Telencephalon vascularity in sheep (Ovis aries)

The studies into the vascularity of the telencephalon in Polish Merino sheep of both sexes were made on 60 cerebral hemispheres. It was found that the middle cerebral artery is the most powerful vessel supplying blood to the telencephalon. The artery gets divided into ten permanent branches. Two olfactory arteries supply the area of the telencephalon located on the border between the old and the new cortex. The other eight branches get divided into three branches running to the region of the frontal lobus of the brain, two branches - to the region of the parietal lobus and three temporal branches heading for the temporal region, supplying blood to the new cortex only. The frontal, parietal and temporal branches descended independently from the main trunk of the middle cerebral artery or first formed a common trunk. Common trunks for respective groups of branches have been referred to as: the anterior, superior and posterior middle cerebral arteries. The posterior olfactory artery in 6.7% of the cases was an independent branch from the rostral cerebral artery.(AU)

Anomalies, aneurysm and histology of the middle cerebral artery in Nigerian Africans

The histology of the middle cerebral artery (MCA) in Nigerian Africans has not been previously studied. One hundred MCAs obtained at autopsy from fifty adult Nigerians were studied. The vessels were processed and stained with Ehrlich's haematoxylin and eosin, elastic Van Gieson and Masson's trichrome stains. Early branches were given off before the perforators in two middle cerebral arteries, and there was one accessory MCA, making an incidence of anomalies of 3 percent. No aneurysm was observed in any of the cases. The internal elastic laminas were well developed but the external elastic laminas of the vessels were poorly developed. Close to the bifurcations the tunica media tapered gradually and at the bifurcations, the tunica media was completely deficient being replaced by the tunica adventitia (Forbus raphé). The tunica adventitia was thicker at the bifurcations (0.21mm) compared to other sites of the vessel. The average thickness of the MCA tunica media at its origin was 0.12mm while that of the tunica adventitia was O.lOmm. These results are similar to what has been described in the literature for Caucasians. It buttresses the assertion that anatomical anomalies of the MCA are rare. The seemingly low frequency of MCA aneurysms in Nigerian Africans is not due to its anomalies or histology.

La histología de la arteria cerebral media (ACM) de los africanos de Nigeria no ha sido previamente estudiada. Fueron examinadas 100 ACM, obtenidas en autopsias de 50 individuos nigerianos adultos. Las arterias fueron procesadas y teñidas con hematoxilina y eosina de Ehrlich, Van Gieson para fibras elásticas y tricrómico de Masson. Ramas proximales se originan antes de la división en dos arterias cerebrales medias, y había una ACM accesoria, constituyendo una incidencia de anomalías del 3 por ciento. No se observó aneurisma en ninguno de los casos. La lámina elástica interna estaba bien desarrollada, pero la lámina elástica externa de los vasos estaba pobremente desarrollada. Cerca de la bifurcación la túnica media es gradualmente cónica, la túnica media es totalmente deficiente siendo sustituida por la túnica adventicia (Forbus raphé). La túnica adventicia es más gruesa en las bifurcaciones (0.21mm) en comparación con otros lugares del buque. El grosor medio de la túnica media de ACM en su origen fue 0.12mm mientras que el de la túnica adventicia de O.lOmm. Estos resultados son similares a los que han sido descritos en la literatura para Caucásicos. Es importante la afirmación que las anomalías anatómicas de la ACM son raras. La aparentemente baja frecuencia de los aneurismas de ACM en nigerianos africanos no es debido a sus anomalías o a la histología.