hilum

Etymology

From Latin hīlum (“a trifle; a spot on a seed”).

noun

1. (botany) The eye of a bean or other seed; 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. 1913, Journal of the Washington Academy of Sciences, volume III, Washington, D.C.: Washington Academy of Sciences, →ISSN, →OCLC, page 141
   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. 2005, David Feldman, Do Elephants Jump? (Imponderables Book), New York, N.Y.: HarperCollins Publishers, page 24
2. (botany) 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. 1916, William Mansfield, Histology of Medicinal Plants, New York, N.Y.: John Wiley & Sons, →OCLC, page 188
3. (anatomy) A depression or fissure through which ducts, nerves, or blood vessels enter and leave a gland or organ; a porta.
   [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. 1998, R[obert] M[atthew] H[ay] McMinn, R. T. Hutchings, B. M. Logan, “Abdomen”, in The Concise Handbook of Human Anatomy, London: Manson Publishing, pages 144–145
   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). 2010, Benoît Ghaye, “Imaging of Hila and Pulmonary Vessels”, in Emmanuel E. Coche, Benoît Ghaye, Johan De Mey, Philippe Duyck, editors, Comparative Interpretation of CT and Standard Radiography of the Chest, Heidelberg: Springer, →DOI, page 166
   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. 2010, W. Richard Webb, Charles B. Higgins, Thoracic Imaging: Pulmonary and Cardiovascular Radiology, 2nd edition, Philadelphia, Pa., London: Lippincott Williams & Wilkins, page 161