Strum J M, Latham P S, Schmidt M L, McDowell E M
Virchows Arch B Cell Pathol Incl Mol Pathol. 1985;50(1):43-57.
The effects of vitamin A deprivation on the tracheal epithelium of young hamsters were investigated. Colchicine was administered 6 h prior to death to induce metaphase arrest, thus making it possible to quantify the mitotic rates of basal cells and secretory (mucous) cells in the epithelium. Blood samples were taken from all hamsters, and liver samples from some, in order to measure serum and tissue levels of vitamin A. Age-matched controls were compared with the following groups of hamsters maintained on a vitamin A deficient diet: pre weight plateau animals (those gaining weight), weight plateau-early weight loss animals (those maintaining approximately the same weight for 3 or 4 days, followed in some cases by a loss of weight for 3 or 4 days), and prolonged weight loss animals (those showing a loss of weight for 5 or more days). Four week old hamsters in a pre weight plateau had undetectable amounts of vitamin A in their livers and declining levels in their serum, whereas 4 1/2 week old hamsters still gaining weight had barely detectable levels of vitamin A in their serum. Nevertheless, the tracheal epithelium of these animals was not different from controls in appearance, proportions of different cell types, mitotic rates of secretory and basal cells, or in the number of cells per millimeter of basement membrane (cell density). Vitamin A was undetectable in the serum and livers of hamsters in the weight plateau-early weight loss stage. At this time the tracheal epithelium showed minimal morphological change, with small focal areas of epidermoid metaplasia in some animals. The tracheas of animals in early weight loss were smaller than tracheas in the control group, and there was a trend towards an increase in the number of epithelial cells per millimeter basement membrane. Cell types in the minimally changed epithelium appeared nearly normal, but there was an increase in the proportion of basal cells, and an absence (or near absence) of division in both basal and secretory cells. Tracheal rings from hamsters in the prolonged weight loss stage were lined by a cornifying metaplastic epidermoid epithelium. Our findings demonstrate that barely detectable levels of vitamin A in the serum are sufficient to maintain normal growth and differentiation of hamster tracheal epithelium (late pre weight plateau stage). When vitamin A serum levels fall below detectable limits the animals enter the weight plateau-early weight loss stage. This stage is accompanied by an inhibition of tracheal epithelial cell growth, although nearly normal cellular differentiation is maintained.(ABSTRACT TRUNCATED AT 400 WORDS)
研究了维生素A缺乏对幼年仓鼠气管上皮的影响。在处死前6小时给予秋水仙碱以诱导中期停滞，从而能够量化上皮中基底细胞和分泌（黏液）细胞的有丝分裂率。从所有仓鼠采集血样，从部分仓鼠采集肝样，以测定血清和组织中的维生素A水平。将年龄匹配的对照组与以下几组维持在维生素A缺乏饮食的仓鼠进行比较：体重增加前的动物（体重增加的仓鼠）、体重平稳期-早期体重减轻的动物（体重维持约3或4天不变，某些情况下随后体重减轻3或4天的仓鼠）以及长期体重减轻的动物（体重减轻5天或更长时间的仓鼠）。处于体重增加前阶段的4周龄仓鼠肝脏中维生素A含量无法检测到，血清中维生素A水平下降，而仍在体重增加的4.5周龄仓鼠血清中维生素A水平 barely detectable（勉强可检测到）。然而，这些动物的气管上皮在外观、不同细胞类型比例、分泌细胞和基底细胞的有丝分裂率或每毫米基底膜的细胞数量（细胞密度）方面与对照组没有差异。处于体重平稳期-早期体重减轻阶段的仓鼠血清和肝脏中无法检测到维生素A。此时气管上皮显示出最小的形态变化，一些动物出现小的局灶性表皮样化生区域。早期体重减轻动物的气管比对照组的气管小，每毫米基底膜的上皮细胞数量有增加的趋势。变化最小的上皮中的细胞类型看起来几乎正常，但基底细胞比例增加，基底细胞和分泌细胞均无（或几乎无）分裂。长期体重减轻阶段仓鼠气管环内衬有角质化化生的表皮样上皮。我们的研究结果表明血清中勉强可检测到水平的维生素A足以维持仓鼠气管上皮的正常生长和分化（体重增加前后期阶段）。当血清维生素A水平降至可检测极限以下时，动物进入体重平稳期-早期体重减轻阶段。这个阶段伴随着气管上皮细胞生长的抑制，尽管细胞分化仍维持在接近正常的水平。（摘要截断于400字）
