Sex accessories morphology and functions during the seasonal testicular cycle of a subtropical wild avian species, the yellow-throated sparrow Petronia xanthocollis Burton

Annual changes in the male sex accessories (tubuli recti, rete testis, vasa efferentia, epididymis, vas deferens and seminal glomus) were studied duri ng the annual testicular cycle of the yellow-throated sparrow (Petronia xan thocollis Burton). All the segments of genital tract and the seminal glomus became enlarged during the progressive phase (January to March), were maxi mally enlarged during breeding (April), began to decrease during regression (May and June) and became maximally regressed during the nonbreeding phase (July to December). But the sialic acid level of the seminal glomus increa sed to maximum already during the progressive phase, remained high during b reeding and declined subsequently. The findings suggest that the male sex a ccessories functions vary distinctly with the annual testicular cycle presu mably due to alterations in the testicular androgen production in the yello w-throated sparrow.