An unusual course of the thoracic duct in relation to the vertebral vessels

A variation in the course of the thoracic duct was found in the cervical portion of a male cadaver during routine dissection of the head and neck region for undergraduate students. The thoracic duct, while arching laterally above the clavicle, was coursing posterior to the vertebral vein but anterior to the vertebral artery; it normally passes anterior to both the vertebral vein and artery. To the best of our knowledge, this variation in relation to the vertebral vein has not yet been reported. In addition, after coursing posterior to the vertebral vein, the thoracic duct divided into two branches that drained separately, one at the angle between the internal jugular vein and subclavian vein, and the other into the subclavian vein. Knowledge of these variations is essential in order to prevent injury to the thoracic duct while performing surgeries at the root of the neck.

Morphology and imaging of bony projections on sigmoid sulcus with clinical implication

Morphologically diverse osseous projections were observed on the anterior lip of the sigmoid sulcus in a study conducted on 318 dry unsexed adult human skulls belonging to the Indian race. For convenience of description, this lip was divided into a longer lateral part, a shorter medial part and a junctional angular part having bony attributes characterized into three types, crests (42.9%), plates (22.3%) and bridges (13.5%). The bridges were subtyped into incomplete (11.8%) and complete (1.7%). Crests and plates were present anywhere along this lip, while bridges were confined to the angle. Right and left differences were analyzed, which showed that the above findings were more frequent on the right than the left. Plates showed a higher incidence of variation between right and left sides as compared to crests and bridges. Five cadavers were studied, which showed retinacular bands attached to the projections blending with dura mater over the foramen magnum. It is postulated that these projections are caused by the traction of the fibrous dural bands. Axial CT scan revealed partial and complete osseous bridges spanning the sulcus. These projections are of relevance to surgeons working at the cerebellopontine angle. Their presence has not been reported previously.

Distribution of serotonin-like immunoreactive nerves in major cerebral arteries of rabbit: an immunohistochemical study

We studied the distribution pattern of serotonin-like immunoreactive nerve fibers in the major cerebral vessels of rabbit by an indirect immunofluorescence technique using whole-mount stretch preparations. The density of serotonin-like immunoreactive nerve fibers was greater in vessels of the posterior part of the circle of Willis compared with that in the anterior part. This is in contrast to most of the observations reported previously regarding adrenergic, cholinergic, and peptidergic innervation of the circle of Willis.

Effect of oestrogen and progesterone on noradrenergic nerves and on nerves showing serotonin-like immunoreactivity in the basilar artery of the rabbit

The effects of oestrogen and progesterone on noradrenergic nerves and nerves with serotonin (5-HT)-like immunoreactivity in the basilar artery were investigated in the rabbit using whole-mount stretch preparations. The noradrenergic nerves were demonstrated by glyoxylic acid fluorescence histochemistry and nerves with 5-HT-like immunoreactivity by indirect immunofluorescence techniques. Quantitative image analysis of fluorescent nerve fibres revealed that nerve density and varicosity diameter of nerves with 5-HT-like immunoreactivity were significantly (P less than 0.01 and P less than 0.05 respectively) reduced after 4-week administration of oestrogen and the intensity of fluorescence was also reduced. However, there were no significant changes after progesterone. Neither oestrogen nor progesterone had any effect on noradrenergic innervation. The findings are discussed in relation to higher incidence of migraine headaches in females taking oral contraceptives.

Perivascular noradrenergic and peptide-containing nerves show different patterns of changes during development and ageing in the guinea-pig

The development of noradrenergic and peptide-containing perivascular nerves in common carotid, mesenteric, renal and femoral arteries of the guinea-pig was studied using the glyoxylic acid fluorescence and indirect immunofluorescence techniques on whole-mount stretch preparations at 6 stages between 6 weeks in utero and two years after birth. The noradrenergic plexus was more dense than the peptide-containing nerve plexuses in all the blood vessels, and, in general, calcitonin gene-related peptide-containing nerves were more numerous than substance P-containing nerves which in turn were more numerous than vasoactive intestinal polypeptide-containing nerves. In mesenteric and carotid arteries, noradrenergic nerve density reached a peak at about 4 weeks after birth that was maintained to old age, whereas the peptide-containing vasoactive intestinal polypeptide (VIP) and calcitonin gene-related peptide (CGRP) nerve plexuses reached a peak at birth and declined thereafter to about half maximum density in old age. In contrast, in the renal and femoral arteries, peptide-containing nerves reached a maximum density at 4 weeks after birth, while noradrenergic nerve density reached a peak around birth; both noradrenergic and peptide-containing nerve plexuses declined in density in old age. Of the 4 vessels studied, the mesenteric artery showed the greatest density of innervation for both noradrenergic and peptide-containing nerves at all stages of development, while the femoral artery was the least innervated. The possibility that some perivascular peptide-containing nerves play a trophic role during development is discussed.