GAMETOGENESIS
Pre-embryonic period: First 2 weeks.
Embryonic Period: 3 to 8 weeks.
Fetal Period: 9 weeks till birth.
Primordial germ cells
It forms the germ cells.
It is produced by epiblast during the second week.
Male germ cell: Spermatozoa.
Female germ cell: Ovum.
Primordial germ cells migrate to yolk sac by 4th week.
They reach gonads by 5th week.
Male gonads: Testis.
Female gonads: Ovary.
Primordial germ cells are pluripotent (the ability to form all germ layers).
Totipotent cells: Ability to form an entire embryo and extraembryonic tissue.
Up to 8 cell stage, each cell is totipotent
Pre-embryonic period: First 2 weeks.
Embryonic Period: 3 to 8 weeks.
Fetal Period: 9 weeks till birth.
Primordial germ cells
It forms the germ cells.
It is produced by epiblast during the second week.
Male germ cell: Spermatozoa.
Female germ cell: Ovum.
Primordial germ cells migrate to yolk sac by 4th week.
They reach gonads by 5th week.
Male gonads: Testis.
Female gonads: Ovary.
Primordial germ cells are pluripotent (the ability to form all germ layers).
Totipotent cells: Ability to form an entire embryo and extraembryonic tissue.
Up to 8 cell stage, each cell is totipotent
