Adult strongyle with large buccal capsule and leaf crown
This image shows anatomic features typical of the horse small strongyles. The buccal capsules of horse small strongyles are usually wider than deep. They also have leaf crowns. A leaf crown is the fimbriated structure surrounding the mouth: leaf crowns are present on all members of the superfamily Strongyloidea except hookworms.
Anterior end of Ostertagia ostertagi
Typical trichostrongyle showing the absence of large buccal capsule. The cervical papillae the are present on this worm are present on adult males and females of the genera Ostertagia, Haemonchus, Marshallagia and Hyostrongylus.
Image shows cuticular striations within the cuticle of adult worms. Although sometimes difficult to see they are considered to be an identifying characteristic of this genus.
Adult Trichuris vulpes
The long whip-like structure (neck) is called a stichosome which is comprised of a single row of donut-shaped cells called stichocytes. Capillaria spp. and Trichinella spp. also possess stichosomes but the worms are much smaller. Only the whipworm has a neck as long as is seen in this specimen.
Infective third stage larvae
Two types of filariform infective L3 larvae are shown here. The larva with the long esophagus is Strongyloides canis; unensheathed larvae with the long esophagus (1/3 to 1/2 the body length) is diagnostic for the genus Strongyloides. The ensheathed filariform larva is Ancylostoma caninum and the short esophagus and sheath are typical of both strongyles or trichostrongyles.
Filarial microfilariae in a blood smear
The multinucleated syncitial morphology is the distinguishing characteristic of this type of larval stage. The presence or absence of a sheath, general size and position of nuclei are used to identify the genus to which they belong when found in blood.
Enface view of an adult ascarid
This image clearly shows the three large lips that surround the mouths of all ascarid species. The lips are specific to ascarids as a group and are usually obvious when viewing a gross specimen with low magnification.
Adult female pinworm (Oxyuroidea)
This image shows an adult female pinworm demonstrating the large double-bulbed esophagus charateristic of all species with the group. Females posses a sharply pointed tail from which the common name is derived. Male pinwoms are smaller than females and do not have a pointed tail. Male pinworms may (depending on species) have cephalic vesicles,