Cai F, Dickson D H
Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Nova Scotia, Canada.
Curr Eye Res. 1994 Aug;13(8):611-7. doi: 10.3109/02713689408999895.
Myeloid bodies (MBs) are multi-lamellar membrane structures which are widely distributed in the retinal pigment epithelium (RPE) of lower vertebrates. The functional significance of these organelles is not known, but they are believed to be associated with lipid processing in the retina. To determine the nature of the daily changes which occur in MBs, and to ascertain the best sampling time for MB isolation as a prelude to the biochemical characterization of these organelles, this study has assessed the occurrence and area density of MBs in the leopard frog (Rana pipiens) over a daily light-dark cycle. Eye tissues from light-entrained (12L:12D) frogs were sampled at 1, 4, 7, 10 hr after both lights-on and lights-off (n = 5). In addition, to determine whether MB formation is a circadian or light-driven event, the effect of a period of prolonged darkness on MB formation was also examined by maintaining frogs in the dark for an additional 1, 4, 7, and 10 hr at the end of a normal dark phase (n = 5). The number and area density as a percentage of total RPE cell area (area %) for phagosomes (PGs), oil droplets (ODs) and MBs were determined morphometrically using light and electron microscopy. Data were analyzed by a nested analysis of variance. Results indicated that: 1) PG numbers were elevated significantly following lights-on and were reduced almost to nil in the late dark period.(ABSTRACT TRUNCATED AT 250 WORDS)
髓样小体（MBs）是多片层膜结构，广泛分布于低等脊椎动物的视网膜色素上皮（RPE）中。这些细胞器的功能意义尚不清楚，但人们认为它们与视网膜中的脂质处理有关。为了确定MBs中每日变化的性质，并确定作为这些细胞器生化特征前奏的MB分离的最佳采样时间，本研究评估了豹蛙（Rana pipiens）在每日昼夜循环中MBs的发生率和面积密度。对处于光周期（12L:12D）的青蛙，在开灯和关灯后1、4、7、10小时进行眼组织采样（n = 5）。此外，为了确定MB形成是昼夜节律性事件还是光驱动事件，还通过在正常黑暗期结束时将青蛙再置于黑暗中1、4、7和10小时，研究了长时间黑暗对MB形成的影响（n = 5）。使用光学显微镜和电子显微镜通过形态计量学确定吞噬体（PGs）、油滴（ODs）和MBs的数量以及占RPE细胞总面积的百分比（面积%）。数据通过嵌套方差分析进行分析。结果表明：1）开灯后PG数量显著增加，在黑暗后期几乎降至零。
