Felipe Luis Schneider

Anatomic variations of anterior cerebral artery cortical branches

The anterior cerebral artery (ACA) is a major vessel responsible for the blood supply to the interhemispheric region. The ACA segment after the anterior communicating artery (AComA) origin is called the distal ACA and has central and cortical branches. The cortical branches are distributed in the different regions of the orbital and medial part of the brain. The objects of this study are the anatomical variations found in the distal ACA. In 76 hemispheres the ACA distal branches were injected with latex and dissected under microscope magnification. Vessel diameters and distances between vessel origins and anterior communicating artery were recorded and analyzed. Microsurgical dissection was carried out to demonstrate anatomic variations of these vessels. Average diameter of ACA at origin was 2.61 ± 0.34 mm and average diameter of cortical branches diameter ranged from 0.79 ± 0.27 mm to 1.84 ± 0.3 mm. Distances between vessel origin and AComA ranged from 7.68 ± 3.91 mm (orbitofrontal) to 112.6 ± 11.63 mm (inferior internal parietal). This study found anatomical variations: a single (azygos) ACA was present in one case and three in three cases. Crossing branches of the distal ACA to the contralateral hemisphere were present in 26% of the cases. In some cases a single ACA may supply the posterior hemispheric region through crossing branches. This calls attention to potential bilateral brain infarcts due to a single unilateral ACA occlusion. Clin. Anat. 13:231–236, 2000.

Topographical Distribution of Acetylcholinesterase in the Subfornical Organ of the Rat

Acetylcholinesterase (AChE) activity in the rat subfornical organ (SFO) was determined by the Koelle and Friedenwald method. Coronal sections showed a homogeneous reaction in the rostral region, which adopted a ring-like form in the anteromedial zone and a horseshoe pattern in the posteromedial zone. In the latter, AChE-specific positive neurons had been observed clearly in our sections. In sagittal sections the enzymatic reaction was intense in the anterior subependymal zone and dorsal region, and it continued caudally to the hippocampal area. The enzymatic activity was absent in the central region of the anteromedial zone and the subependymal region of the posteromedial zone. In sagittal sections the reaction was strongly positive in the periphery of the organ and negative in the posteromedial zone, near the choroid plexuses. Thus, we have shown that each region of the SFO presents a particular distribution of the AChE activity, related in some cases to neurons and in others to nerve fibers.

Regionalization of oviducts in Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) and its potential significance for fertilization

The structural analysis of oviducts in Boophilus microplus (Canestrini, 1887) in different stages of ingurgitation has indicated that they are constituted primarily of an internal cylinder and an external cylinder with different cell types being found between them. Copulated females in active ingurgitation process show typical variations along the internal cylinder, and three regions can be defined: anterior, ring-like and transitional. Based on such regionalization, hypotheses were raised about where and how fertilization takes place, a process yet to be clarified for the acari.

Anatomia microcirúgica da substâcia perfurada anterior basal humana

The anterior perforated substance (APS) is a landmark in the basal forebrain. It has a basal face located above the carotid bifurcation in the subarachnoid space, and an interhemispheric one. It is the site of passage of the arteries to the caudate nucleus, putamen, internal capsule, adjacent areas of the globus pallidus and thalamus. Fifty hemispheres from twenty-five adult cadavers were obtained. The arteries were perfused with colored latex, Batsons resin and gelatin colored with carmine. Using a surgical microscope we have determined the origin, local and number of origin from the parent vessel. The sites of penetration in the mediolateral and anteroposterior direction were also recorded. The anterior communicating artery contribution to the basal APS was reviewed. Significant vascular variations and anastomoses were encountered mainly involving middle cerebral and anterior choroidal arteries. The precise understanding of these vessels has surgical and clinical implications in the management of vascular and tumoral maladies related to the anterior perforated substance.

Postmortem Persistence of Acetylcholinesterase Activity in the Subfornical Organ of the Rat

Acetylcholinesterase (AChE) activity in the rat subfornical organ at 8, 12, 18, 24, 26, 28 and 30 h postmortem was evaluated by the Koelle and Friedenwald method. AChE activity was unchanged in animals 12 h postmortem. When the postmortem period was extended, enzymatic activity diminished, disappearing almost completely after 30 h.