Microfil distribution patterns in the head of sheep. Reference scales are provided either as a ruler in the image (mm) or as a labelled longitudinal bar. A – Sagittal view of sheep head showing yellow Microfil in the lymphatic vessels associated with the olfactory turbinates and distributed within the cavernous sinus. B – Higher magnification of a sagittal view of the cavernous sinus demonstrating yellow Microfil from the subarachnoid space and blue Microfil in the venous plexus. The green colour indicates some mixing of the two coloured Microfils. C – Coronal section illustrating yellow Microfil distributed around the pituitary gland and within the cavernous sinus. D – Histological section of the cavernous sinus (the dura is delineated by a dashed line) showing yellow Microfil (dark brown) located in the connective tissue adventitia (black arrow) of the internal carotid artery (ICA). In addition, residual Microfil can be observed in the tissues surrounding the pituitary gland and within the spaces around the venous plexus of the cavernous sinus (black arrows). Most of the Microfil at the latter location has been lost during tissue processing. However, the dilated spaces (DS) presumed to originally contain the contrast agent, are clearly seen. Some of the venous channels are labeled (V). E – Enlargement of Fig 1D demonstrating Microfil deposition in the adventitia (black arrows) surrounding the internal carotid artery (ICA). F – Histological section showing the venous structure of the cavernous sinus. The spaces between the veins are dilated and are presumed to have contained Microfil that was lost on tissue preparation. Some of the venous channels are labeled (V). G – Histological section of a portion of the trigeminal nerve. Microfil (black arrows) can be observed within the endoneurium of the nerve. H – Cut surface of the trigeminal nerve (dashed circle) adjacent to the cavernous sinus (CS) showing yellow Microfil distribution within the nerve. Lymphatic vessels (white arrows) containing yellow Microfil can be seen emerging from the epineurium of the nerve.