The etiology of arthrogryposis (multiple congenital contracture).

In laboratory animals, prenatal contractures have been induced by viruses, neuromuscular blocking agents, toxins, insecticides, hyperthermia, and limb immobilization. In agricultural animals, prenatal contractures are related to pregnant animals foraging on plants containing toxic alkaloids. Epizootics of prenatal contractures in cattle have been related to Akabane viral infections, which can now be prevented by vaccination.

Concepts of multiple congenital contractures (arthrogryposis) in man and animals.

This is a concept of multiple congenital contractures, based upon clinical experience with the malformation and available literature, leading to a conception of the multiple categories of etiology, which cause neuropathic or myopathic muscle weakness or limb immobilization. The muscle weakness and imbalance of muscle power around the joints elicits a physiological compensatory collagenic response, which replaces atrophied muscle fibers with connective tissue and thickens the joint capsule sufficiently to result in prenatal fixation of limb segments at the joint.

Urogenital anomalies in fetal rats produced by the anticancer agent 4(5)-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide.

Pregnant Wistar rats injected intraperitoneally on gestational day 12 with single doses (100-1,000 mg/kg) or 600 mg/kg of 4(5)-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide (dic) were autopsied on day 21 (100-1,000 mg/kg) or at 24-hour intervals on days 13-20 (600 mg/kg). Controls received CMC on the same schedule. All fetuses were weighed and examined for urogenital system (UGS) malformations.