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Abstract：
OBJECTIVE: The maternal gametophytic calyptra is critical for moss sporophyte development and ultimately sporogenesis. The calyptra has been predicted to protect the sporophyte apex, including the undifferentiated sporogenous region and seta meristem, from desiccation. We investigate the hypothesis that this waterproofing ability is due to a waxy cuticle. The idea that moss calyptrae are covered by a cuticle has been present in the literature for over a century, but, until now, neither the presence nor the absence of a cuticle has been documented for any calyptra.
METHODS: The epidermis of the calyptra, leafy gametophyte and sporophyte sporangia of the moss Funaria hygrometrica were examined using scanning and transmission electron microscopy. Thicknesses of individual cuticle layers were quantified and compared statistically. The immunochemistry antibody (LM19) specific for pectins was used to locate cell wall material within the cuticle.
RESULTS: A multi-layered cuticle is present on the calyptra of F. hygrometrica, including layers analogous to the cuticular layer, cell wall projections, electron-lucent and electron-dense cuticle proper observed in vascular plants. The calyptra rostrum has a cuticle that is significantly thicker than the other tissues examined and differs by specialized thickenings of the cuticular layer (cuticular pegs) at the regions of the anticlinal cell walls. This is the first documentation of cuticular pegs in a moss.
CONCLUSIONS: The calyptra and its associated cuticle represent a unique form of maternal care in embryophytes. This organ has the potential to play a critical role in preventing desiccation of immature sporophytes and thereby may have been essential for the evolution of the moss sporophyte.
METHODS: The epidermis of the calyptra, leafy gametophyte and sporophyte sporangia of the moss Funaria hygrometrica were examined using scanning and transmission electron microscopy. Thicknesses of individual cuticle layers were quantified and compared statistically. The immunochemistry antibody (LM19) specific for pectins was used to locate cell wall material within the cuticle.
RESULTS: A multi-layered cuticle is present on the calyptra of F. hygrometrica, including layers analogous to the cuticular layer, cell wall projections, electron-lucent and electron-dense cuticle proper observed in vascular plants. The calyptra rostrum has a cuticle that is significantly thicker than the other tissues examined and differs by specialized thickenings of the cuticular layer (cuticular pegs) at the regions of the anticlinal cell walls. This is the first documentation of cuticular pegs in a moss.
CONCLUSIONS: The calyptra and its associated cuticle represent a unique form of maternal care in embryophytes. This organ has the potential to play a critical role in preventing desiccation of immature sporophytes and thereby may have been essential for the evolution of the moss sporophyte.
摘要：
目的：母系配子体calyptra对苔藓孢子体发育和最终孢子发生至关重要。已预测calyptra可以保护孢子体顶端，包括未分化的孢子区和刚毛分生组织，从干燥。我们研究了这种防水能力是由于蜡质角质层引起的假设。苔藓被角质层覆盖的想法已经在文献中存在了一个多世纪，但是,直到现在,对于任何calyptra，都没有记录角质层的存在或不存在。
方法：calyptra的表皮，使用扫描和透射电子显微镜检查了苔藓真菌的叶状配子体和孢子体孢子囊。对各个角质层的厚度进行定量并进行统计学比较。对果胶特异性的免疫化学抗体(LM19)用于定位表皮内的细胞壁材料。
结果：在F.hygrometrica的calyptra上存在多层角质层，包括类似于角质层的层，细胞壁突起，在维管植物中观察到的电子透明和电子致密角质层。calyptra讲台的角质层比检查的其他组织明显更厚，并且在背斜细胞壁区域的角质层（角质桩）的特殊增厚有所不同。这是苔藓中角质层钉的第一份文献。
结论：calyptra及其相关的角质层代表了胚胎植物中母体护理的一种独特形式。该器官有可能在防止未成熟孢子体干燥方面发挥关键作用，因此可能对苔藓孢子体的进化至关重要。
方法：calyptra的表皮，使用扫描和透射电子显微镜检查了苔藓真菌的叶状配子体和孢子体孢子囊。对各个角质层的厚度进行定量并进行统计学比较。对果胶特异性的免疫化学抗体(LM19)用于定位表皮内的细胞壁材料。
结果：在F.hygrometrica的calyptra上存在多层角质层，包括类似于角质层的层，细胞壁突起，在维管植物中观察到的电子透明和电子致密角质层。calyptra讲台的角质层比检查的其他组织明显更厚，并且在背斜细胞壁区域的角质层（角质桩）的特殊增厚有所不同。这是苔藓中角质层钉的第一份文献。
结论：calyptra及其相关的角质层代表了胚胎植物中母体护理的一种独特形式。该器官有可能在防止未成熟孢子体干燥方面发挥关键作用，因此可能对苔藓孢子体的进化至关重要。
