hilum

noun

1. The eye of a bean or other seed, or the center of that eye; the mark or scar at the point of attachment of an ovule or seed to its base or support.

   “The hilum is very prominent in some species and nearly flat in others.”

   “On the tip of each corn kernel is a hilum, collectively known as the "black layer," where it is attached to the cob. While corn is growing, nutrients are being transferred from the rest of the cob to the kernels through the hilum.”

2. The nucleus of a starch grain.

   “In central hilum starch grains the grain is laid down around the hilum in the form of concentric layers.”

3. A depression or fissure through which ducts, nerves, or blood vessels enter and leave a gland or organ.

   “[The pancreas] is a hook-shaped gland, about 15 cm long, that lies transversely across the upper abdomen, with the head in the C-shaped curve of the duodenum[…], extending to the left as the body behind the stomach and ending as the tail lying against the hilum of the spleen.”

   “The shadows of the hila on chest X-ray are mainly formed by the pulmonary arteries (PAs) and some of their main branches and the upper pulmonary veins (PVs).”

   “In the large majority of normal patients, the hila appear equal in size on frontal radiographs; comparison of the two hila is helpful in patients with a unilateral abnormality.”