Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.
PLoS One. 2013;8(2):e57384. doi: 10.1371/journal.pone.0057384. Epub 2013 Feb 25.
Hemocytes are the first line of defense of the immune system in invertebrates, but despite their important role and enormous potential for the study of gene-environment relationships, research has been impeded by a lack of consensus on their classification. Here we used flow cytometry combined with histological procedures, histochemical reactions and transmission electron microscopy to characterize the hemocytes from the oyster Crassostrea rhizophorae. Transmission electron microscopy revealed remarkable morphological characteristics, such as the presence of membranous cisternae in all mature cells, regardless of size and granulation. Some granular cells contained many cytoplasmic granules that communicated with each other through a network of channels, a feature never previously described for hemocytes. The positive reactions for esterase and acid phosphatase also indicated the presence of mature cells of all sizes and granule contents. Flow cytometry revealed a clear separation in complexity between agranular and granular populations, which could not be differentiated by size, with cells ranging from 2.5 to 25 µm. Based on this evidence we suggest that, at least in C. rhizophorae, the different subpopulations of hemocytes may in reality be different stages of one type of cell, which accumulates granules and loses complexity (with no reduction in size) as it degranulates in the event of an environmental challenge.
血细胞是无脊椎动物免疫系统的第一道防线，但尽管它们在研究基因-环境关系方面具有重要作用和巨大潜力，但由于缺乏对其分类的共识，研究一直受到阻碍。在这里，我们使用流式细胞术结合组织学程序、组织化学反应和透射电子显微镜来描述来自牡蛎 Crassostrea rhizophorae 的血细胞。透射电子显微镜显示出显著的形态特征，例如所有成熟细胞（无论大小和颗粒度如何）都存在膜内质网。一些颗粒细胞含有许多细胞质颗粒，这些颗粒通过一个通道网络相互连通，这是以前从未在血细胞中描述过的特征。酯酶和酸性磷酸酶的阳性反应也表明存在所有大小和颗粒内容物的成熟细胞。流式细胞术清楚地区分了无颗粒和颗粒群体之间的复杂性，而大小无法区分这两个群体，细胞大小范围为 2.5 至 25 µm。基于这些证据，我们认为，至少在 C. rhizophorae 中，不同的血细胞亚群实际上可能是同一类型细胞的不同阶段，这些细胞会积累颗粒并随着脱颗粒而失去复杂性（大小没有减小），以应对环境挑战。
