Giant nebenkern produced by colcemid treatment of the spermatocysts of the silkworm,Bombyx mori

Abstract

Summary.The silkworm spermatocysts isolated from testes were cultured for 24 h in a medium containing 1 gg of colcemid per ml, which is an inhibitor of tubulin association to microtubules. In the present experiment, the suppression of meiotic division I by this treatment resulted in the formation of a "giant nebenkern" in the primary spermatocyte. Normally, the nebenkern, an organelle in which all the cell's mitochondria aggregate, is formed in the spermatids of insects and changes into elongated mitochondrial derivatives. After washing with the culture medium without colcemid, the cell bearing the giant nebenkern grew to be a sperm with four flagella. When meiotic division II was blocked, the secondary spermatocytes with a nebenkern appeared and the further culture resulted in sperm with two flagella. These results suggest that the formation of a nebenkern is a necessary step toward the final stages of spermiogenesis.

Peristaltic squeezing of sperm bundles at the late stage of spermatogenesis in the silkworm,Bombyx mori

“…Since the culture of whole testes was not successful, spermatocysts or sperm bundles were isolated from the testes and cultured in the medium containing either colcemid (Sigma Chemical Co.) or cytochalasin D (Sigma Chemical Co.). Bombyx hemolymph was added to the culture medium for the prolonged culture of sperm bundles as a modification of the previously described method of Kawamura and Yamashiki (1999). The excised testes were passed through three changes of sterilized saline solution and spermatocysts and sperm bundles were isolated in the culture medium (10% fetal bovine serum in TC100 solution for insect cell culture; Sigma Chemical Co.).…”