The Development of the Sulci and Gyri of the Bovine Cerebral Hemispheres

<jats:title>Summary</jats:title><jats:p>This study contributes to the existing knowledge and includes a complete description of the gyri and sulci of the bovine cerebral hemisphere, the chronological order of appearance of these sulci and gyri and the ages at which the sulci and gyri reach their final pattern as seen in the bovine adult.</jats:p><jats:p>The research was undertaken because this specific area has not been covered by anatomists in any depth. The results of this study will contribute to the more complete descriptions of the anatomy of the bovine adult, as well as of the embryological development of the animal.</jats:p><jats:p>A number of bovine embryos and fetuses were collected from the abattoir. Serial sections of the embryos were studied histologically, while the brains of the fetuses were examined macroscopically or with a dissection‐microscope.</jats:p><jats:p>Up until day 58 the cerebral hemisphere is smooth. Then an indentation appears which marks the position of the <jats:italic>Fissura sylvia.</jats:italic> The <jats:italic>Sulcus rhinalis lateralis</jats:italic> appears at day 68. At day 90 the following grooves are visible: the <jats:italic>Sulcus suprasylvius</jats:italic>, the <jats:italic>Sulcus cinguli</jats:italic>, the <jats:italic>Sulcus splenialis</jats:italic>, the <jats:italic>Sulcus genualis</jats:italic>, and the <jats:italic>Sulcus corporis callosi.</jats:italic> At this age, all the gyri associated with these sulci develop, although the gyri are well developed only after the grooves have formed. At day 110 the <jats:italic>Sulcus ectosylvius</jats:italic>, the <jats:italic>Sulcus marginalis</jats:italic>, and the <jats:italic>Sulcus presylvius</jats:italic> are visible, once again with their associated gyri appearing a short time thereafter. At day 130 the following grooves are visible: the <jats:italic>Sulcus coronalis</jats:italic>, the <jats:italic>Sulcus cruciatus</jats:italic>, the <jats:italic>Sulcus ansatus</jats:italic>, and the <jats:italic>Sulcus endomarginalis.</jats:italic> The cerebrum of the foetus at this stage has well developed gyri. At day 160 the <jats:italic>Sulcus proreus</jats:italic>, the <jats:italic>Sulcus ectomarginalis</jats:italic>, the <jats:italic>Sulcus suprasplenialis</jats:italic>, the <jats:italic>Sulcus endosplenialis</jats:italic>, the <jats:italic>Sulcus calcarinus</jats:italic>, and the <jats:italic>Sulcus endogenualis</jats:italic> have developed. The final groove to form is the <jats:italic>Sulcus rhinalis medialis.</jats:italic> Then the brain looks like that of the adult animal.</jats:p>