Frink R, Krupp P P, Young R A
J Morphol. 1978 Oct;158(1):91-107. doi: 10.1002/jmor.1051580108.
The ultrastructure of the pinealocyte in the woodchuck, Marmota monax, was studied during the four seasons of the year. Fall cells have a fairly uniform cytoplasmic density, organelles consistent with synthetic and/or secretory activity and rather extensive pericapillary and intercellular spaces. Many winter pinealocytes are nearly devoid of ribosomes and granular endoplasmic reticulum but contain lipid droplets associated with mitochondria. Pericapillary and intercellular spaces are minimal. Spring glands have the greatest variation in cytoplasmic density with intercellular and pericapillary spaces similar to that seen in fall glands. Cells containing electron dense cytoplasm have Golgi zone associated, secretory granules, free ribosomes, short sections of granular endoplasmic reticulum and dense bodies. Cells with a more electron lucent cytoplasm are similar to the most frequently observed summer pinealocytes which have numerous Golgi zones but few associated secretory granules. Microtubules are prominent in the cytoplasm of these cells, the plasma membranes are smooth and intercellular and pericapillary spaces are minimal. A yearly rhythm or cyclic activity of the pinealocyte is suggested.
对美洲旱獭（Marmota monax）松果体细胞的超微结构进行了全年四个季节的研究。秋季细胞的细胞质密度相当均匀，细胞器与合成和/或分泌活动一致，毛细血管周围和细胞间空间相当广泛。许多冬季松果体细胞几乎没有核糖体和粗面内质网，但含有与线粒体相关的脂滴。毛细血管周围和细胞间空间最小。春季腺体的细胞质密度变化最大，细胞间和毛细血管周围空间与秋季腺体相似。含有电子致密细胞质的细胞有高尔基区、分泌颗粒、游离核糖体、粗面内质网短节段和致密体。细胞质电子密度较低的细胞与夏季最常见的松果体细胞相似，后者有许多高尔基区，但相关分泌颗粒较少。微管在这些细胞的细胞质中很突出，质膜光滑，细胞间和毛细血管周围空间最小。提示松果体细胞存在年度节律或周期性活动。
