Ortiz Leal, I. | bioRxiv Science

bioRxiv2024

Characterization of Eye and Adnexal Tissues in Dogs and Wolves: A Histological and Lectin-Histochemical Approach

This study explores the ocular anatomy and glandular components of domestic dogs compared to their ancestor, the wolf, with the aim of identifying evolutionary changes due to domestication and their implications for ocular pathologies. Utilizing histological and histochemical techniques, including hematoxylin-eosin, PAS, Alcian Blue, and lectins, this research conducts a detailed analysis of the canine and wolf ocular systems, particularly focusing on the eyelids, tarsal glands, and conjunctival tissues. Results indicate significant histological differences between the two species, particularly in the thickness and secretion levels of the conjunctival epithelia and the structure of the tarsal glands. Dogs exhibit a thicker epithelium with greater PAS and Alcian Blue positive secretion, suggesting enhanced ocular protection and lubrication adapted to domestic environments. Conversely, wolves display more concentrated glandular secretions and a predominance of acidic mucopolysaccharides, aligning with their adaptation to natural habitats. This study also highlights the translational value of dogs as models for human ocular diseases, given their anatomical and physiological similarities with humans. Such comparisons are essential as they provide insights that can lead to advancements in medical research and clinical applications, especially in the development of treatments for ocular surface disorders.

neuroscience↗

bioRxiv2024

The Incisive Duct as a Pathway for Early Vomeronasal Communication in Neonatal Dogs

The detection of chemical signals by the vomeronasal organ (VNO) is critical for communication among mammals from an early age, influencing behaviors such as suckling and recognition of the mother and conspecifics. Located in a concealed position at the base of the nasal cavity, the VNO features a duct covered with a sensory epithelium rich in neuroreceptors. A critical aspect of VNO functionality is the efficient access of stimuli from the nasal and oral cavities to the receptors. In adult dogs, it has been demonstrated through in vivo magnetic resonance imaging and anatomically postmortem how the VNO duct (VD) communicates to the environment through the incisive duct (ID). However, in newborn puppies, the existence of functional communication between the ID and the VD has not been confirmed to date, raising doubts about the potential physiological obliteration of the ID due to its small size and the degree of immaturity of the puppies at birth. Determining this aspect is necessary to evaluate the role played by chemical communication in this critical phase for the survival and socialization of puppies. This study employs serial histological staining techniques to examine the presence and functionality of the incisive duct in neonatal dogs. The serial histological sections have confirmed both the existence of functional communication between both the vomeronasal and incisive ducts in perinatal puppies, and the dual functional communication of the incisive duct with the oral and nasal cavities. The ID shows an uninterrupted lumen along its path and is associated with a sophisticated cartilaginous complex that prevents its collapse, as well as erectile tissue rich in blood vessels and connective tissue that acts as a cushion, facilitating its action under pressure induced by sampling behaviors such as tonguing. This investigation demonstrates the communicative capabilities of the VNO during the perinatal stage in dogs.

neuroscience↗