noun, plural: seminiferous tubules
Seminiferous tubules are coiled (for the most part) tubules found within the testes. They are the site where spermatozoa (male gametes) are produced. The epithelial lining of the seminiferous tubule consists of Sertoli cells, which are sustentacular columnar cells, and spermatogenic cells that give rise to sperm cells. The Sertoli cells are essential for the nourishment and the development of the sperm cells. They secrete testis-determining factor that increases the concentration of testosterone in seminiferous tubules.
There are two types of seminiferous tubules: (1) the convoluted seminiferous tubules and (2) the straight seminiferous tubules. The convoluted seminiferous tubules are those twisted curved tubules in each lobule of the testis. They are where spermatogenesis occurs. The straight seminiferous tubules are the continuation of the tubulus seminifer contortus which becomes straight just before entering the mediastinum to form the rete testis.