Brandsma A E, ten Have-Opbroek A A, Vulto I M, Molenaar J C, Tibboel D
Department of Pulmonology, Universities of Leiden, The Netherlands.
Exp Lung Res. 1994 Nov-Dec;20(6):491-515. doi: 10.3109/01902149409031734.
The aim of the present study was to compare the architecture and alveolar epithelial cell composition of the pulmonary acinus in hypoplastic and normal fetal rat lungs. For this purpose, a rat model of pulmonary hypoplasia in association with congenital diaphragmatic hernia (CDH) induced by Nitrofen (100 mg on day 10 of pregnancy) was studied. Sections (5 microns) from lungs of control and Nitrofen-exposed fetal Sprague Dawley rats with or without CDH aged 18-22 days (vaginal plug on day 1, birth on day 23) were stained with hematoxylin and eosin. To identify developing alveolar epithelial cells, sections were incubated with anti-surfactant protein A (SP-A; rabbit anti-mouse) or preimmunization serum (indirect immunofluorescence). On days 18 and 19, control lungs and exposed lungs from fetuses with and without CDH looked similar (pseudoglandular stage of lung development). The prospective pulmonary acinus consisted of acinar tubules with small round lumens, lined by cuboid, fluorescent type II cells. Morphometric analysis on day 19 showed significantly smaller lung volumes and lung tissue volumes after Nitrofen exposure. On day 20 (canalicular stage), some tubules were slightly dilated and lined by cuboid and thinner fluorescent cells; these dilated tubules were less numerous in lungs from exposed fetuses with CDH. On days 21 and 22 (saccular stage), the saccular lining consisted of cuboid to thin fluorescent cells in exposed lungs from fetuses with and without CDH, and fluorescent (low) cuboid cells interspersed with dark zones (type I cell areas) in control lungs. In the exposed lungs from fetuses with CDH, the lumens of all airspaces were frequently slit-like, and the septa were thicker. These phenomena gave the lungs a primitive, compact aspect. Morphometric analysis on day 22 showed smaller lung volumes and lung tissue volumes, smaller airspace/tissue ratios, smaller epithelial surface areas, and more type II cells per surface area in Nitrofen-exposed lungs than in normal control lungs. The results suggest that Nitrofen-exposed, and thus hypoplastic, fetal rat lungs are retarded with respect to the differentiation of cuboid type II cells into squamous type I cells whether or not CDH is present, and with respect to the development of the future airspaces between days 20 and 22 if CDH is present.
本研究的目的是比较发育不全和正常胎鼠肺脏中肺腺泡的结构及肺泡上皮细胞组成。为此，研究了一种由硝唑芬（妊娠第10天给予100毫克）诱导的与先天性膈疝（CDH）相关的肺发育不全大鼠模型。对18 - 22日龄（第1天见阴栓，第23天出生）的对照胎鼠和暴露于硝唑芬的胎鼠（无论有无CDH）的肺脏制作5微米厚的切片，用苏木精和伊红染色。为识别发育中的肺泡上皮细胞，切片与抗表面活性蛋白A（SP - A；兔抗小鼠）或免疫前血清一起孵育（间接免疫荧光法）。在第18天和第19天，对照胎鼠肺脏以及有和无CDH的暴露胎鼠肺脏看起来相似（肺发育的假腺期）。预期的肺腺泡由具有小圆形管腔的腺泡小管组成，内衬立方形、发荧光的II型细胞。第19天的形态计量分析显示，硝唑芬暴露后肺体积和肺组织体积显著减小。在第20天（小管期），一些小管略有扩张，内衬立方形且较薄的发荧光细胞；在有CDH的暴露胎鼠肺脏中，这些扩张的小管数量较少。在第21天和第22天（囊状期），有和无CDH的暴露胎鼠肺脏的囊状内衬由立方形至薄的发荧光细胞组成，而对照肺脏中发荧光（低）的立方形细胞与暗区（I型细胞区域）相间分布。在有CDH的暴露胎鼠肺脏中，所有气腔的管腔常呈裂隙状，且间隔更厚。这些现象使肺脏呈现出原始、致密的外观。第22天的形态计量分析显示，与正常对照肺脏相比，硝唑芬暴露的肺脏肺体积和肺组织体积更小，气腔/组织比更小，上皮表面积更小，且每表面积的II型细胞更多。结果表明，无论有无CDH，暴露于硝唑芬因而发育不全的胎鼠肺脏在立方形II型细胞向扁平I型细胞的分化方面均延迟，并且如果存在CDH，则在第20天至22天期间未来气腔的发育方面也延迟。
