Freeze tolerance in turtles: visual analysis by microscopy and magnetic resonance imaging.
Freeze tolerance in turtles: visual analysis by microscopy and magnetic resonance imaging.
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海龟的耐冻性：通过显微镜和磁共振成像进行视觉分析。
DOI：
10.1152/ajpregu.1994.267.4.r1078
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Storey,KB
中科院分区：
文献类型：
--
作者：
Rubinsky,B;Hong,JS;Storey,KB
采用两种视觉技术分析了耐冻彩龟幼龟的自然冻融模式。使用肝脏、心脏和骨骼肌切片的定向凝固加光学显微镜来比较在-4摄氏度（体内可存活温度）和-20摄氏度（不可存活）下的冷冻。在-4摄氏度时，组织在扩张的细胞外和血管空间中显示出大量的冰，占据总组织体积的36%（肝脏）和61%（肌肉）。细胞在-4 ℃时收缩，但胞内水仍然存在;然而，在-20 ℃时，细胞几乎没有自由水的迹象。肝脏显微照片显示，新的球形壳的水与细胞内的颗粒（显然是糖原颗粒），这表明一个非依数的细胞保水的方法。质子磁共振成像用于无创分析冷冻和解冻在完整的动物。图像显示，冷冻以定向方式通过身体传播，首先在器官外空间形成冰（例如，腹腔、脑室）。然而，整个身体核心的融化是均匀的，器官比周围的器官外冰融化得更快。
Two visual techniques were used to analyze the patterns of natural freezing and thawing in freeze-tolerant hatchling painted turtles Chrysemys picta marginata. Directional solidification plus light microscopy of liver, heart, and skeletal muscle slices was used to compare freezing at -4 degrees C (a survivable temperature in vivo) and -20 degrees C (not survivable). At -4 degrees C tissues showed large amounts of ice in expanded extracellular and vascular spaces, occupying 36% (liver) and 61% (muscle) of total tissue volume. Cells at -4 degrees C were shrunken, but intracellular water remained; at -20 degrees C, however, cells showed little evidence of free water. Liver micrographs showed novel spherical shells of water associated with intracellular particles (apparently glycogen granules) suggesting that a noncolligative method of cell water retention was employed. Proton magnetic resonance imaging was used for noninvasive analysis of freezing and thawing in the intact animal. Images showed that freezing propagated in a directional manner through the body with ice formed first in extraorgan spaces (e.g., abdominal cavity, brain ventricles). However, thawing occurred uniformly throughout the body core, and organs melted more rapidly than the extraorgan ice surrounding them.