The larval haematopoietic organs of Manduca sexta (Insecta, Lepidoptera): An insight into plasmatocyte development and larval haematopoiesis

• Published in: Developmental and comparative immunology Vol. 115; p. 103858
• Main Authors: von Bredow, Christoph-Rüdiger, von Bredow, Yvette M., Trenczek, Tina E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.02.2021
• Subjects: Animals; Hematopoiesis - physiology; Hemocyte differentiation; Hemocytes - physiology; Insect hematopoiesis; Larva - growth & development; Manduca - physiology; Plasmatocyte; Prohemocyte; Tobacco hornworm (Manduca sexta) hematopoietic organ; Prohemocyte; Tobacco hornworm (Manduca sexta) hematopoietic organ; Insect hematopoiesis; Plasmatocyte; Hemocyte differentiation
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2020.103858

Haematopoietic organs (HOs) in Lepidoptera are widely recognised as the source for at least two haemocyte types. With new specific markers for oenocytoids and spherule cells and a method to identify prohaemocytes, the haemocytes formed in and released by the HOs of Manduca sexta are characterised. Differentiation of HO-cells to haemocytes other than plasmatocytes and prohaemocytes neither occurs in the organ itself nor in cells released in vitro by the HOs. Differential labelling patterns evidence the existence of plasmatocyte subpopulations and prohaemocytes, which might represent a gradual differentiation of haemocytes within the organs. Prohaemocytes can be identified by PNA-labelling of the cell membrane. These prohaemocytes are found in circulation and in the HOs and are released by the organs. Circulating prohaemocytes possess characteristics for granular cells, plasmatocytes or oenocytoids while HO derived prohaemocytes share characteristics only with plasmatocytes. Ablation of the HOs diminishes the plasmatocyte and prohaemocyte number, indicating a true larval haematopoietic function. •Prohaemocytes can be identified by PNA-membrane labelling.•Circulating prohaemocytes share attributes of granular cells, oenocytoids and plasmatocytes.•Haematopoietic organs give directly rise to prohaemocytes and plasmatocytes.•Haematopoietic organs contribute to larval plasmatocyte formation.•Gradual haemocyte differentiation/maturation indicated by zonation of the haematopoietic organs.