Surgical approach to internal and external jugular venous agenesis: case report.

PURPOSE: During reconstructive planning for mandibular resection and reconstruction, it was noted that the left internal and external jugular veins were absent, with a considerable compensatory internal jugular vein present on the contralateral side. METHODS: An accidental finding in the CT angiogram of the head and neck was assessed. RESULTS: Osteocutaneous fibular free flap is a well-established reconstructive surgery for mandibular defects that can involve anastomosis of the internal jugular vein and its tributaries. A 60-years-old man with intraoral squamous cell carcinoma, initially treated with chemoradiation, developed osteoradionecrosis of his left mandible. The patient then underwent resection of this portion of the mandible with reconstruction by osteocutaneous fibular free flap with virtual surgical planning. During reconstructive planning for the resection and reconstruction, it was noted that the left internal and external jugular veins were absent, and a noteworthy compensatory internal jugular vein was present on the contralateral side. We report a rare case of this combination of anatomical variations within the jugular venous system. CONCLUSION: Unilateral agenesis of the internal jugular vein has been reported, but a combined variation with ipsilateral agenesis of the external jugular vein and compensatory enlargement of the contralateral internal jugular vein has, to our knowledge, not been reported on previously. The anatomical variation reported in our study will be useful during dissection, central venous catheter placement, styloidectomy, angioplasty/stenting, surgical excision, and reconstructive surgery.

A short period of dark-adaptation is sufficient to generate light-induced photoreceptor degeneration in pigmented zebrafish.

Light-induced retinal degeneration (LIRD) models are used to recapitulate the pathologies of retinal diseases that affect photoreceptors. Current LIRD models use a dark-adaptation period of 7-14 days followed by high-intensity light exposure. The purpose of this study was to determine whether photoreceptor damage and death would occur in pigmented zebrafish using a short period of dark-adaptation. Zebrafish were dark-adapted for 24 h and then exposed to constant high-intensity light for 48 h. Immunohistochemical analysis was performed on vertical retinal sections to assess damage and apoptosis. Photoreceptors exhibited structural damage, apoptosis, and cell loss after 24 and 48 h of light exposure as previously reported in studies using 7-14 day dark-adaption. Also, photoreceptors lost following light damage were regenerated after 28 days. These results suggest that a short period of dark-adaptation is sufficient for a LIRD model in pigmented zebrafish.

Adenosine receptor expression in the adult zebrafish retina.

Adenosine is an endogenous nucleoside in the central nervous system that acts on adenosine receptors. These are G protein-coupled receptors that have four known subtypes: A1, A2A, A2B, and A3 receptors. In the present study, we aimed to map the location of the adenosine receptor subtypes in adult wild-type zebrafish retina using in situ hybridization and immunohistochemistry. A1R, A2AR, and A2BR mRNA were detected in the ganglion cell layer (GCL), the inner nuclear layer (INL), the outer nuclear layer (ONL), and the outer segment (OS). A3R mRNA was detected in the GCL, ONL, and OS. A1R-immunoreactivity was expressed as puncta in the INL and in the outer plexiform layer (OPL). A1Rs were located within the cone pedicle and contiguous to horizontal cell tips in the OPL. A2AR-immunoreactivity was expressed as puncta in the GCL, inner plexiform layer (IPL), INL, and outer retina. A2AR puncta in the outer retina were situated around the ellipsoids and nuclei of cones, and weakly around the rod nuclei. A1Rs and A2ARs were clustered around ON cone bipolar cell terminals and present in the OFF lamina of the INL but were not expressed on mixed rod/cone response bipolar cell terminals. A2BR-immunoreactivity was mainly localized to the Müller cells, while A3Rs were found to be expressed in retinal ganglion cells of the GCL, INL, ONL, and OS. In summary, all four adenosine receptor subtypes were localized in the zebrafish retina and are in agreement with expression patterns shown in retinas from other species.