Recent insights in the development and functions of insect hemocytes

Hemocytes mediate defense responses that are collectively referred to as cellular immunity. Here, I highlight recent progress in the study of hemocyte ontogeny and function. Studies conducted primarily in D. melanogaster, mosquitoes, and Lepidoptera identify a number of transcription factors and signaling pathways that regulate hemocyte differentiation and proliferation. Single-cell RNA sequencing studies identify genes that distinguish transitional states in different hemocyte populations and changes that occur during immune responses. Several new studies expand the understanding of the functions of sessile hemocytes. Recent results also enhance understanding of the signaling pathways that regulate hemocyte functions.