Cataldo A M, Broadwell R D
J Histochem Cytochem. 1984 Dec;32(12):1285-94. doi: 10.1177/32.12.6094657.
The endoplasmic reticulum (ER) and glycogen in secretory cells of anterior pituitary glands from control and fasted mice were investigated ultrastructurally using cytochemical staining techniques. Potential enzyme cytochemical markers for the ER included glucose-6-phosphatase (G6Pase) and nucleoside diphosphatase (NDPase) activities. Presumptive glycogen particles were identified in tissue postfixed in 1% osmium tetroxide-1.5% potassium ferrocyanide or in ultrathin sections poststained with periodic acid-thiocarbohydrazide-silver proteinate. The ER appeared to be related structurally and cytochemically to the nuclear envelope and cis Golgi saccules. Similar relationships between the ER and the trans Golgi saccules or GERL were not observed. In anterior pituitary glands from control mice, G6Pase activity was prominent within the lumen of the ER, nuclear envelope, and cis Golgi saccules of all cells; reaction product was absent in the trans Golgi saccules and in GERL. G6Pase activity was sparse to non-existent in anterior pituitary cells from fasted mice. The cytochemical reaction utilizing the Gomori lead capture method indicated that G6Pase in anterior pituitary cells may function as a phosphohydrolase for converting glucose-6-phosphate to glucose. Cytochemical localization of NDPase activity was not evident in the ER; reaction product was localized consistently in one or two trans Golgi saccules and occasionally in GERL and nascent secretory granules. Presumptive glycogen particles in each of the different secretory cell types from control mice appeared as 20-30 nm wide, electron-dense particles scattered as single entities throughout the cytoplasm. Anterior pituitary glands from fasted mice exhibited conspicuous and numerous clumps of glycogen particles in addition to scattered particles in all cell types except corticotrophs, which appeared to be devoid of glycogen. Glycogen particles were absent in anterior pituitary cells incubated in a medium containing diastase. Our results suggest that in anterior pituitary cells of the mouse: 1) the phosphohydrolytic activity of G6Pase is a reliable cytochemical marker for the ER; 2) the ER is associated morphologically and cytochemically with the cis face but not with the trans face of the Golgi apparatus or with GERL; 3) some glucose-6-phosphate, a possible substrate for G6Pase in vivo, may be derived indirectly from glycogen stores; and 4) modulations in G6Pase activity and glycogen storage during fasting may reflect an alteration in energy metabolism.
采用细胞化学染色技术，对正常小鼠和禁食小鼠垂体前叶分泌细胞中的内质网（ER）和糖原进行了超微结构研究。内质网潜在的酶细胞化学标记物包括葡萄糖 - 6 - 磷酸酶（G6Pase）和核苷二磷酸酶（NDPase）活性。在经1%四氧化锇 - 1.5%亚铁氰化钾后固定的组织中，或在经高碘酸 - 硫代碳酰肼 - 蛋白银染色的超薄切片中，可识别出推测的糖原颗粒。内质网在结构和细胞化学上似乎与核膜及顺面高尔基体囊泡相关。未观察到内质网与反面高尔基体囊泡或GERL之间有类似关系。在正常小鼠的垂体前叶中，所有细胞的内质网腔、核膜和顺面高尔基体囊泡内G6Pase活性显著；反面高尔基体囊泡和GERL中无反应产物。禁食小鼠垂体前叶细胞中G6Pase活性稀少或不存在。利用Gomori铅捕获法的细胞化学反应表明，垂体前叶细胞中的G6Pase可能作为磷酸水解酶将葡萄糖 - 6 - 磷酸转化为葡萄糖。内质网中NDPase活性的细胞化学定位不明显；反应产物始终定位于一两个反面高尔基体囊泡，偶尔定位于GERL和新生分泌颗粒中。正常小鼠不同分泌细胞类型中的推测糖原颗粒表现为20 - 30 nm宽的电子致密颗粒，单个散在于整个细胞质中。禁食小鼠的垂体前叶中，除促肾上腺皮质激素细胞外，所有细胞类型中除了散在的颗粒外，还出现明显且大量的糖原颗粒团块，促肾上腺皮质激素细胞似乎不含糖原。在含有淀粉酶培养基中孵育的垂体前叶细胞中无糖原颗粒。我们的结果表明，在小鼠垂体前叶细胞中：1）G6Pase的磷酸水解活性是内质网可靠的细胞化学标记物；2）内质网在形态和细胞化学上与高尔基体的顺面相关，但与反面或GERL无关；3）一些葡萄糖 - 6 - 磷酸，可能是体内G6Pase的底物，可能间接来源于糖原储备；4）禁食期间G6Pase活性和糖原储存的调节可能反映能量代谢的改变。
