The document summarizes conception and fertilization. It describes the maturation process of both male and female gametes. Spermatogenesis produces sperm from male germ cells, while oogenesis results in a mature ovum. Ovulation releases a secondary oocyte from the ovaries. Fertilization occurs when a sperm fuses with the ovum in the fallopian tubes, restoring the chromosome number and initiating embryonic development. This forms a zygote containing a mix of paternal and maternal genetic material.

1. Conception and Fertilization
By:
Haider Mohammed

2. 


FemaleMale
OvumSpermatozoon
Maturation process

3. Both mitosis and meiosis play a role in
gametogensis.
Mitosis provide the precursor cells.
Meiosis bring about the reduction division
that result in gametes.

5. Gametogensis
SpermatogenesisOogenesis

7. Fully matured ovum:
Largest cell in the body, 130 micron in diameter Cytoplasm 23
chromosomes (23 x)

8. The process involved in the development of
spermatids from the primordial male germ cells and
their differentiation into spermatozoa is called
spermatogenesis

9.  It has got two parts, a head
and a tail
 The head:
- Condensed nucleus and
acrosomal cap.
- Acrosome is rich in enzymes.
 The tail:
- Divided into four zones (the
neck, the middle piece, the
principle piece and the end
piece.

10. Spermatogensis differ from oogensis in
three ways:
1- All four product of meiosis develop into
sperm while only one of the four become
an egg.
2- spermatogensis occur throughout
adolescence and adulthood.
3- sperm are produce continuously without
the prolonged interruption like in
oogenesis.

11. Ovulation is a process where by a
secondary oocyte is released from ovary
following of a mature graafian follicle and
become available for conception.
In each ovarian cycle, only one secondary
oocyte is likely to rupture.
It starts at puberty and end menopause.

13. Preovulatory enlargement of the graafian
follicle due to accumulation of follicular fluid.
Measure about 20 mm in diameter.
The cumulus oophorus sprates from rest of
granulosa cells.
The follicular wall near the ovarian surface
becomes thinner.

14. Significant changes occur just prior to
ovulation (few hours).
Cytoplasmic volume is increased.
Completion of the arrested first meiotic
division occur with extrusion of first polar
body, each containing haploid number of
chromosomes (23 X).

15. Endocrinal (LH surge, FSH rise)
Stretching factors (a passive stretching
process of granulosa cells).
Contraction of the micromuscles in the
theca externa and ovarian stroma due to
increase prostaglandin secretion.

16.  LH surge: sustained peak level of estrogen for 24 to 36 hours
in the late follicular phase.
 LH surge occurs from the anterior pituitary.
 Ovulation approximately occurs 16-24 hours after the LH
surge.
 LH peak persist for about 24 hours.
 The LH surge stimulates completion of reduction division of
the oocyte and intiate luteinization of the granulosa cells,
synthesis of progesterone and prostaglandins.
 FSH rise: preovulatery rise of progesterone facilitate the
positive feed back action of estrogen to induce FSH surge
lead to increase plasminogen activator. Plasminogen help
lysis of the wall of the follicle.

17. The follicle is changed into corpus luteum.
The ovum is peaked up into the fallopian
tube and undergoes either degeneration or
further maturation, if fertilization is to occur.
Menstruation is unrelated with ovulation.

18. Fertilization is a process of fusion of the
spermatozoon with the mature ovum.
It begins with sperm egg collision and ends
with production of mononucleated single cell
called the zygot.
Objectives:
1- To initiate the embryonic development of the
egg.
2- To restore the chromosome number of the
species.

20. Fertilizable life span of oocyte is 12 to 24
hours and sperm is 48 to 72 hours.
Out of the hundreds in the vagina at single
ejaculation, only thousands capacitated
spermatozoa enter the uterine tube while only
300-500 reach the ovum.
Tubal transport is facilitated by muscular
contraction and aspiration action of the
uterine tube.
It take only few minutes for sperm to reach
the fallopian tube.

21. Capacitation
Acrosomal reaction
Cortical reaction
Development of Zygote

22. The process of undertaking in the sperm
when inside the female genital tract
influenced by the secretion of the uterine tube
is know as capacitation.
Sperm must be in the female genital tract
4-6 hours before they can fertilize an ovum.
The sperm undergoes changes in the removal
of the glycoprotein coat.

23. The acrosomal layer of the sperm becom
reactive and release the enzyme
hyaluronidase known as the acrosome
reaction.
It disperses the corona radiate (outer layer
of ovum) allowing access to the zona
pellucida.

24. The first sperm that reaches the zona
pellucida penetrates it.
Penetration of the zona pellucida occur with
the aid of several enzymes processed by the
sperm which break down the proteins of the
zona layer.
Upon penetration a chemical reaction know
as the cortical reaction occur which makes it
impermeable to other sperms.

25. The plasma membrane of the sperm and
oocyte fuse.
The ocyte at this stage compelet and
second meiotic division and becomes
mature, the pronuclei has 23 haploid
chromosomes.
Male and female pronuclei fuses to form a
new nucleus that is a combination of the
genetic material from both the sperm and
the oocyte diploid cell

26.  The male and female gametes each contribute
half the complement of the chromosomes to
make a total of 46. the new cell is called zygote.
 The zygote, thus formed, contain both the
paternal and maternal genetic materials.
 Sex of the child is determined by the pattern of
the sex chromosome supplied by the
spermatozoon
 If the spermatozoon contain X chromosome, a
female embryo (46,XX) is formed, if it contain a
Y chromosome , a male emberyo (46, XX) is
formed.

27. Pre-embryonic period: first two
weeks after fertilization.
Embryonic period: 2 – 8 weeks.
Fetal period: 8 Weeks to birth

28.  This period include the implantation of the
zygote into the endometrium.
 The embryo takes about 3 days to travel
through the fallopian tube to reach the uterus.
 It takes another 3 days to get implanted,
usually in the dorsal wall of the uterus.
 Thus embryo is about 1 week old when it gets
implanted.
 Zygote undergo mitotic division and cellular
replication known as cleavage which result in
the formation of smaller cells known as
blastomers.

29.  During this period a strong membrane of
glycoprotein called zona pellucida surrounds
the zygote
 The zygote mainly gets nourishment
(glycogen)from the goblet cells of the uterine
tubes and later the secretory cells of the
uterus.
 The zygote divided in to :
 2 cells at day 1,or 30 hours
 4 at 2 days,8 by 2.5 days,16 by 3 days and
called as morula resembling a mulberry 16 to
64 cell stage

31. Cell bind tightly together in a process
known as compactation.
Next cavitation occur where by the
outermost cells secrete fluid into the
morula and a fluid filled cavity or blastocele
appears.
This result in the formation of the blaster or
blastocyst comprising 58 cells.

32. Development of the morula to the blastocyst
has occurred by day 4.
Blastocyst
Trophoblast
Placenta
Chorion
Inner cell mass
Fetus
Amnion
Umbilical
cord

33. Embedding of the embryo to the wall of
uterus.
Also called as Nidation.
Occurs in the endometrium of the anterior
or posterior wall of the body near the
fundus on the 6th day which corresponds to
the 20th day of regular menstrual cycle.
Implantation occur through four stages
apposition, adhesion, penetration and
invasion.

34. Occurs through pinopod formation.
Pinopods are long finger like projections
(microvilli) from the endometrial cell
surface..
This pinopods absorb the endometrial fluid
which is secreted by the endometrial gland
cells. This fluid, rich in glycogen and mucin
provides nutrition to blastocyst intially.

35. Unless this fluid is absorbed, adhesion
phase cannot occur.
Adhesion of blastocyst to the endometrium
occurs through the adhesion molecules like
integrin, selectin and cadherin
(glycoproteins).

36. Occur through the stromal cells in between
the gland and is facilitated by the histolytic
action of the blastocyst.
With increasing lysis of the stormal cells,
the blastocyst is burrowed more and more
inside the stratum compactum of the
decidua.

37. Endometrium during pregnancy is know as
the decidua.
Three layer are found.
1- the basal layer: lie immediately above the
myometrium. Remain unchanged in itself but
regenerates the new endomertium during the
puerperium
2- the functional layer: consist of tortuous
glands which are rich in secretions.

38. It provide a secure anchorage for the
placenta and allows it access to nutrition and
oxygen, but as soon as the baby is born
separation can occur.
3- The compact layer: this layer form the
surface of the decidua and is composed of
closely packed stroma cells and the neck of
the glands.

39. Three layer include:
1- The ectoderm: skin and nervous system
2- The mesoderm: bones, muscles, heart,
blood vessels and some visceral organs.
3- The endoderm: mucous membrane and
glands.
Two cavities appear on either side of
embryonic plate (amniotic cavity and yolk
sac)

40.  By the end of 2nd month, trophoblast is
character by great no. of secondary and
tertiary villi.
 By four month cytotrophblastic cells and
connective tissue disappear, only syncytium
and endothelial vessel remain (tertiary villi).
 In early stage, villi covers the entire surface of
chorion.
 As the pregnancy advances, villi on
embryonic pole continues to grow and
expand – chorion frondosum (bushy chorion).

41.  Villi on an embryonic pole degenerate- chorion
leave. The fusion of amnion and chorion occurs to
form aminochorionic membrane.
 Placenta is an organ that connects the developing
fetus to the uterine wall to allow.
 Nutrient uptake.
 Waste elimination.
 Gas exchange by the mother blood supply.
 Hormone production.
 Formation of a barrier.
 Function as a fetomaternal organ with 2
components (fetal placenta and maternal placenta).

42. Sugar, fats and oxygen diffuse from mothers
blood to fetus.
Urea and CO2 diffuse from fetus to mother.
Maternal antibodies actively transported
across placenta. Some resistance to disease
(passive immunity).
Most bacteria are blocked.
Many viruses can pass including rubella,
chickenpox, sometime HIV.
Many drugs and toxins pass including
alcohol, heroin and mercury.

43. Progesterone and HCG (human choroinic
gondatropin, the hormone tested for
pregnancy): maintain the uterus.
Estrogen and CRH (corticotropin releasing
hormone): promote labor.