Fenestration of the vertebrobasilar junction.

A fenestration of the vertebrobasilar junction was found in an 80-year-old man during autopsy. It was associated with thrombosis of the vertebral arteries which had caused a left Wallenberg syndrome. The left limb of the fenestration presenting the same transverse diameter as that of the remaining part of the basilar artery appeared to be its direct (true) origin. The right limb had a lesser transverse diameter and appeared to bridge the lateral surface of the rostral end of the right vertebral artery and the basilar trunk. According to the authors, this fenestration could have been caused by the persistence of the cranial part of a primitive lateral vertebrobasilar anastomosis, rather then by the usual incomplete fusion of the primitive paired basilar arteries

Pivotal role of the sub-supracardinal anastomosis in the development and course of the left renal vein

A retroaortic left renal vein is encountered frequently in the dissecting room and in radiological investigations. A number of recent reports of this variation led us to review the development of the renal veins and the inferior vena cava to understand its etiology. For further insight, we also examined our collection of serial sections of cat embryos. In human embryos of about 15 mm the "renal collar," a venous ring around the aorta, is formed by anastomoses between subcardinal and supracardinal veins. The ventral part of the "renal collar" is formed from the intersubcardinal anastomosis, the dorsal part from the intersupracardinal anastomosis and the lateral parts from the sub-supracardinal anastomoses. The primitive renal veins drain venous blood from the metanephros into the sub-supracardinal anastomoses. A retroaortic left renal vein would form if the dorsal part of the sub-supracardinal anastomosis and the intersupracardinal anastomosis persist whereas the ventral part of the sub-supracardinal anastomosis and the intersubcardinal anastomosis regress

The persistent primitive hypoglossal artery: a rare anatomic variation with frequent clinical implications.

The case of a persistent primitive hypoglossal artery (PHA) in a 72-year-old man dead from myocardial infarction is presented. The autopsy showed the presence of a semicircular marginal infarct on the surface of the left cerebral hemisphere. The PHA anastomized the basilar artery origin with the left internal carotid artery, running through the left hypoglossal canal together with the hypoglossal nerve. The vertebral and posterior communicating arteries were hypoplastic. The PHA represented the morphological base on which the cerebral vascular insufficiency acted, following the generalized circulatory insufficiency due to the myocardial infarct, causing the cerebral infarct. Based on the embryology of the cranial arteries and on the morphological findings we suggest that the persistence of the hypoglossal artery: 1) precedes the vertebral and posterior communicating arteries hypoplasia causing it by competition for the territory of distribution; 2) gives rise to an almost complete dependence of the cerebral circulation from the carotid system with predictable ischemic consequences in the case of a critical reduction of the carotid blood flow; 3) may be associated with an anomalous structure of the vessel wall and exposes the basilar trunk to an unusual haemodynamic stress, predisposing to the onset of aneurysms

Megalodolichobasilaris: the effect of atherosclerosis on a previously weakened arterial wall?

The morphological findings of 2 basilar artery giant fusiform aneurysms are presented. In one case (a 63-year-old man) the aneurysm was accidentally found at autopsy. Its wall was mainly formed by fibrous tissue without a smooth muscle layer and presented fragmented but still recognizable elastic lamina. In the media there were small well-formed bony spicules. In the other case (a 59-year-old man) the aneurysm had broken causing subarachnoid hemorrhage. The wall showed a marked reduction of smooth muscle cells and thinning and fragmentation of elastic lamina. A second sacciform aneurysm was present at the basilar tip. The review of the literature and the morphological findings of the 2 cases, characterized by abnormality of the portion of the basilar artery not directly involved in the aneurysm wall, consisting of a diffuse deficit of the tunica media and lamina elastica, might suggest that the fusiform aspect of the aneurysm may be the result of the degenerative effect of atherosclerosis on a cogenital, structural or dysmetabolic, or acquired, inflammatory, weakening of the arterial wall

Trophic factors in the carotid body.

The aim of the present study is to provide a review of the expression and action of trophic factors in the carotid body. In glomic type I cells, the following factors have been identified: brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, artemin, ciliary neurotrophic factor, insulin-like growth factors-I and -II, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-alpha and -beta1, interleukin-1beta and -6, tumour necrosis factor-alpha, vascular endothelial growth factor, and endothelin-1 (ET-1). Growth factor receptors in the above cells include p75LNGFR, TrkA, TrkB, RET, GDNF family receptors alpha1-3, gp130, IL-6Ralpha, EGFR, FGFR1, IL1-RI, TNF-RI, VEGFR-1 and -2, ETA and ETB receptors, and PDGFR-alpha. Differential local expression of growth factors and corresponding receptors plays a role in pre- and postnatal development of the carotid body. Their local actions contribute toward producing the morphologic and molecular changes associated with chronic hypoxia and/or hypertension, such as cellular hyperplasia, extracellular matrix expansion, changes in channel densities, and neurotransmitter patterns. Neurotrophic factor production is also considered to play a key role in the therapeutic effects of intracerebral carotid body grafts in Parkinson's disease. Future research should also focus on trophic actions on carotid body type I cells by peptide neuromodulators, which are known to be present in the carotid body and to show trophic effects on other cell populations, that is, angiotensin II, adrenomedullin, bombesin, calcitonin, calcitonin gene-related peptide, cholecystokinin, erythropoietin, galanin, opioids, pituitary adenylate cyclase-activating polypeptide, atrial natriuretic peptide, somatostatin, tachykinins, neuropeptide Y, neurotensin, and vasoactive intestinal peptide

Hieronymous Fabricius ab Acquapendente (1533-1619)

Born Hieronymus Fabricius in 1533 at Acquapendente, he began studying Greek, Latin, and philosophy at the University of Padova as a teenager. By his twentieth birthday he was studying medicine and had become the favored pupil of Fallopius, whom he succeeded in 1565 as professor of anatomy and surgery. Fabricius was a renowned and popular teacher who did everything he could to avoid teaching (Favaro, 1922a). Though more inclined toward research than lecturing, Fabricius\u2019 dedication to academia is unquestionable. In 1594 he built the first permanent theatre ever designed for public anatomical dissections, thus revolutionizing the teaching of anatomy (Fig. 2). Since the 15th century Paduan anatomists had carried out anatomical dissections only during the cold months in a temporary theatre set up in a ventilated place and built as the arena of Verona or the Colosseum in Rome, with the cadaver placed in the center. The Rector of the University, who was a student, had to locate every year two cadavers of criminals under penalty. The students were allowed to assist with the dissections only if they had studied for 2 years and had paid a fee.,..

The course of the posterior inferior cerebellar artery may be related to its level of origin

The course of the posterior inferior cerebellar artery (PICA) was analyzed with reference to its origin and relationships with the medullary and cerebellar surfaces and the adjacent cranial nerves in 40 brains after the injection with acrylic resins of the vertebrobasilar system. In 42.5% of instances, the PICA originated from the lateral medullary segment of the vertebral artery (VA), in 32.5% from its premedullary segment, in 22.5% from the basilar artery (BA), and in 2.5% it was absent. With reference to the level of origin, three patterns of course for the lateral medullary segment of the PICA can be outlined. (1) When it arises from the lateral medullary segment of the VA, it passes below the hypoglossal nerve, and the lateral medullary segment may form a loop with an anterosuperior convexity towards the pontomedullary sulcus (41%), or it may follow a rectilinear course (41%). It passes at the level of the accessory nerve. The tonsillomedullary (TM) segment shows a caudal loop and the telovelotonsillary (TVT) has a cranial loop. (2) When the PICA arises from the BA, it passes above the hypoglossal nerve. The lateral medullary segment forms a loop with lateral convexity (78%) and passes above or through the glossopharyngeal nerve, frequently showing a recurrent course among the roots of the IX, X, or XI cranial nerve. The TM and the TVT segments do not have loops. (3) When the PICA arises from the premedullary segment of the VA, it passes above, below, or through the rootlets of the hypoglossal nerve. In the lateral medullary segment, it follows a rectilinear course (54%) and passes the plane formed by the IX, X, and XI cranial nerves at an intermediate level with respect to the other two patterns. The TM and the TVT segments show caudal and cranial loops. The different origins and courses of the PICA derive from the selection of different branches of the primitive vertebrobasilar plexus during the development of the cerebellum. The existence of an embryologic correlation between the course of the PICA and its level of origin may be useful in the evaluation of its angiographic anatomy