Objective. To investigate the morphological properties of pig cerebral bridging vein. Methods. The morphology and fibre arrangement of 15 cerebral bridging veins obtained from 7 Danish Yorkshire landrace pigs were observed. Results. There was a narrow region at the junction of the cerebral bridging veins and superior sagittal sinus termed “ outflow cuff segment". The diameter and length of outflow cuff segment were much smaller and the thickness was higher than those of the cerebral bridging veins (P< 0.01), and circumferential collagen fibres were most dense in the outflow cuff segment. The opening angle of the outflow cuff segment and the cerebral bridging veins were 115± 4° and 120± 4° (P >0.05). Conclusions. There were differences in fibre arrangement and morphological properties between the outflow cuff segment and the cerebral bridging vein, just like a resistance valve, the outflow cuff segment may play an important role in stabilizing cerebral venous outflow and regulating intracranial pressure.

Host cell residue DNA is one of the most common impurity which can affect the safety of biological products,therefore,domestic and international regulatory agencies have required the limit for host cell residue DNA in different biological products,either at the final product qualification or the appropriate intermediate control stage.The removal effect is verified by monitoring the residue DNA of products in different production stages,which is beneficial for assuring the scientificity and stability of the production process.In order to strengthen the understanding of control strategy about host cell residual DNA,the paper reviews progress in host cell residual DNA in biological products by authors'work experience and other's research,which provides reference for future work.