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.

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.

Acetylcholinesterase distribution in the central nervous system of the Megalobulimus oblongus (Gastropoda, Pulmonata).

The acetylcholinesterase (AChE) in the central nervous system (CNS) of the Megalobulimus oblongus was demonstrated by using Koelle and Friedenwald's procedure. The AChE positive reaction was revealed in the nervous cell bodies and processes in the different ganglia of the CNS. The largest number of strong positive neuronal subsets reside in pedal and buccal ganglia. Other positive cell bodies are also located in clusters in the left portion of the visceral ganglion, meso and postcerebrum, and pleural ganglia. In some neurons the enzymatic reaction only appeared at trophospongium level. The neuropilian synaptic areas also exhibited AChE reactivity. These data provide further evidence that AChE is present in neuronal bodies of the CNS of this pulmonate snail, and in some areas is probably involved in cholinergic circuits.