Eid Refaat A, Al-Shraim Mubarak, Al-Falki Yahya, Al-Emam Ahmed, Alsabaani Nasser A, Radad Khaled
a Department of Pathology, College of Medicine , King Khalid University , Abha , Saudi Arabia.
b Department of Surgery, Ophthalmology Division, College of medicine , King Khalid University , Abha , Saudi Arabia.
Ultrastruct Pathol. 2018 Jul-Aug;42(4):358-364. doi: 10.1080/01913123.2018.1488790. Epub 2018 Jun 28.
Injury to lacrimal glands represents a major health problem after radiation therapy of the head and neck malignancies. Accordingly, this study aimed to investigate significant ultrastructural changes of lacrimal glands and some of their underlying mechanisms following the exposure to different fractionated doses of irradiation. In this study, 28 Sprague Dawley (SD) rats were assigned to four groups (seven rats each): Group I acted as control and received no irradiation. Groups II-IV received fractionated irradiation of 5 Gy (100 cGy/fraction daily for 5 days), 9 Gy (300 cGy/fraction daily for 3 days), and 20 Gy (one fraction), respectively. One month after the experiment, examination of lacrimal glands with transmission electron microscopy (TEM) demonstrated dose-dependent ultrastructural changes in the lacrimal acinar and intralobular ductal epithelial cells. In the acinar cells, there were swollen rough endoplasmic reticulum, irregularly shaped nuclei with chromatin condensation, mitochondrial damage, and retention of secretory granules. Intaralobular ductal epithelial cells showed loss of surface microvilli and damage to mitochondria. In addition to the potential direct effects of irradiation on lacrimal acinar and intralobular ductal epithelial cells, damage to blood vessels and nerve endings seemed to mediate some of the underlying mechanisms of these irradiation-induced ultrastructural changes. In conclusion, using TEM reveals that lacrimal gland is highly sensitive to even small doses of irradiation therapy; in addition, swelling of rough endoplasmic reticulum and aberrant nuclei are the most encountered structural changes. Damage to blood vessels and nerve endings might mediate some of the underlying mechanisms of irradiation-induced secondary injury in lacrimal glands.
泪腺损伤是头颈部恶性肿瘤放射治疗后的一个主要健康问题。因此，本研究旨在探讨泪腺在接受不同分割剂量照射后的显著超微结构变化及其一些潜在机制。在本研究中，将28只Sprague Dawley（SD）大鼠分为四组（每组7只）：第一组作为对照组，不接受照射。第二至四组分别接受5 Gy（每天100 cGy，共5天）、9 Gy（每天300 cGy，共3天）和20 Gy（单次照射）的分割照射。实验1个月后，用透射电子显微镜（TEM）检查泪腺，结果显示泪腺腺泡和小叶内导管上皮细胞出现剂量依赖性超微结构变化。在腺泡细胞中，有粗面内质网肿胀、核形状不规则且染色质浓缩、线粒体损伤以及分泌颗粒潴留。小叶内导管上皮细胞表现为表面微绒毛丧失和线粒体损伤。除了照射对泪腺腺泡和小叶内导管上皮细胞的潜在直接影响外，血管和神经末梢的损伤似乎介导了这些照射诱导的超微结构变化的一些潜在机制。总之，使用TEM显示泪腺对即使小剂量的放射治疗也高度敏感；此外，粗面内质网肿胀和细胞核异常是最常见的结构变化。血管和神经末梢的损伤可能介导了泪腺照射诱导的继发性损伤的一些潜在机制。
