Pictures in the Banner
Embryonic Killifish Epithelial Cells
These two panels are of embryonic killifish epithelial cells, stained
with a fluorescent lipid. This bright orange molecule is incorporated
into the plasma membrane of the cells. In killifish (but not most other
fish) the epithelial cells have special membrane properties such that
you can actually watch membrane turnover using these fluorescent markers.
With time, the fluorescent lipid is cleared from the membrane (internalized
by a process called endocytosis)--first at the "corners" where
These four panels are of sea urchin embryos. The first shows a newly fertilized egg. The large "dot" you can see near the top of the spherical zygote is the egg nucleus, and the smaller dot near 5 o'clock is the nucleus delivered by the successful sperm. The embryo is surrounded by a clear fertilization envelope, which prevents any other sperm from fusing with the egg. In the second panel, you are looking at a sixteen-cell-stage urchin embryo. At this stage, the embryo is made of four small cells (foreground), four larger cells, and 8 middle-sized cells (out of focus in the background). The third panel shows a gastrula-stage embryo, and the large tube in the middle is the archenteron, or embryonic gut. In the fourth panel, you can see a mature, swimming, feeding urchin larva called a pluteus. The bright lines you can see are the larval skeleton, made of calcium carbonate. To see a video of such an embryo, go to the Biology 305 class video page.
Tiny Rear Fin of a Larval Squid
This is the tiny rear fin of a larval squid. The embryo was soaked in
a fluorescent lipid, which was taken up by the peripheral nerve cells.
You can see the brightly-staining orange nerve cell bodies along the
periphery of the fin, and the long filamentous axonal processes extending