Tissue migration, growth, and morphogenesis of Filaroides martis (Nematoda: Metastrongyloidea) in mink (Mustela vison)

Abstract

Filaroides martis (Werner 1782) Dougherty, 1943 undergoes its third molt in the gastric mucosa of mink (Mustela vison Schreber) 3–4 days after infection. The fourth molt occurs in the submucosa about 5 days after infection. Worms start to leave the stomach as subadults on day 9 and migrate along the adventitia or adipose tissue on the coeliac artery, and the dorsal aorta, reaching the lung region as early as 15 days after infection. By day 35 most worms have reached the bronchi or trachea.Filaroides martis starts to grow extensively in gastric subserosal adipose tissue 9 days after infection. During migration worms grow in connective tissues in various locations along the migratory route and they are various sizes when they reach the lungs. Worms increase more than 100 times in length in 25 days.The morphogenesis of F. martis is described. Sexes are distinguishable about 5 days after infection. On day 9 the reproductive tract of females is branched and a vagina vera is present. At the same time the reproductive tract of males has joined the rectum and by day 15 well-developed spicules and gubernacula are present.