Skin penetration of infective hookworm larvae. I. The path of migration of infective larvae of Ancylostoma braziliense in canine skin.

Migratory behaviour of Ancylostoma braziliense was studied in relation to the structure of the skin in dogs after primary infections. Data were obtained studying serial sections of lateral skin areas 6 mm in diameter, which had been exposed to larvae. The sections were stained either with Harris' haematoxylin and eosin or with P.A.S. or as outlined by Crossmon. Most of the larvae managed to penetrate the skin within 1/2 hr after the application. Hairs did not seem to constitute sites of entry. The larvae moved into the horny layer where edges of keratinized cells provide uneven spots. They migrated approximately parallel to the surface from the horny layer into the living epidermis and continued into an external root sheath of a hair follicle. They could only leave this site via sebaceous glands for the dermis or via apocrine sweat glands for the hypodermis. Tunnels from the epidermis into the dermis, however, suggested that a direct trans-epidermal migration had occurred. The vessels invaded by larvae were hypodermal lymphatic vessels. The first ones were found in these structures 1/2 h after the onset of the exposure.