Background

Each eccrine sweat gland (ESG) is a single-tubular structure with a central lumen, and the formation of hollow lumen in the initial solid cell mass is a key developmental process. To date, there are no reports on the mechanism of native ESG lumen formation.

Methods

To investigate the lumen morphogenesis and the lumen formation mechanisms of Sprague-Dawley (SD) rat ESGs, SD rat hind-footpads at E20.5, P1–P5, P7, P9, P12, P21, P28 and P56 were obtained. The lumen morphogenesis of ESGs was examined by HE staining and immunofluorescence staining for polarity markers. The possible mechanisms of lumen formation were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay and autophagy marker LC3B immunofluorescence staining, and further explored by ouabain intervention experiment.

Results

In SD rat ESGs, the microlumen was formed at P1, and the small intact lumen with apical-basal polarity appeared at P3. The expression of apical marker F-actin, basal marker Laminin, basolateral marker E-cadherin was consistent with the timing of lumen formation of SD rat ESGs. During rat ESG development, apoptosis and autophagy were not detected. However, inhibition of Na⁺-K⁺-ATPase (NKA) with ouabain resulted in decreased lumen size, although neither the timing of lumen formation nor the expression of polarity proteins was altered.

Conclusions

Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of SD rat ESGs. NKA-regulated fluid accumulation drives lumen expansion.

中文翻译：

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上皮极性驱动的膜分离而非空化调节大鼠小汗腺的管腔形成

背景

每个小汗腺（ESG）都是一个具有中央管腔的单管状结构，在最初的固体细胞团中中空管腔的形成是一个关键的发育过程。迄今为止，还没有关于天然 ESG 管腔形成机制的报道。

方法

为了研究 Sprague-Dawley (SD) 大鼠 ESG 的管腔形态发生和管腔形成机制，获得了 E20.5、P1–P5、P7、P9、P12、P21、P28 和 P56 处的 SD 大鼠后足垫。通过 HE 染色和极性标记的免疫荧光染色检查 ESG 的管腔形态发生。通过末端脱氧核苷酸转移酶dUTP缺口末端标记（TUNEL）凋亡实验和自噬标记物LC3B免疫荧光染色检测管腔形成的可能机制，并通过哇巴因干预实验进一步探讨。

结果

在SD大鼠ESG中，微管腔在P1形成，而具有顶底极性的小完整管腔在P3出现。顶端标志物F-actin、基底标志物Laminin、基底外侧标志物E-cadherin的表达与SD大鼠ESG管腔形成时间一致。在大鼠ESG发育过程中，未检测到细胞凋亡和自噬。然而，用哇巴因抑制Na ⁺ -K ⁺ -ATP酶（NKA）会导致管腔尺寸减小，尽管管腔形成的时间和极性蛋白的表达都没有改变。

结论

上皮极性驱动的膜分离而非空化调节 SD 大鼠 ESG 的管腔形成。NKA 调节的液体积聚驱动管腔扩张。