A novel site of haematopoiesis and appearance and dispersal of distinct haemocyte types in the Manduca sexta embryo (Insecta, Lepidoptera)

• Published in: Developmental and comparative immunology 2020-10, Vol.111, p.103722-103722, Article 103722
• Main Authors: von Bredow, Yvette M., von Bredow, Christoph-Rüdiger, Trenczek, Tina E.
• Format: Article
• Language: English
• Subjects: (Pro–)phenol oxidase containing embryonic oenocytoids; Abdominal hemocyte cluster; Embryonic insect haematopoiesis; Embryonic plasmatocytes; Tobacco hornworm (Manduca sexta) embryonic hemocyte types; Transient haematopoietic sites
• ISSN: 0145-305X; 1879-0089
• DOI: 10.1016/j.dci.2020.103722

With a set of haemocyte specific markers novel findings on haematopoiesis in the Manduca sexta embryo are presented. We identify a hitherto unknown paired haematopoietic cluster, the abdominal haemocyte cluster in abdominal segment 7 (A7–HCC). These clusters are localised at distinct positions and are established at around katatrepsis. Later in embryogenesis, the A7–HCCs disintegrate, thereby releasing numerous embryonic plasmatocytes which disperse both anteriorly and posteriorly. These cells follow stereotypic migration routes projecting anteriorly. The thoracic larval haematopoietic organs are established at around midembryogenesis. We identify embryonic oenocytoids in the M. sexta embryo for the first time. They appear in the head region roughly at the same time as the A7–HCCs occur and successively disperse in the body cavity during development. Localisation of the prophenoloxidase (proPO) mRNA and of the proPO protein are identical. Morphological, cytometric and antigenic traits show three independently generated haemocyte types during embryogenesis. •Three haemocyte types were recognised by specific markers in the M. sexta embryo.•Transient haematopoietic sites of embryonic plasmatocytes in the abdominal segment 7.•Oenocytoids occur in the prekatatreptic embryo head and subsequently disperse.