira, Amanda Garcia
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade de Franca; Brasil; Pós-Graduação; Programa de Mestrado em Ciência Animal; UNIFRAN
• Palavras-chave em Português: Ave de rapina; Birrefringência; Luz polarizada; Matriz extracelular; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA
• Link de acesso: https://repositorio.cruzeirodosul.edu.br/handle/123456789/1176

Falconiformes and Strigiformes are raptors that perform activities during the day and night, respectively. Their eyes differ in their ability to resolve details of objects in the monocular and binocular visual fields. Such differences have been associated with many factors, including variations in the configuration of the components of the optical system. The cornea is the element of the optical system that is in direct contact with the external environment and its refractive functions arise from the supramolecular organization of the type I fibrillar collagen that makes up the stroma. The hypothesis of this study is that there are supraorganizational differences between stromal collagen fibrils in the corneas of Falconiformes and Strigiformes. To test the hypothesis, 22 corneas excised from Falconiformes of the species Caracara plancus, Rupornis magnirostris, and Falco sparverius and 28 from Strigiformes of the species Tyto furcata, Pseudoscops clamator, and Athene cunicularia were processed histotechnically for sections of 8 μm in thickness. Optical retardation values associated with total, form, and intrinsic birefringences were measured using a polarized light microscope equipped with phase compensators. Coherence coefficients (orientation) of collagen fibrils were calculated by video image analysis. All assessments were conducted both in the anterior and posterior stroma of the cornea. The data were analyzed using uni- and multivariate statistical methods. Differences were significant when p < 0.05. The results confirmed the study's hypothesis. Differences between Falconiformes and Strigiformes were found in the anterior stroma. The optical retardations associated with total and form birefringences were higher for Falconiformes (p < 0.0001). In contrast, the coherence coefficients were higher for Strigiformes (p = 0.0168). Multivariate statistics showed that the final dissimilarity between Falconiform and Strigiform corneas, in terms of supraorganization of stromal collagen fibrils, was 4.56%. It is possible that the supraorganizational differences reported in this study are sources of variation of the visual quality of Falconiformes and Strigiformes. Thus, the results of this pioneering research provide the necessary evidence to motivate new studies relating the power resolution and the refractive performance of the optical system with the supramolecular characteristics of the corneal stromal collagen. Key words: bird of prey; birefringence; extracellular matrix; eye; polarized light.