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* In the Ootid, male and female pronuclei along with the first and second polar bodies are present.
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* In the Ootid, male and female '''pronuclei''' along with the first and second '''polar bodies''' are present.
* Fusion of male and female pronuclei to form a single diploid nucleus ('''Syngamy''')
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* Fusion of male and female pronuclei to form a single '''diploid nucleus''' ('''Syngamy''')
* Zygote (diploid) undergoes mitotic divisions ('''cleavage''').
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* '''Zygote''' (diploid) undergoes mitotic divisions ('''cleavage''').
 
* Cleavage gives rise to daughter cells called '''Blastomeres'''.
 
* Cleavage gives rise to daughter cells called '''Blastomeres'''.
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* Cleavage divisions continue and the 4-celled Embryo gives rise to an 8-celled Embryo.
 
* Cleavage divisions continue and the 4-celled Embryo gives rise to an 8-celled Embryo.
 
* After the 8-celled stage, a ball of cells is formed.  This stage is referred to as a '''Morula'''.
 
* After the 8-celled stage, a ball of cells is formed.  This stage is referred to as a '''Morula'''.
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* '''Tight junctions''' form between outer cells of the Morula.
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* '''Gap junctions''' form between inner cells of the Morula.
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* Thus, two groups of cells are created within the Morula.
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* Outer cells pump Sodium into the intracellular spaces and water follows osmotically.
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* Fluid begins to accumulate within the Morula.
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* Cells  of the Morula continue to divide and a '''Blastocyst''' develops, consisting of:
* Cells  of the Morula continue to devide and a '''Blastocyst''' develops, consisting of:
   
** '''Inner Cell Mass''' (ICM)
 
** '''Inner Cell Mass''' (ICM)
 
** '''Blastocoele''' cavity
 
** '''Blastocoele''' cavity
 
** Single layer of '''Trophoblast''' cells
 
** Single layer of '''Trophoblast''' cells
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* As fluid accumulates, the outer cells become flattened and a cavity known as the Blastocoele is formed.
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* Gap junctions connecting the inner cells of the Morula enable them to polarise as a group.
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* As a result, two separate cellular components emerge - the Inner Cell Mass and the Trophoblasts.
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* Blastocyst ''''hatches'''' from the '''Zona Pellucida'''.
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* Blastocyst continues mitosis.
* Blastocyst free-floating within the Uterus.
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* Fluid accumulates to fill the Blastocoele and pressure within the embryo increases.
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* Concurrent with growth and fluid accumulation is the production of '''proteolytic enzymes''' by '''Trophoblastic''' cells.
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* Enzymes weaken the '''Zona Pellucida'''.
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* Blastocyst begins to contract and relax causing intermittent pressure pulses on the Zona Pellucida.
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* Zona Pellucida ruptures with the development of a small fissure just large enough for the Blastocyst to squeeze out.
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* Blastocyst ''''hatches'''' from the Zona Pellucida.
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** '''Rodent,Dog,Cat,Primate''': 8 days after fertilization
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** '''Ungulates''': 12 days after fertilization.
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* Blastocyst free-floating within the Uterus, totally dependent on the Uterine environment for survival.
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