title: Elongated microvilli support the sea urchin embryo concentrically within the perivitelline space until hatching.
abstract: The early sea urchin embryo is supported in a concentric position within the perivitelline space by elongated microvilli which are attached to the fertilization envelope by extracellular matrix fibers. This "attachment complex," of microvillus tip: extracellular matrix fibers: fertilization envelope, was revealed by two methods: the use of pronase or calcium-free sea water to dissolve the extracellular matrix fibers, thus causing the eggs to lose their concentric location, and the visualization of the "attachment complex" using video-enhanced differential interference contrast microscopy and transmission electron microscope images. The presence of the "attachment complex" helps in understanding two types of early developmental events: (1) the apparently continual change in microvillus length during cleavage stages which retains the embryos in their concentric position and (2) the hatching process.
authors.affiliation: Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA.|Marine Biological Laboratory, 02543, Woods Hole, MA, USA.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Spiegel
authors.affiliation: Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA.|Marine Biological Laboratory, 02543, Woods Hole, MA, USA.
authors.forename: Louisa
authors.initials: L
authors.lastname: Howard
authors.affiliation: Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA.|Marine Biological Laboratory, 02543, Woods Hole, MA, USA.
authors.forename: Melvin
authors.initials: M
authors.lastname: Spiegel
keywords: Elastic support; Elongated microvilli; Extracellular matrix; Hatching process; Sea urchin embryo