SCANNING ELECTRON-MICROSCOPE STUDY OF THE DEVELOPING MICROVASCULATURE IN THE POSTNATAL RAT LUNG
SCANNING ELECTRON-MICROSCOPE STUDY OF THE DEVELOPING MICROVASCULATURE IN THE POSTNATAL RAT LUNG
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DOI：
10.1002/ar.1092160207
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发表时间：
1986-10-01
影响因子：
--
通讯作者：
BURRI, PH
中科院分区：
文献类型：
--
作者：
CADUFF, JH;FISCHER, LC;BURRI, PH
在出生后的生长过程中，大鼠肺的实质间隔经历了一个令人印象深刻的重组。未成熟的隔膜较厚，含有两个毛细血管层，成熟的隔膜较细，含有一个微血管网。利用Mercox铸型技术和扫描电镜，我们研究了肺毛细血管床转化的模式和时间。在出生后第三周，实质隔膜迅速成熟，以符合成人形态。然而，即使在成人肺中，仍存在未成熟状态的残余：在隔膜的基部和尖端经常发现毛细血管双层。我们的观察结果支持这样的概念，即减少干预组织，部分融合的两个毛细血管网络，和优先生长导致成熟的血管排列。真正成熟的肺泡间隔比邻接胸膜、支气管或大血管的肺泡壁显示出更密集的毛细血管网，这一事实与融合学说相一致。向非实质，毛细血管网络周围的每一个空气没有对应的融合。从定量数据可以计算出，由于肺的生长，从出生到成年，补片尺寸应增加四倍以上。然而，成年动物的肺网络比年轻动物的肺网络更密集。这意味着必须在生长过程中添加新网格。我们认为，在微血管的片状区域观察到的小孔扩大，形成新的毛细血管网。利用这种自身或插入生长的机制，不再需要单独的毛细血管段发芽以增加网络尺寸。
During postnatal growth the parenchymal septa of rat lung undergo an impressive restructuring. While immature septa are thick and contain two capillary layers, mature septa are slender and contain a single microvascular network. Using the Mercox casting technique and scanning electron microscopy, we investigated the mode and the timing of the transformation of the pulmonary capillary bed. During the third postnatal week the parenchymal septa rapidly mature to match adult morphology. Even in adult lungs, however, remnants of the immature status are present: A capillary bilayer is regularly found at the base and the tip of the septa. Our observations support the concept that reduction of intervening tissue, partial fusion of the two capillary networks, and preferential growth lead to the mature vascular arrangement. The fact that true mature interalveolar septa show a denser capillary network than alveolar walls abutting onto pleura, bronchi, or larger vessels is consonant with the fusion theory. Towards the nonparenchyma, the capillary network surroudning every airspace had no counterpart to fuse with. From quantitative data it can be calculated that owing to lung growth, mesh size should increase more than four times between birth and adult age. The adult lung network, however, is denser than the one in young animals. This means that new meshes must be added during growth. We propose that small holes observed in sheet-like regions of the microvasculature enlarge to form new capillary meshes. With this mechanisms of in-itself or intussusceptional growth, sprouting of individual capillary segments to increase network size is no longer needed.