Light and fine structural studies of natural and artificially induced egg growth of penaeid shrimp.

Abstract

Egg differentiation in penaeids induced to undergo gonad maturation by eyestalk ablation has been examined with light and electron microscopes. Controls consisted of both wild brown and white shrimp (Penaeus aztecus and P. setiferus) caught south of Freeport, Texas and off Galveston, Texas, in various stages of ovarian maturation. These animals were sacrificed and ovarian tissues were excised and fixed in a cold (4 C) aldehyde mixture, post- fixed in osmic acid, dehydrated in acetone, and embedded in an epoxy resin. Experimental animals included laboratory-reared, wild immature, and wild mature animals which had resorbed ovarian tissues. These animals were ablated with hot surgical clamps and sacrificed at various time intervals. Tissues were prepared as described for the controls. The development of ova from experimental animals were compared to control animals. In the stages early oocyte, cisternal phase, platelet phase, cortical rod phase, and mature oocyte, the experimental oocytes appeared the same as the control tissues. Though further studies (e.g., biochemical and zygote development) are needed, these preliminary fine structural studies are encouraging. While ablation, a mechanical process, may not be the technique of choice for maturing shrimp, it does indicate that manipulation of the endocrine system will be successful.