2. Growth (spermatogonia to primary spermatocytes)
3. Maturation (meiotic division of primary spermatocyte)
4. Differentiation (spermatid to spermatozoon)
Oogenesis
It occurs in the ovaries and fallopian tubes
The follicles of the ovary exert hormonal influence
It starts during the pregnancy of the mother
Oogenesis
1. Proliferation (oogonium mitotic division)
2. Growth (oogonium to primary oocyte)
3. Maturation (meiotic division of primary oocyte)
4. Differentiation (ootid to ovum)
The polar body is a small meiotic product of the unequal division in oogenesis in females. It allows to concentrate the cytoplasmic contents into one ovum.
Human fertilization
Fusion of the gametes or sex cells from male and female parents
Sperm cell must pass through the granulosa and jelly coat layers
With slow-block and fast-block mechanisms against polyspermy
Produces the zygote with normal or restored chromosome number
Placenta
Structure during gestation that supplies the developing fetus with oxygen and nutrients from the mother, and removes the wastes accumulated by the fetus