An acinus (saclike cavity) in a gland.
The socket of a macrotrichium (seta).
Any of the many tiny air sacs in the lungs in which the bronchioles terminate and where oxygen and carbon dioxide are rapidly exchanged with the pulmonary capillaries.
The bony socket in which the root of a tooth resides.
The crown containing the viscera of crinoids and similar echinoderms, entoprocts, and the polyps of some cnidarians.
A chamber in the mammalian kidney through which urine passes.
The outermost whorl of flower parts, comprising the sepals, which covers and protects the petals as they develop.
A flattened cap of neuropil in the brain of insects.
A funnel-shaped expansion of the vas deferens or oviduct of insects.