蛔虫
"Ascaris lumbricoides" is characterized by its great size. Males are in diameter and long. The male's posterior end is curved ventrally and has a bluntly pointed tail. Females are wide and long. The vulva is located in the anterior end and accounts for about one-third of its body length. Uteri may contain up to 27 million eggs at a time, with 200,000 being laid per day. Fertilized eggs are oval to round in shape and are long and wide with a thick outer shell. Unfertilized eggs measure long and wide.