THE DEVELOPMENT OF THE OVOTESTIS AND COPULATORY ORGANS IN A POPULATION OF PROTANDRIC SHRIMP<i>PANDALUS PLATYCEROS</i>BRANDT FROM LOPEZ SOUND, WASHINGTON

Abstract

1. The relationship between age and carapace length to the state of gonadal development in Pandalus platyceros Brandt is presented. The development of the ovotestis is shown to be a function of size (carapace length) and not age. 2. The copulatory appendages of the pleopods appear to pass through seven or eight stages from the immature form to the adult female stage. 3. The development of the ovotestis is described with special reference to the origin of gonial cells. It appears that oocytes and spermatocytes derived from two distinct germinal areas of the gonadal epithelium. The lateral germinal ridges give rise to spermatogonia and acinar cells; the medial germinal ridge oogonia and follicle cells. 4. The flattened triangular spermatozoa are derived from the tetrahedrally arranged tetrads of spermatids. 5. Transformation to the female stage generally is initiated only after the males have produced spermatozoa. The lateral germinal ridges appear to have lost their ability to form spermatogonia since they have differentiated into prostatic like mucous producing cells. 6. In the transforming stage, the degenerating cortical testicular tissue forms the thickened outer sheath of the ovary. Four months after spermatozoa formation, the sperm ducts are filled with sperm, the copulatory organs are still masculine; but the gonad lacks testicular tissue and becomes a true ovary.