Mature ovaries or testes can be identified only in sections because of the different structure of spermatozoa and ova they contain. The testes present a streaky appearance due to presence of spermatozoa. The mature sperm of branchiostoma one of the smallest among chordates in length. It consist of the nucleated head with acrosome a middle piece and a long tail. The ovary contain ova which are large and some what rounded cells each 0.i mm in diameter and having a large nucleus. They are microlecithal or poor in yolk content. Gonoducts are abesenr. Mature gametes are discharged into the atrium by rupture or dehiscence of gonadial wall along certain waeker spots called cicatrices which after wards close. The gametes so liberated escape through atriopore with the outgoing water current.
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