A bacteriocyte also called a mycetocyte, is a specialized adipocyte

Adipocyte

However, in some reports and textbooks, the number of fat cell increased in childhood and adolescence. The total number is constant in both obese and lean adult...

 found in some insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

 groups such as aphid

Aphid

Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

s, tsetse flies, german cockroach

German cockroach

The German cockroach is a small species of cockroach, measuring about to long; however, they are known to get bigger. It can be tan through brown to almost black, and has two dark parallel streaks running from the head to the base of the wings. Although it has wings, it is unable to sustain flight...

es, and many others. Mycetocyte symbionts specifically include three insect groups: Cockroaches, Homoptera such as aphid, and Coleoptera such as weevils. These cells contain endosymbiotic bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 such as Buchnera

Buchnera (proteobacteria)

Buchnera aphidicola a member of the Proteobacteria, is the primary endosymbiont of aphids and has been studied in the pea aphid, Acyrthosiphon pisum. It is believed that Buchnera was once a free living gram negative ancestor similar to a modern Enterobacteriaceae such as Escherichia coli...

species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, which provide essential amino acids and other chemicals to their host. Bacteriocytes are maternally-transmitted, i.e. the mother transmits her endosymbionts to her offspring

Offspring

In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

. In some cases, the bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 are transmitted in the egg, as in Buchnera

Buchnera (proteobacteria)

Buchnera aphidicola a member of the Proteobacteria, is the primary endosymbiont of aphids and has been studied in the pea aphid, Acyrthosiphon pisum. It is believed that Buchnera was once a free living gram negative ancestor similar to a modern Enterobacteriaceae such as Escherichia coli...

; in others like Wigglesworthia, they are transmitted via milk to the developing insect embryo

Embryo

An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

.