Question

differentiated between pretesticular and testicular nephridia in leech

Answer 1

Pre-testicular nephridium: Structurally these nephridia resemble the testicular nephridia except that they lack ciliated organs. This is because the testis sacs in those segments are not formed. The initial lobes end loosely within the connective tissue on each side of the ventral nerve cord.

Answer 2

Leech Excretory system consists of 17 pairs of small coiled tubes called the nephridia which is arranged segmentally. Nephridia are of two types i ) testicular ii) pre-testicular

i) Testicular nephridia- Posterior 11 pairs of nephridia lying one pair in each segment from 12 to 22nd, are termed testicular nephridia. They are called testicular nephridia, because they contain pair of testis sacs in each of these segments.

ii) pretesticular Nephridia- There are no testis sacs, peri-nephrostomial ampullae and ciliated organs in their segments so called this.