part of develops from adult gonad male reproductive system testis FBbt:00004928 Tube of the male reproductive system connected to the seminal vesicle at the basal end. It is a tube 1.9mm long and 90-100 micrometers in diameter, with the basal half helically coiled and the distal half forming a freely extended arc. The coiled portion is spirally wound twice around a center occupied by the testicular duct and the distal portion of the seminal vesicle. The wall of the testis consists of two very thin layers containing widely spaced nuclei: an inner sheath and an outer sheath composed of small flattened polygonal cells that contain yellow pigment granules. The development of germline cells takes place in the testis. UBERON:0000473 fly_anatomy.ontology male-specific anatomical entity larval testis