Paiva Elder A S, Oliveira Denise M T, Machado Silvia R
Departamento de Botânica, Instituto de Ciências Biológicas, UFMG, Belo Horizonte, Minas Gerais, Brazil.
An Acad Bras Cienc. 2008 Sep;80(3):455-65. doi: 10.1590/s0001-37652008000300007.
Discrepant and incomplete interpretations of fruits of Pterodon have been published, especially on the structural interpretation of the pericarp portion that remain attached to the seed upon dispersal. The present work clarified these doubts and analyzed ultrastructural aspects of the Pterodon emarginatus diaspores using light and transmission electron microscopes. Cell divisions are prevalent among the initial phases of development, and the subadaxial and adaxial meristems form the fibrous inner mesocarp and the endocarp composed of multi-seriate epidermis, respectively. At the median mesocarp, numerous secretory ducts differentiate between the lateral bundles, by lytic process. After lysis of the central cells and the formation of the lumen, the ducts show unistratified secretory epithelium with dense cells; oil droplets are observed on the secretory epithelium and the subadjacent tissues. At maturity, the uniseriate exocarp and the outer mesocarp slough off in an irregular fashion, leaving the diaspore composed of a papery and brittle wing linked to a seed chamber that includes the median mesocarp composed of lignified cells, bordering vascular bundles and many secretory ducts whose epithelial cells develop large vacuoles that accumulate oleoresins. The Pterodon emarginatus fruit is a cryptosamara.
关于翼豆属果实的解释存在差异且不完整，尤其是在对果实中果皮部分的结构解释上，果皮在果实传播时仍附着于种子。本研究澄清了这些疑问，并使用光学显微镜和透射电子显微镜分析了翼豆属边缘翼豆（Pterodon emarginatus）果实的超微结构特征。细胞分裂在发育初期很普遍，近轴面和远轴面的分生组织分别形成纤维状的内果皮中层和由多层表皮组成的内果皮。在中果皮中部，通过溶蚀过程，在侧生维管束之间分化出许多分泌道。中央细胞溶解并形成管腔后，分泌道显示出具有致密细胞的单层分泌上皮；在分泌上皮和相邻组织中观察到油滴。成熟时，单层外果皮和外果皮中层不规则脱落，果实由薄而脆的翅与种子室相连组成，种子室包括由木质化细胞组成的中果皮中层，其边缘有维管束和许多分泌道，分泌道的上皮细胞形成大液泡，积累油树脂。翼豆属边缘翼豆的果实为隐翅果。
