2.  Cells and gametes (reproductive cells)
 DNA and chromosomes
 Cell cycle
 Cell division and types – Mitosis and
Meiosis
 Spermatogenesis and Oogenesis
 Fertilization and embryo development

3. Our cells contain chromosomes which
make up our unique DNA composition.
The cells of our body contain a diploid
number of chromosomes 2n=46.
Our gametes (spermatozoa and oocyte)
contain a haploid number of
chromosomes n=23.

5. Diploid cells Haploid cells
 skin, muscle and
blood cells (somatic
cells)
 Contain two complete
sets of chromosomes
(2n)
 Result of mitosis to
give identical diploid
daughter cells.
 sperm and oocyte
(gametes)
 Contain one complete
set of chromosomes
(n) i.e. half the
number in diploid
cells
 Result of meiotic
division to give 4
unique haploid cells.

6.  Cell life cycle
consists of different
stages
 All our cells go
through a process
called Interphase
which prepares the
cell for division.
 Mitosis
 Meiosis

9.  The two identical chromosomes that
result from DNA replication are referred
to as sister chromatids
 Held together by a centromere which
facilitates movement of chromosomes
during division.

10.  Homologous chromosomes : Similar
in size shape and genetic content.
 Tetrads align at metaphase plate.

12.  Mitosis is the cell division that gives rise
to genetically identical diploid daughter
cells i.e. all our body cells function this
way.
 Meiosis is a special kind of cell division
that happens in our reproductive cells to
give rise to 4 genetically different haploid
daughter cells(gametes); with half the
number of chromosomes.

17.  At 7 months gestation the female embryo
has up to 7 million oogonia. After that
most undergo atresia.
 For the remaining which become the
Primary Oocytes proceed to the beginning
of Meiosis (first meiotic Prophase)and
arrest there until puberty.
 In a women’s lifetime out of the millions
of primary oocytes only 400 become
mature.

18.  Follicular growth and development
(folliculogenesis) is the support system of
oocyte development.
 Cytoplasmic maturation is crucial for
subsequent fertilization and embryo
development.
 Assessed indirectly by cumulus expansion,
expulsion of polar body and increase in
size of perivitelline space (PVS).

19.  Oocyte maturation is triggered by an LH surge
at each menstrual cycle.
 Nuclear maturation involves GV oocyte
progressing to MII (prophase to Metaphase II)
 First visible sign of meiotic resumption
germinal vesicle breakdown(GVBD).

22.  Spermatogenesis consists of 3 phases mitosis
meiosis and spermiogenesis.
 Spermatogonia divide by mitosis they are
diploid and they are the stem cells that give
rise to spermatocytes.
 It occurs in the seminiferous tubules of the
testis.
 The seminiferous epithelium consists of the
germ cells (i.e. spermatogonia spermatocytes
and spermatids) and the Sertoli cells
(somatic).

25.  Day 1 2PN stage
 Day 2 2-4 cell stage
 Day 3 6-8 cell stage
 Day 4 Morula
 Day 5 Blastocyst

26.  Our cells contain 46 chromosomes 23 pairs.
 All cells undergo a cell cycle in preparation
for division.
 Two types of cell division- Mitosis & Meiosis.
 Chromosomes segregation and distribution.
 Spermatogenesis and Oogenesis similarities
and differences.
 Development of the mature spermatozoa
and oocyte.
 Finally fertilization and embryo
development.