We screened the gene that encodes tetratricopeptide repeat domain 29 (Ttc29) in the maturing rat testis. Gene expression was determined by Northern blotting of 7-week-old rat testes, and a strong signal was detected close to the 18S rRNA band in addition to two weak high-molecular-weight signals. In situ hybridization revealed that Ttc29 was expressed primarily in the spermatocytes. We evaluated the effect of gonadotropin on Ttc29 expression using hypophysectomized rats. The pituitary was removed from 3-week-old rats, gonadotropin was injected at 5 weeks, and Ttc29 expression was determined at 7 weeks. Although testicular development and hyperplasia of interstitial cells were observed following chorionic gonadotropin treatment after hypophysectomy, Ttc29 expression was upregulated by treatment with follicle-stimulating hormone. Ttc29 encodes axonemal dynein, a component of sperm flagella. Taken together, these data indicate that axonemal dynein expression starts in the spermatocytes and is regulated by follicle-stimulating hormone.