A fine structural investigation of oogenesis in the brown shrimp Penaeus aztecus

The ovary of Pennons aztecus is located in the dorsal cephalothorax and consists of anterior, lateral, and posterior lobes. Follicular egg development is exhibited, with the follicular cell layer present until spawning. Vitellogenesis may be divided into early and late production of yolk materials. The swelling of short discontinuous elements of rough endoplasmic reticulum is responsible for the early (intracellular) aspect of yolk production. Micropinocytotic uptake of materials at the oolemma and the subsequent fusion of the micropinocytotic vesicles contribute to the late (extraoocytic) phase of yolk platelet production. The most striking morphological attribute of the mature oocyte is the presence of large cortical rods. These rods demonstrate a partial cortical reaction prior to spawning and a subsequent "explosive" ejection of their contents at spawning.