Anatomical Studies on the Cell Column Located Closely Medial to the Nucleus of the Spinal Root of the Trigeminal Nerve in the Sperm and the Pygmy Sperm Whales

A specific cell column was examined anatomically, which was located closely medial to the nucleus of the spinal root of the trigeminal nerve of the medulla oblongata in two sperm whales and a pygmy sperm whale. This cell column was observed extending at the level from the obex to the uppermost medulla in the sperm whale and at the level of the middle one third of the medulla oblongata in the pygmy sperm whale. After the precise comparative anatomical and histological investigations, the author has come to the conclusion that the cell column is thought to be the structure corresponding to the lateral cervical nucleus which has highly developed in the level of the medulla oblongata.