Hydrocephalus model rat shows disrupted retinal development
Bottom line
Retinal development appears to be another casualty of Ccdc85c loss in a rat model already used to study congenital hydrocephalus. In a newly published Veterinary Pathology study, researchers from Osaka Metropolitan University and collaborators report that Ccdc85c knockout rats developed multifocal retinal dysplasia, disrupted photoreceptor inner and outer segments, abnormal cilia and rootlets, and impaired Müller cell development. Using immunohistochemistry, immunoelectron microscopy, fundus imaging, optical coherence tomography, and histology, the team localized CCDC85C to the outer limiting membrane tight junction complex in normal rat retina and linked its absence to disorganized retinal layer formation. The paper was published online September 5, 2026. (lifescience.net)
Why it matters: For veterinary professionals, the study broadens the relevance of the Ccdc85c knockout rat beyond brain malformations and positions it as a potential comparative model for developmental retinal disease. That matters because the same model had already been characterized as showing non-obstructive hydrocephalus, subcortical heterotopia, intracranial hemorrhage, and later abnormalities in neurogenesis, gliogenesis, and ependymal development. The new retinal findings suggest CCDC85C may have a wider role in epithelial junction organization and tissue layering than previously appreciated, which could be useful for pathologists, ophthalmology researchers, and translational teams studying congenital retinal dysplasia or cilia-associated disease mechanisms. (lifescience.net)
What to watch: Next will be whether this model is used for functional vision studies, cilia-focused retinal biology, or comparative work linking hydrocephalus-associated genes to ocular developmental defects. (lifescience.net)
Key facts
- Study type
- Veterinary Pathology study
- Model
- Ccdc85c knockout rats
- Main finding
- Multifocal retinal dysplasia and disrupted retinal layering
- Other retinal defects
- Disrupted photoreceptor inner and outer segments, abnormal cilia and rootlets, and impaired Müller cell development
- Normal retina finding
- CCDC85C localized to the outer limiting membrane tight junction complex
- Methods
- Immunohistochemistry, immunoelectron microscopy, fundus imaging, OCT, and histology
- Comparison group
- Wild-type F344 rats
- Publication date
- Online September 5, 2026
A rat model best known for congenital hydrocephalus may now offer a new window into retinal development. In Veterinary Pathology, investigators report that Ccdc85c knockout rats show disrupted retinal layering and structural defects that point to a direct role for CCDC85C in forming and maintaining the outer limiting membrane during retinal maturation. The article appeared online on September 5, 2026. (lifescience.net)
That finding builds on several years of work around Ccdc85c-deficient rodents. Earlier studies established the knockout rat as a model of genetic hydrocephalus after showing that animals with an approximately 350-base-pair deletion lacked CCDC85C protein and developed non-obstructive hydrocephalus, subcortical heterotopia, and intracranial hemorrhage, with features resembling the hemorrhagic hydrocephalus mouse model. A later follow-up study tied Ccdc85c loss to disrupted neurogenesis, gliogenesis, and ependymogenesis in the lateral ventricle, reinforcing the gene’s importance in developmental tissue organization. (jstage.jst.go.jp)
In the new retina-focused work, the researchers examined wild-type F344 rats from embryonic day 19 through postnatal day 20 and compared them with knockout animals using immunohistochemistry, immunoelectron microscopy, fundus photography, OCT, and histology. In normal retina, CCDC85C co-localized with ZO-1 in the outer limiting membrane and persisted after embryonic day 19; ultrastructurally, it was found between the outer nuclear layer and photoreceptor inner segments, in the same region as tight junctions. In knockout rats, the team found multifocal retinal dysplasia, disarrangement of inner and outer segments, cilia, and rootlets, plus impaired Müller cell development. OCT showed parallel hyperintense striations in the inner nuclear layer and reduced reflectivity in the outer limiting membrane and rod-cone layer. (lifescience.net)
Those details matter because they connect CCDC85C to a specific retinal microanatomy problem rather than a nonspecific consequence of severe brain disease. The authors’ interpretation is that CCDC85C is part of the tight junction complex and is involved in retinal layer formation. That fits with the group’s prior work, which repeatedly points to abnormal development of organized cellular barriers and support structures in Ccdc85c-deficient rats, including ventricular lining abnormalities and aberrant expression of developmental markers as hydrocephalus progresses. (lifescience.net)
I didn’t find an external press release or broad industry reaction tied specifically to this paper. Still, the surrounding literature gives the result added weight: the same research group and model have produced a consistent series of pathology studies across the cerebrum, ventricular system, and now retina, all centered on disrupted developmental architecture after Ccdc85c loss. Based on that pattern, it’s reasonable to infer that the retina paper is less a one-off observation than an expansion of an established disease model. (lifescience.net)
Why it matters: For veterinary pathologists and ophthalmology researchers, this study adds a potentially useful spontaneous-mechanism-style model for investigating retinal dysplasia, Müller cell maturation defects, and cilia-associated retinal abnormalities in a species that can be advantageous for imaging and developmental studies. It may also sharpen differential thinking in comparative pathology by highlighting how genes first studied in hydrocephalus can have parallel ocular phenotypes. More broadly, the work underscores how outer limiting membrane integrity and tight junction biology may shape retinal architecture in ways that are relevant across species, even if the immediate findings are preclinical. (lifescience.net)
What to watch: The next questions are whether investigators add electroretinography or behavioral vision testing to connect structure with function, whether other groups replicate the retinal phenotype, and whether Ccdc85c enters the conversation as a candidate gene in comparative studies of congenital ocular malformations. (lifescience.net)