Vommaro Maria Luigia, Kurtz Joachim, Giglio Anita
Department of Biology, Ecology and Earth Science, University of Calabria, 87036 Rende, Italy.
Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany.
Insects. 2021 May 8;12(5):423. doi: 10.3390/insects12050423.
The immunocompetence of the mealworm beetle has been well investigated at molecular and physiological levels, but information on morphological and functional characteristics of its immune cells (haemocytes) is still scarce and fragmentary. This study provides an updated overview of the morphology of circulating immune cells from mealworm beetle adults, using light and transmission electron microscopy. Based on their affinities for May-Grünwald Giemsa stain, haemocytes were defined as either eosinophilic, basophilic or neutral. Ultrastructural descriptions allowed to detect four main cell types in the haemolymph: prohaemocytes, plasmatocytes, granular cells and oenocytoids. The morphological plasticity of haemocytes and the evidence of mitotic circulating cells, intermediate cell stages, as well as autophagic activities suggest haemocyte proliferation, turnover and transdifferentiation as constantly active processes in the haemolymph. Cytochemical tests revealed differences in the distribution of carbohydrates among cell types underling the great plasticity of the immune response and the direct involvement of circulating immune cells in the resource allocation. In addition, our results provide a detailed morphological description of vesicle trafficking, macro- and microautophagy, apoptotic and necrotic processes, confirming the suitability of haemocytes as a model for studying evolutionarily conserved cellular mechanisms.
黄粉虫的免疫能力已在分子和生理水平上得到充分研究，但关于其免疫细胞（血细胞）的形态和功能特征的信息仍然稀缺且不完整。本研究利用光学显微镜和透射电子显微镜，对黄粉虫成虫循环免疫细胞的形态进行了最新概述。根据血细胞对美-姬姆萨染色的亲和力，血细胞被定义为嗜酸性、嗜碱性或中性。超微结构描述揭示了血淋巴中的四种主要细胞类型：原血细胞、浆细胞、颗粒细胞和类绛色细胞。血细胞的形态可塑性以及有丝分裂循环细胞、中间细胞阶段和自噬活动的证据表明，血细胞增殖、更新和转分化是血淋巴中持续活跃的过程。细胞化学测试揭示了不同细胞类型之间碳水化合物分布的差异，这表明免疫反应具有很大的可塑性，循环免疫细胞直接参与了资源分配。此外，我们的结果提供了囊泡运输、巨自噬和微自噬、凋亡和坏死过程的详细形态学描述，证实了血细胞作为研究进化上保守的细胞机制模型的适用性。
