Baylisascaris procyonis, the intestinal ascarid parasite of raccons (Procy-
on lotor), has been implicated as an etiologic agent of human visceral
larva migrans (VLM), central nervous system (CNS) disease, and ocular
larva migrans (OLM)_ We have studied the early embryonic development
as well as the second larval stage (L2) of B-procyonis in order to
identify morphological features which will allow differentiation oi
this parasite lrorn other nematode larvae.
The eggs of B.pmcyonis measured 72-81 by 60-66 microns and develo-
ped to infective stage in ll to 14 days at 25“C. L, prepared by
artilicial hatching in vitro measured lit-18 microns in diameter by
275-290 microns in length. Eprocyonis L, had a characteristic pronou-
nced oral protuberance, lateral alae, a funnel-shaped buccal vestibule,
and the tail terminated in a button- shaped knob. Microtopography
of B.procyonis second stage larvae was studied in detail by scann-
ing electron microscopy. The anterior end was tapered to form a
longitudinally striated cephalic cone. The tip of the cephalic cone
was protruded, truncated, and consisted of three dorsal and two
subventral lip-like oesophageal protrustions. The dorsal lip-like oecoph-
ageal protrusion was separated from the fused subventrals. A pair
of amphidial pores were located laterally and slightly dorsal to the
subventral oesophageal protrusions. A cuticular cap from the first
moult sheath sometimes appeared on the ocsophageal protrusion.
Prominent lateral alae extended anteriorly from the base of the cepha-
lic cone to the tail posteriorly. The excretory pore was surrounded
by a prominent rim, and an oval cuticular bleb or thickening was
iound anterior to the anal orifice.