Q.What is exogenous phase in the lifecycle of Ascaris ?

Exogenous development in Ascaris refers to the stage of the life cycle spent outside the human body, in the external environment.

After a female Ascaris in the human intestine lays fertilised eggs, these are passed out with the faeces; in the soil, under suitable warmth, moisture and oxygen, the egg develops internally — the first-stage larva forms and moults (via the rhabditiform larva) to reach the infective second-stage larva within the egg shell — entirely outside a host. This soil-based, extracorporeal development is called the exogenous phase, distinguishing it from the endogenous phase, which occurs once the infective e …