Which of the following statements are incorrect for spermatogenesis?

(i) In testis, the immature male germ ceils spermatogonia produce sperms by spermatogenesis that begins at puberty.

(ii) Some of the spermatogonia called primary spermatocytes periodically undergo meiosis.

(iii) The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis.

(iv) Sperm released from the seminiferous tubules by the process called spermiation.

(v) Spermatogenesis starts at the age of puberty due to significant increase in the secretion of gonadotropin releasing hormone (GnRH).

(vi) Androgens stimulate the process of spermatogenesis.

(vii) FSH acts on the Sertoli cells and stimulates secrtion of some factors which help in the process of spermiogenesis.