Abstract:  The body of insects consists of a series of appendages, including the dorsal and ventral appendages. Particularly, the ventral limbs exhibit great diversity. Here, we present a brief review of the expression, functions, and regulatory interactions of the genes related to the development of the ventral limbs. On one hand, the ventral limbs, as a whole, are controlled by the Hox gene and morphogens genes (Dpp/Wg). Hox genes control whether there are ventral limbs on certain segment. Through the formation of concentration gradients of their expressed products, Dpp/Wg regulates the development of entire vental limbs. Both of them are irreplaceable for the development of the vental limbs. On the other hand, the proximal, intermediate and distal portions are controlled by the corresponding segmental special factors, respectively. For instance, hth, tsh and al mainly control the development of the proximal portion. Dac regulates the intermediate portion by the interaction of the Dll and Dpp/Wg. Bab, Dll and Lim1 control the development of distal portion. Furthermore, the formation of joints is crucial for the development of ventral limbs. Notch signaling related regulators, such as the ligand gene (Dl and Ser), the modifier gene (fng) and the downstream target genes (odd, sob, drm and bowl), regulate that process. Studies on genes involved in the development of the ventral limbs are essential for well understanding the mechanisms that produce the appendages and revealing how the diversity in limbs has been evolved.

Key words: Insect, development, appendages, ventral limbs, gene expression, gene regulation