A bacteriocyte (Greek for bacteria cell), also known as a mycetocyte, is a specialized adipocyte found primarily in certain insects such as aphids, tsetse flies, German cockroaches, weevils, and ants.

Horizontal transmission or infection does not typically appear because insects with bacteriocytes depend so significantly on their symbiotic relationships to survive.

One theory is that the microorganisms circulating in the hemolymph of the mother migrate to a posterior region of the offspring blastula containing enlarged follicle cells.

Other studies suggest that symbionts are directly transferred from the maternal bacteriocyte to the follicular region of the blastula through exocytic and endocytic transport.

A newer hypothesis suggests that a membranous conduit forms between the maternal bacteriocyte and blastula which acts as a bridge for symbionts.

This form of bacteriocyte death is also nonapoptotic, based on the irregular shape of the adult nucleus as well as a lack of chromatin condensation during degeneration and other characteristic features.

Aphids, on the other hand, are closely evolutionarily tied to bacterial endosymbiosis resulting in a more complicated form of cell death.

The microorganisms housed in these specialized cells produce essential nutrients for their hosts in exchange for an enclosed environment to live.

The health of these endosymbionts is crucial for the host's biology as their presence changes the balance of amino acid metabolism and mitochondrial phosphorylation.

[2] Because of this nutritional imbalance, bacteriocytes are more prevalent in insects that utilize diets consisting of an excess of one compound while lacking some nutrients, like amino acids and proteins.

[1] While some endosymbionts directly provide their hosts with food, others secrete enzymes to help aid in digestion of materials the insect cannot break down itself such as wood.

[8] Development of aphid (Acyrthosiphon pisum) bacteriocytes has been studied with the host cells that contain the endosymbiotic bacteria, Buchnera aphidicola.