PMC

Immunohistochemistry and immunocytochemistry of sea urchin tissues and cells using an antibody to Vasa. Esophagus, radial nerve, coelomocytes, tube foot, and spine from Lytechinus variegatus stained with DAPI or reacted with anti‐Vasa antibody visualized with DyLight^™ 488 secondary antibody. Negative control panels are tissue sections treated with only the secondary antibody. Scale bar is 100 μm.

Relative gene expression for pcna, tert, seawi, and vasa in tube feet from Lytechinus variegatus (Lv) and Strongylocentrotus purpuratus (Sp). The white bars represent small/young animals and the black bars represent large/old animals. Age estimates and number of animals in each group are shown in Table . Data are presented as means and standard errors.

Relative gene expression for pcna, tert, seawi, and vasa in tissues of Lytechinus variegatus (Lv), Strongylocentrotus purpuratus (Sp), and Mesocentrotus franciscanus (Mf). The white bars represent small/young animals and the black bars represent large/old animals and the tissues investigated are: Aristotle's lantern muscle (Muscle), Esophagus, Radial Nerve, and Coelomocytes. Age estimates and number of animals in each group are shown in Table . Data are presented as means and standard errors, and stars (*) indicate a significant difference between age groups (P < 0.05).

Regeneration of tube feet and spines with respect to age in Lytechinus variegatus (A and B) and Strongylocentrotus purpuratus (C and D). Regrowth of tube feet and spines was measured at 8, 15, 22, 29, and 36 days postamputation and expressed as a percentage of full‐length, nonamputated appendages. The white bars represent small/young animals and the black bars represent large/old animals. Age estimates and number of animals in each group are shown in Table . The data are presented as means and standard errors, and stars (*) indicate a significant difference between age groups (P < 0.05).

Cell proliferation and apoptosis in sea urchin tissues. Percent of cells undergoing cell proliferation (BrdU incorporation) and apoptosis (Apo ssDNA and TUNEL) in tissues of Lytechinus variegatus (A–C), Strongylocentrotus purpuratus (D–F), and Mesocentrotus franciscanus (G–I). The white bars represent small/young animals and the black bars represent large/old animals and the tissues investigated are: Aristotle's lantern muscle (ALM), esophagus (ES), radial nerve (RN), and coelomocytes (Coel). Age estimates and number of animals in each group are shown in Table . The data are presented as means and standard errors, and stars (*) indicate a significant difference between age groups (P < 0.05).

Sea urchin anatomy and tissue regeneration. (A) Cross sectional view of Lytechinus variegatus showing tissues used in this study: spine, gonad, muscle from Aristotle's lantern jaw structure, esophagus, radial nerve along the inside wall of the test (shell) surrounded by the ampulla, part of the water vascular system which is continuous with the tube feet that protrude through the test. Coelomocytes freely circulate in the coelomic fluid that fills the body cavity. B through D show the spine and tube feet regeneration assay using Strongylocentrotus purpuratus. (B) Aboral view 1 day postamputation showing tube feet and spines removed from along one of the ambulacral segments of the test from the oral to aboral surface. (C) Lateral view of the amputated region, 8 days postamputation. (D) Lateral view of the amputated region from the same animal, 36 days postamputation.