Biotechnology - High Tech High
Regional Occupational Program
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Student Projects - Fertilization and Development
The sea urchin has continued as important material for both cell and developmental biologists, and together with the frog and mouse probably constitutes the best material for investigation of many problems of development of deuterostomes, including cell-cell interactions. The material is easily handled for biochemical and molecular work, yet is amenable to micromanipulation and microsurgery.

The ripe sea urchin egg has completed meiosis, its polar bodies have disappeared , and it is shed in a completely mature state. Upon insemination, the egg undergoes a dramatic cortical reaction, marked by exocytosis of cortical granules and consequent formation of the fertilization envelope.

VIDEOS: 

COLLECTION Win Med Quick Time
SPAWNING Win Med Quick Time
FERTILIZATION Win Med Quick Time

In Strongylocentrotus purpuratus (purple sea urchin) pronuclear fusion will take place at about 25 minutes post fertilization at 15 oC. The first cleavage will occur at about 100 minutes. The succeeding divisions will then occur every 60 minutes.

 (above) Stages shown in animation: -egg
-morulla
-blastula
-gastrula
-prism
-pluteus (1st feeding stage)
-8 arm pluteus (w/ rudiment)
-juvenile

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