REPRODUCTION IN BATHYPLOTES-NATANS (HOLOTHURIOIDEA, SYNALLACTIDAE) FROM BATHYAL DEPTHS IN THE NORTHEAST AND WESTERN ATLANTIC

The gross morphology, histology, ultrastructure and periodicity of gon ad development of the bathyal aspidochirote holothurian Bathyplotes na tans is described and compared with the 'tubule recruitment model' pro posed for aspidochirote holothurians. As B. natans grows, additional g onad tubules develop at the anterior end of the gonad basis. Oocyte de velopment in these tubules is non-seasonal and the population of oocyt es consists of both pre-vitellogenic and vitellogenic oocytes as well as some large oocytes undergoing phagocytic breakdown. Vitellogenesis is similar to that described previously for holothurians, although the follicular inner epithelium cells surrounding the developing oocytes are different from those previously reported. In males the unique acro somal complex consists of three depressions with the acrosome lying in the central depression. The tubule recruitment model of Smiley does n ot apply to B. natans. We do not feel this model has widespread applic ability in the Aspidochirotida or the Holothurioidea in general.