EGG,   SPERM, 

BLASTOCYST

NOTE - MODEL IS NOT TO SCALE

F          beginning of first mitotic division             (cleavage) of zygote

 

 

A         primary follicle containing oocyte

G         2-cell stage

            (light purple spot; 

 

            dark purple spots are nuclei)

H         8-cell stage

I           primary follicle

 

II          antrum (fluid-filled cavity) of growing     primary follicle

I           morula

III        mature Graafian follicle

 

 

J             early blastocyst (4 days)

B  ovulated oocyte (arrow =     polar body)

 

 

K         late blastocyst (7 days, at implantation)

C         sperm

 

 

 

27        head with acrosome

 

28        body with midpiece

 

29        flagellum (tail)

 

 

 

D         sperm penetration (arrow = meiotic fig.)

 

 

 

E           pronuclei fusing (fertilization;  note

 

            second polar body)