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Reinvestigates the origins of tentacles in Mnemiopsis leidyi. Utilization of the intracellular injection of DiI (3,9); Results obtained; Complexity of tentacle formation.

Presents an experimental procedure aimed to determine the exact origins of the mesoderm in nemerteans using Cerebratulus lacteus. Findings on mesoderm in C. lacteus originating as ectomesoderm from 3a and 3b micromeres, and endomesoderm from 4d micromere; Support of reported data to the high conservation of the spiralian development program.

Examines the embryological origin of the new structures formed during the larval period of ctenophore. Use of cell lineage techniques; Determination of lineage's capacity to produce ctene plates during embryogenesis and post-generation; Difference in comb plates' appearance during larval and embryogenesis period.

Reports on the establishment of the anal axis in the ctenophore Mnemiopsis leidyi. Existence of definitive muscles in the mesoglea and in association with both epithelial layers; Major body axis as the intersection of two orthogonally situated planes of mirror symmetry; Definition of four quadrants; Reflection of biradial symmetry in embryonic development.

Focuses on the embryos of the acoel turbellarian Platyhelminthes modified from spiral cleavage wherein only two macromeres are formed before pairs of micromeres arise at the onset of the four-cell stage. Experimentation with N. fusca reveals different acoel development with that of quartet-cleaving species; Ancestral attribution of duet cleavage pattern.

Reports on the alteration of cell lineages in the nemertean Cerebratulus lacteus. Shifting the orientation of the spindle to alter the plane of the first cleavage; Compression of fertilized eggs; Forcing the cleavage spindle to align parallel to the plane of compression; Occurrence of cytokinesis perpendicular to the cleavage spindle.

Reports on the axial specification in spiralian clade. Sharing common features of embryonic development such as sterotypic pattern of cell divisions known as spiral cleavage; Occurrence of first cleavage oblique to the future plane of bilateral symmetry; Generation of two blastomeres; Examination of first two cleavage planes of Hoploplana inquilina.

Tests whether embryonic cells of Cerebratulus lacteus can regulate or generate missing structures that they would not normally produce in the intact embryo. Isolation of blastomeres from four-celled embryos; Assay for development of larval muscle fibers; Ability to form dorsal blastomeres when separated from ventral cells.