Cell proliferation in the midgut during the post-embryonic development of Aedes aegypti

The midgut epithelium of mosquitos is constituted by different cell types, such as the digestive cells, responsible for digestion and nutrient absorption and the regenerative cells. During the metamorphosis, the larval midgut epithelium is replaced by the adult one that arises from regenerative cells differentiation. In the present work we investigated the midgut epithelium modifications, including cell proliferation, during the post-embryonic development of the Aedes aegypti. Midguts from larvae (fourth instar, L4), pupae (24 and 48h after pupation) and adult female (newly emerged) were dissected in PBS and fixed with formaldehyde 4%. Samples were dehydrated in ethanol series and embedded in historesin for sectioning. Sections were stained with hematoxylin and eosin. Samples were also washed in PBST following incubation in the anti-histone H3 antibody (mitosis marker) followed by incubation in anti-mouse IgG-FITC. The cytoskeleton was stained with rhodamine phaloidin and the whole mounts were observed under a confocal laser microscope Zeiss LSM 510. The larval epithelium degenerates and it is rebuilt during the pupation following regenerative cells differentiation. The H3-immunoreactive regenerative cell nuclei were found in the L4 and at the first 24h of pupation, suggesting that regenerative cell proliferation occurs at the end of larval period and during the metamorphosis. The blood digestion and nutrient absorption occur in the midgut of mosquitos. Also, it is a target of pathogen infections. The tracking of regenerative cell proliferation during post-embryonic development can generate new information for the better understanding of the biology of the digestive tract of A. aegypti. Financial support: Fapemig and CNPq.