Gametogenesis is the process by which mature gametes (sperm or ovum) are formed from primitive germ cells through mitotic and meiotic cell divisions. In males, spermatogenesis occurs in the seminiferous tubules of the testes and produces sperm from puberty until old age. In females, oogenesis begins during fetal development and arrests in meiosis until puberty, when ovulation and formation of ova resumes monthly in the ovaries until menopause. Both processes reduce the number of chromosomes from diploid to haploid and develop the cytoplasmic features necessary for fertilization.

1. Introduction
Dr. Sherif Fahmy

2. Dr. Sherif Fahmy

3. THE BEGINING
Dr. Sherif Fahmy

4. Gametogenesis
•It is the process by which
mature gametes (Sperm or
Ovum) are formed from
primitive germ cells.
Dr. Sherif Fahmy

5. Aim of Gametogenesis
Production of mature male and female
gametes with the following changes:
Nucleus: reduction of diploid number
(46 chromosomes) into haploid number
(23 chromosomes).
Cytoplasm: Increase in size in ova and
markedly reduced in sperms.

6. Two Types of Divisions Occur
During Gametogenesis
•1- Mitotic division.
•2- Meiotic division.

7. MITOTIC DIVISION
Dr. Sherif Fahmy

8. MEIOTIC DIVISION
Dr. Sherif Fahmy

9. Where and
when Sperm or
Ovum are
formed?

10. Sperm Ovum
Where In seminepherou
tubules and
epididymis
In cortex of
ovary and
fallopian tube
When From puberety
till old age.
From intra-
uterine life then
arrested and
completed from
puberty to
menopause.
Gametogenesis

11. MALE GENITAL SYSTEM
Dr. Sherif Fahmy

12. Seminepherous
tubules
Epididymis

13. FEMALE GENITAL SYSTEM
Dr. Sherif Fahm
Ovary
Uterine
tube
Uterus
Vagina

14. Source of Primitive
Germ Cells

15. - Primitive germ cells appear at caudal part of
yolk sac at the 2nd
week.
- Then they migrate to reach developing
gonads (testis in male & ovary in female) at
the 5th
week.
- In males: Primitive germ cells will fill and
block seminephrous tubules in testis and
named spermatogonia.
- In females: Primitive germ cells will be
present in cortex of ovary and named
oogonia.

16. Source of primordial germ cells

17. Spermatogenesis

18. Spermatogenesis
• It is the process by which sperms are formed
from primitive germ cells.
• Site: in seminephrous tubules in testis and
epididymis.
• Time: starting at puberty and continues till old age.
• Aim:
1- Reduction of diploid to haploid number of
chromosomes.
2- Determination of sex of sperms.
3- Giving the sperms the ability to move and fertilize

19. Stages of Spermatogenesis
•A- Spermatocytogenesis.
•B- Spermiogenesis.

20. A- Spermato-cytogenesis

21. Stem spermatogonial
cells
(46 ch)
Sertoli cells
Spermatogonia A (46
ch)
Spermatogonia B (46
ch)
Primary spermatocyte (46
ch)
Secondary spermatocytes (23
ch)
4 sperematids (23 ch)
Sperms
Summary of
Wall of
seminephrous
tubule
Ist meiotic
2nd
meiotic

22. Dr. Sherif Fahmy

23. B- Spermio-genesis

24. Spermatid
Sperm
Nucleu
s
Golgi
apparatus
Mitochondri
a
Shedding of
cytoplasm
Centriol
Axila filament
Acrosomal
cap

25. Seminepherous tubules

26. Abnormal forms of sperms

27. •www.mediafire.com/?
y7e14au9cspg7

28. Oogenesis

29. FEMALE GENITAL SYSTEM
Dr. Sherif Fahm
Ovary
Uterine
tube
Uterus
Vagina

30. Oogenesis: It is a process by which mature
ovum is formed from primitive germ cell
(oogonium).
Site: in cortex of ovary.
Time: Starting in intrauterine life and then
arrested till puberty when it continues till
menopause.
Aim:
1- Reduction of diploid to haploid number.
2- Storage of cytoplasm.
3- Contains only X-chromosome.

31. • Oogenesis passes into 3 stages:
1- Before birth.
2- At birth.
3- From puberty to menopause
(ovarian cycle).

32. Before Birth (Intrauterine life)
At 3rd
month:
-Mitotic divisions of oogonia (46 ch,XX) to increase the
number.
At the 5th
month: the count reaches 7 millions in both ovaries.
Till birth:
Then most of oogonia degenerate, reducing the count.
-the remaining oogonia enlarge to form primary oocytes (46
ch,XX).
-Each primary oocyte starts 1st
meiotic division and arrested
then becomes surrounded by follicular cells to form
Primordial follicles.

33. Primary oocytes arrested in
1st
meiotic division
Single layer of follicular
cells
At birth ovaries contain only
primordial follicles (primary
oocytes arrested in 1st
meiotic
division) surrounded with a layer of
follicular cells
At birth (In the cortex of ovary)

34. At Puberty
FSH & LH
ovarian cycle .
menstrual cycle.
Esterogen &
Progesterone
Pituitary Gland

35. Ovarian Cycle
Dr. Sherif Fahmy
Primordial
follicles
Primary
follicles Graafian
follicle
Ovulation
Ovum (2dry
oocyte arrested
in 2nd
meiotic
division
Corona radiata
Corpus luteum
2dry follicle
Corpus
albicans
Zona
pellucida

36. OVARIAN & MENSTRUAL CYCLES
Dr. Sherif Fahmy

37. FSH
Follicular phase (14
days)

38. Effects of FSH
•Formation of primary and
secondary follicles from
the primordial follicles.

39. Primordial Follicle Primary Follicle
Primary oocyte arrested
in 1st
meiotic division
Single layer of
follicular cells Multiple layer of follicular
cells
FSH

40. Primary Follicle Secondary Follicle
Spaces
Developing
thecal
sheath
Developing
zona
pellucida
FSH

41. Growing 2dry follicle Secondary Follicle
Primary oocyte arrested in
1st
meiotic division Zona pellucida
Granulosa
cells
Crescentic follicular antrum
Theca interna
Theca externa
FSH

42. Secondary Follicle Graafian Follicle
Follicular antrum
Primary oocyte arrested in
1st
meiotic division
Secondary oocyte arrested in 2nd
meiotic division.
LH
FS
H

43. Effects of LH
• 1- Formaton of Graafian follicle.
• 2- Ovulation.
• 3- Formation of corpus luteum.

44. Graafian Follicle
Theca externa
Theca
interna
Stratum
granulosum
Follicular antrum
Cumulus oophorus
Zona pellucida
Secondary
oocyte arrested
in 2nd
meiotic
division

45. Dr. Sherif Fahmy

46. Fate of Graafian
follicleTwo important events occur to the
Graafian follicle:
1- Ovulation.
2- Formation of corpus luteum.

47. 1- Ovulation

48. Steps of Ovulation
LH from pituitary will produce the following
changes:
1- Inceases size of 2dry follicle to form Graafian
follicle.
2- Stimulate collagenase enzyme.
3- Stimulate prostaglandins.
4- Complete 1st
meiotic division of primary oocyte to
form 2dry oocyte (23 ch) and 1st
polar body and start
2nd
meiotic division.
5- Ovulation.
6- Formation of corpus luteum inside the ovary from

49. OVULATION
Dr. Sherif Fahmy

50. Ovulation by Electron Microscope
Dr. Sherif Fahmy

51. Dr. Sherif Fahmy

52. 2- Corpus luteum

53. CORPUS LUTEUM
Dr. Sherif Fahmy
Corpus
albicans

54. Corpus Luteum
• It is the lutenized Graafian follicle under the effect of
lutenizing hormone (L.H.). This occurs in the second half of
ovarian cycle (luteal phase). Yellow pigments are deposited
in granulosa and theca interna cells.
• Corpus luteum produces progesterone hormone which is
responsible for secretory phase of uterine cycle.
• - Fate of corpus luteum:
– No fertilization, it lives for 10 days and the transformed into
fibrous tissue called corpus albicans and stop secreting
progesterone.
– With fertilization, it stays till the 4th month to keep endometrium
intact.
Dr. Sherif Fahmy

55. Differences between divisions
in spermatogenesis and
oogenesis

57. Ovarian Cycle
• 1- Follicular phase : Graafian follicle is formed from
primary follicle under the effect of F.S.H. hormone.
Growing follicle in this phase secretes estrogen
hormone. (from 1st
day to 13th
day)
• 2- Ovulation: rupture of Graffian follicle and release
of 2dty oocyte arrested in 2nd
meiotic division. It is
surrounded by corona radiata and zona pellucida,
under effect of L.H. It occurs at 14th
day .
• 3- Luteal phase: Yellow coloration of ruptured
Graffian follicle (under effect of L.H. ) to form
Corpus luteum. It secretes progesterone and small
amount of estrogen (from day 15 – 28).Dr. Sherif Fahmy

58. Ovarian Cycle
Dr. Sherif Fahmy
Primordial
follicles
Primary
follicles Graafian
follicle
Ovulation
Ovum
Corona
radiata
Corpus luteum
2dry follicle
Corpus
luteum

59. OVARIAN & MENSTRUAL CYCLES
Dr. Sherif Fahmy

60. Uterine (menstrual) Cycle
Esterogen
Progesterone
& esterogenEsterogen
Progesterone and
few esterogen

61. Layers of Endometrium
• 1- Superficial layer
(compact): It contains neck
of glands.
• 2- Middle layer (Spongy):
Edematous layer that
contains body of the
glands.
• 3- Basal layer: Thin layer
that contains fundi of
glands. Responsible for
regeneration. It is not lost
during menstruation.

62. Phases of Uterine cycle
• 1- Menstrual phase (menstruation):
-1st
day of the cycle is the 1st
day of
menstruation.
-It is completed within 3 to 4 days.
-There is loss of non-clotted blood, glands,
blood vessels and endometrial cells (compact
and spongy layers of endometrium).
-It occurs due to spasm of endometrial
arteriols as a result of degeneration of corpus
luteum and drop in level of progesterone.Dr. Sherif Fahmy

63. • 2- Proliferative phase:
• Other names are: follicular,
estrogenic or post-menstrual.
• Endometrium restores its loses and
its thickness becomes 4 mms.
• Glands become longer but straight.
• This phase is under effect of
estrogen.
• It lasts for 10 days. Dr. Sherif Fahmy

64. • 3- Secretory phase:
• -Other names are luteal phase, progestational
or premenstrual.
• -Blood vessels and glands become spiral.
• -Endometrium becomes differentiated into
superficial compact, middle spongy & basal
layers
• -This phase is under effect of progesterone
and small amount of estrogen produced by
corpus luteum.
• -It lasts for 14 days.
Dr. Sherif Fahmy