Diplopodia is a congenital anomaly in tetrapods that involves duplication of elements of the foot on the hind limb. It comes from the Greek roots diplo = "double" and pod = "foot". Diplopodia is often found in conjunction with other structural abnormalities and can be lethal. It is more extreme than polydactyly, the presence of extra digits. Description
The affected leg usually has one foot that is in an approximately normal position. The extra foot is composed of at least some metatarsal or tarsal bones and extra digits, though it is usually not complete. The feet can be joined together, so that the limb appears to have one large foot, or the extra foot can be joined to the limb separately, usually above the level of the other foot. Diplopodia affects one or both of the hind limbs. Causes
Recessive alleles of some genes involved in embryonic limb patterning produce bilateral diplopodia, and diplopodia can be experimentally induced in early embryos. Many instances of diplopodia in humans have no apparent cause.People have been able to produce diplopod limbs by increasing sonic hedgehog (shh) signaling in the limb buds of embryos. The zone of polarizing activity (ZPA) in the proximal posterior mesoderm of a tetrapod limb bud is responsible for maintaining the anterior-posterior axis of the growing limb. The ZPA secretes shh protein, which induces formation of the distal segment of the limb, or autopod, with its posterior side facing the ZPA.
Merrem may refer to:

Meropenem, an antibiotic initially marketed under the trade name Merrem
Blasius Merrem (1761–1824), German naturalist, zoologist, ornithologist, mathematician, and herpetologist