Mature proglottid of Diphyllobothrium

(Redrawn after Brown and Belding 1964)

There is a central ovary and a uterus and genital pore that occur on the midline of the proglottid. Vitelline follicles occur over the entire surfce of the proglottid, in the superficial layer of tissue. Beneath the vitellaria, but also throughout the proglottid, are a large number of testes.