Plate bodies are facultative organelles occasionally described in the adult lungs of various species, including sheep and goat. They consist of multiple layers of plate-like cisterns with an electron dense middle bar. The present study was performed to elucidate the three-dimensional (3D) characteristics of this organelle and its presumed function in surfactant protein A (SP-A) biology. Archived material of four adult goat lungs and PFA-fixed lung samples of two adult sheep lungs were used for the morphological and immunocytochemical parts of this study, respectively. 3D imaging was performed by electron tomography and focused ion beam scanning electron microscopy (FIB-SEM). Immuno gold labeling was used to analyze whether plate bodies are positive for SP-A. Transmission electron microscopy revealed the presence of plate bodies in three of four goat lungs and in both sheep lungs. Electron tomography and FIB-SEM characterized the plate bodies as layers of two up to over ten layers of membranous cisterns with the characteristic electron dense middle bar. The membranes of the plates were in connection with the rough endoplasmic reticulum and showed vesicular inclusions in the middle of the plates and a vesicular network at the sides of the organelle. Immuno gold labeling revealed the presence of SP-A in the vesicular network of plate bodies but not in the characteristic plates themselves. In conclusion, the present study clearly proves the connection of plate bodies with the rough endoplasmic reticulum and the presence of a vesicular network as part of the organelle involved in SP-A trafficking.

板体是在各种物种（包括绵羊和山羊）的成年肺部中偶尔出现的兼性细胞器。它们由多层板状水池组成，中间有一个电子密集条。本研究旨在阐明该细胞器的三维 (3D) 特征及其在表面活性蛋白 A (SP-A) 生物学中的推测功能。本研究的形态学和免疫细胞化学部分分别使用了四个成年山羊肺的存档材料和两个成年绵羊肺的 PFA 固定肺样本。通过电子断层扫描和聚焦离子束扫描电子显微镜 (FIB-SEM) 进行 3D 成像。采用免疫金标记分析板体是否呈SP-A阳性。透射电子显微镜显示在四个山羊肺中的三个和两个绵羊肺中存在板状体。电子断层扫描和 FIB-SEM 将板体表征为两层至十多层膜池，具有特征电子密集的中间条。板的膜与粗面内质网相连，并在板的中部显示出囊泡内含物，在细胞器的侧面显示出囊泡网络。免疫金标记显示板体的囊泡网络中存在 SP-A，但特征板本身不存在。总之，本研究清楚地证明了板体与粗面内质网的联系，以及作为参与 SP-A 运输的细胞器一部分的囊泡网络的存在。