In the peccary the cortical envelope sends radial projections inward, the spaces between being occupied by medullary substance; and this, on a large scale, is the structure of the porcupine's quills.
As a result this fluid in the medullary and deep cortical regions of the kidney becomes highly concentrated, reaching concentrations of up to four times that of the plasma (1,200 mosmoles per litre), mainly owing to the accumulation of sodium and chloride.
In some families medullary thyroid carcinomas are the only tumours that appear, whereas in other families medullary thyroid carcinomas are one component of multiple endocrine neoplasia type 2 (MEN2).
However, despite marked increases in serum calcitonin concentrations, patients with medullary thyroid carcinoma do not have low serum calcium concentrations (hypocalcemia), because their tissues are resistant to calcitonin.
Nearly all patients affected by medullary thyroid carcinoma or MEN2 have hereditary mutations in the RET (rearranged during transfection) proto-oncogene (a gene that can become a cancer-causing gene, or oncogene).
The corticospinal tract is not merely a pathway to medullary and spinal motor neurons.
At medullary levels the two spinothalamic tracts merge and cannot be distinguished as separate entities.
Injuries or disease of the lateral medulla may cause lateral medullary syndrome, which is associated with a loss of pain and temperature sensations, loss of the gag reflex, difficulty in swallowing, vertigo, vomiting, or loss of coordination.
During the part of the life cycle prior to egg formation, a marked increase in osteoblastic activity occurs along the inside surfaces of the long bones, and the medullary cavities become filled with spongy bone.
The diaphysis and metaphysis are nourished primarily by the nutrient artery, which passes through the cortex into the medullary cavity and then ramifies outward through haversian and Volkmann canals to supply the cortex.
Injuries or diseases affecting the middle portion of the medulla may result in medial medullary syndrome, which is characterized by partial paralysis of the opposite side of the body, loss of the senses of touch and position, or partial paralysis of the tongue.
