Ultrastructure of the pineal gland of the mink (Mustela vison).

The pineal gland of the mink (Mustela vison) was examined, using light and electron microscopy. Its cellular structure was compared with that of the pineal gland in other mammalian species, including that of a close taxonomic relative, the ferret. The pineal gland of the mink was composed to pinealocytes and neuroglial cells, as well as numerous neuron cell processes and nerve endings, which provide extensive neural input to the pineal gland. A high degree of vascularity, extent of neural innervation, pinealocyte organelles, and presence of extensive pinealocyte processes with secretory granules indicate an active secretory function. This secretory function is postulated to be associated with the onset of the yearly reproductive cycle in the mink.