3,320
edits
Changes
Blastocyst Embryonic Development - Anatomy & Physiology (view source)
Revision as of 14:59, 4 September 2008
, 14:59, 4 September 2008→Pre-Implantation Development
== Pre-Implantation Development ==
== Pre-Implantation Development ==
* The sperm enters the the oocyte forming the ootid.
* In the Ootid, male and female '''pronuclei''' along with the first and second '''polar bodies''' are present.
* In the Ootid, male and female '''pronuclei''' along with the first and second '''polar bodies''' are present.
* Fusion of the male and female pronuclei results in a single '''diploid nucleus''' ('''Syngamy''')
* Fusion of the male and female pronuclei results in a single '''diploid nucleus''' ('''Syngamy''')
* This causes the '''zona pellucida''' to form around the zygote. This is an imprenetrable layer that prevents polyspermy and so polyploidy.
* '''Zygote''' (diploid) undergoes mitotic divisions ('''cleavage''').
* '''Zygote''' (diploid) undergoes mitotic divisions ('''cleavage''').
* Cleavage gives rise to daughter cells called '''Blastomeres'''.
* Cleavage gives rise to daughter cells called '''Blastomeres'''.