How does the endoparasite Pinworms survive while in the human intestine?
The life cycle begins with eggs being ingested. The eggs hatch in the duodenum (i.e., first part of the small intestine). The emerging pinworm larvae grow rapidly to a size of 140 to 150 micrometers in size, and migrate through the small intestine towards the colon. During this migration they moult twice and become adults. Females survive for 5 to 13 weeks, and males about 7 weeks. The male and female pinworms mate in the ileum (i.e., last part of the small intestine), then the male pinworms usually die. Male and female worms reproduce sexually, but their union produces only female larvae. Male larvae are a product of parthenogenisis – the development of an unfertilised egg. The gravid female pinworms settle in the ileum, caecum (i.e., beginning of the large intestine), appendix and ascending colon, WHERE THEY ATTACH THEMSELVES TO THE MUCOSA AND INGEST COLONIC CONTENTS. Almost the entire body of a gravid female becomes filled with eggs. The estimations of the number of eggs in a gravid
