(anatomy) Any of various glands that secrete hormones directly into the blood or lymph and not through a duct.

Produced, originating or growing from within. / Of a natural process: caused by factors within the body.

in danger, at risk, said of something where there is a strong possibility something bad will happen to it (for example, a species in danger of going extinct)

simple past tense and past participle of endanger

Long-lasting without significant alteration; continuing through time in the same relative state.

present participle of endure

endurance

An instrument used to examine a bodily orifice or canal, or a hollow organ.

upright, or standing on end / with the end towards the front or towards the observer / towards the ends

On-end; upright; pertaining or relating to the end.