An ultrastructure comparison of the plasmodium and sporangium of an undescribed species of Labyrinthomyxa parasitic in Crassostrea virginica (Gmelin).

A comparison is made between the ultrastructure of the plasmodial and sporangial stages of Labyrinthomyxa sp. cultured on Watson's Blood Serum Medium. Cristae mitochondriales in the sporangia are of the microtubular type, while they are of the lamellar type in the plasmodia. Dictyosomes are reported for the first time in each of these stages and a secretory activity is indicated in the sporangium. The biochemical nature of presumptive lipid appears to differ in the two stages. An ultrastructure comparison is made with a member of the Saprolegniales (Oomycetes) suggesting a possible reassessment of certain members of the Thraustochytriaceae.