Early Drosophila Embryogenesis
Haven't seen a tag for this so I assume it hasn't been posted before. ^^; I hail from a lab that does work with Drosophila melanogaster (also known as the common fruit fly) and it's fascinating to watch their embryos develop before my eyes.
Unlike most animals, fruit flies embryos undergo superficial meroblastic (incomplete) cleavage and become syncytic (multi-nucleated). This means that instead of having the fertilized egg cleaving itself into multiple, smaller cells, the embryo simply becomes a massive cell with many nuclei. Regulated by signals in the shared cytoplasm that surrounds them, the nuclei all divide and replicate at the same time. This continues for 13 cycle so the end result is a massive embryo with thousands upon thousands of nuclei. (After 13 cycles, cellularization begins and the nuclei are eventually separated into their own cells.)
Like most insects, fruit flies have fast life cycles and use meroblastic cleavage to save time on development. 12 hours after being fertilized, the eggs already contain an astounding 50,000 cells. In comparison, frog eggs have about 37,000 cells after 43 hours. Drosophila eggs usually only take a day to hatch at room temperature but can hatch a few hours earlier if placed in a warmer area.
The coolest thing about all this is that each nuclear division is only separated by a few minutes so you can literally see the embryo develop before your eyes. It's strangely soothing (and addicting) to watch the embryo develop, as you can see from these videos.
Video #1:
Video #2: (a real-time close-up)
Video #3: (I can't figure out a way to embed this one, so you'll just have to click the link)
http://cellimages.ascb.org/cdm4/item_viewer.php?CISOROOT=/p4041coll12&CISOPTR=254&CISOBOX=1&REC=3
Unlike most animals, fruit flies embryos undergo superficial meroblastic (incomplete) cleavage and become syncytic (multi-nucleated). This means that instead of having the fertilized egg cleaving itself into multiple, smaller cells, the embryo simply becomes a massive cell with many nuclei. Regulated by signals in the shared cytoplasm that surrounds them, the nuclei all divide and replicate at the same time. This continues for 13 cycle so the end result is a massive embryo with thousands upon thousands of nuclei. (After 13 cycles, cellularization begins and the nuclei are eventually separated into their own cells.)
Like most insects, fruit flies have fast life cycles and use meroblastic cleavage to save time on development. 12 hours after being fertilized, the eggs already contain an astounding 50,000 cells. In comparison, frog eggs have about 37,000 cells after 43 hours. Drosophila eggs usually only take a day to hatch at room temperature but can hatch a few hours earlier if placed in a warmer area.
The coolest thing about all this is that each nuclear division is only separated by a few minutes so you can literally see the embryo develop before your eyes. It's strangely soothing (and addicting) to watch the embryo develop, as you can see from these videos.
Video #1:
Click to viewVideo #2: (a real-time close-up)
Video #3: (I can't figure out a way to embed this one, so you'll just have to click the link)
http://cellimages.ascb.org/cdm4/item_viewer.php?CISOROOT=/p4041coll12&CISOPTR=254&CISOBOX=1&REC=3