Cardoso W V, Stewart L G, Pinkerton K E, Ji C, Hook G E, Singh G, Katyal S L, Thurlbeck W M, Plopper C G
Department of Pathology, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Am J Physiol. 1993 Jun;264(6 Pt 1):L543-52. doi: 10.1152/ajplung.1993.264.6.L543.
One function of the nonciliated (Clara) cells of bronchiolar epithelium is to synthesize, store, and release small-molecular-mass (6-12 kDa) secretory proteins or Clara cell secretory protein (CCSP). This study compares the emergence of this secretory function during Clara cell differentiation in rabbits and rats. Lungs of fetal and postnatal animals were evaluated by ultrastructural morphometry and immunohistochemistry. Secretory granules were rarely seen in perinatal animals and increased to adult levels of abundance earlier in rats (1 wk postnatal) than in rabbits (3-4 wk). In contrast, rough endoplasmic reticulum was abundant in perinatal animals and decreased with age. Antibodies raised against CCSP revealed little CCSP in fetal animals; however, after birth CCSP increased to adult levels earlier in rats (1 wk postnatal) than in rabbits (3 wk). We conclude that the maturation of Clara cell secretory function 1) occurs postnatally, 2) involves a decrease in biosynthetic organelles, 3) shows close association between CCSP expression and secretory granule abundance, and 4) varies by species in timing and cellular abundance of biosynthetic machinery.
细支气管上皮的无纤毛（克拉拉）细胞的一项功能是合成、储存和释放小分子质量（6 - 12 kDa）的分泌蛋白，即克拉拉细胞分泌蛋白（CCSP）。本研究比较了兔和大鼠克拉拉细胞分化过程中这种分泌功能的出现情况。通过超微结构形态计量学和免疫组织化学对胎儿及出生后动物的肺进行评估。围产期动物中很少见到分泌颗粒，其丰度在大鼠（出生后1周）比在兔（3 - 4周）更早增加到成年水平。相反，围产期动物中粗面内质网丰富，且随年龄增长而减少。针对CCSP产生的抗体显示胎儿动物中CCSP很少；然而，出生后CCSP在大鼠（出生后1周）比在兔（3周）更早增加到成年水平。我们得出结论，克拉拉细胞分泌功能的成熟：1）发生在出生后，2）涉及生物合成细胞器的减少，3）显示CCSP表达与分泌颗粒丰度密切相关，4）在生物合成机制的时间和细胞丰度方面因物种而异。
