'A' is the basilar part of the pons. Note the notch on its ventral side : in three dimensions this would be seen as the sulcus for the basilar artery.

The basilar part contains all that the pyramid of the medulla oblongata does, and much more. You can see the descending pyramidal fibres broken up into bundles (on both sides of the letter 'A'). The grey masses are the pontine nuclei. Fibres from from all over the cerebral cortex terminate on the neurones of the pontine nuclei. Fibres from the pontine nuclei are seen here as transverse bundles in the basilar part. These fibres cross over and reach the opposite cerebellum through the middle cerebellar peduncles. Revivew the cerebellar inputs at this stage.

'B' is a middle cerebellar peduncle. It is a massive bundle. (In a section at a appropriate level one can see fibres of the trigeminal nerve passing through this mass to emerge on the ventral surface.)

The remaining part of this section is the tegmentum.

The three tracts which were close to the midline in the medulla oblongata are parting company gradually. The pyramidal fibres are all in the basilar part. The medial lemniscus has been twisted now, in the area around 'C', the medial longitudinal fasciculus keeping closer to the the floor of the ventricle. The spinal lemniscus is pushed and spread out laterally beyond the medial lemniscus. There is also a new arrival here, the lateral lemniscus which is a part of the auditory pathway. Do not attempt to identify these precisely, these sweep out in an arc beginning with the medial lemniscus.

The elevation at 'E' is due to the nucleus of VI with the fibres of VII curving around it. In this picture we do not see the fibres of the VII. Few bundles of VI are seen coursing ventrally at 'D'. Ventrolateral to the nucleus of VI would be the facial nerve (VII) nucleus, and further laterally the principal sensory nucleus of V. (The motor nucleus of V would be a bit rostral).