Spermatogenesis

2. Q. Write an essay
on spermatogenesis.

3. Total mark = 07
Spermatidogenesis = 03
Spermiogenesis = 01
Labeled diagram = 03

4. INTRODUCTION
Human beings are most
evolved with well marked sexual
dimorphism. Puberty is the
maturity age marked by separate
male or female secondary sex
characters due to secretion of
respective sex hormones in gonads
guiding respective gametogeneeis.

5. GAMETOGENESIS
It is the process of
production of male /
female gamete(s) in
respective gonads under
hormonal control.

6. TYPES OF GAMETOGENESIS
It may be of two types :-
Spermatogenesis in male
producing sperms in
seminiferous tubules of testes.
Oogenesis in female
producing ovum in ovary.

7. SPERMATOGENESIS
It is the process of production of
SPERMATOZOA / SPERM
from primary germ cells in
seminiferous tubules of testes
under stimulation of
TESTOSTERON secreted by
LEYDIG cells of testes at
puberty.

8. STEPS OF SPERMATOGENESIS
 Spermatidogenesis
 Multiplication Phase
 Growth Phase
 Maturation Phase
→ 1st Maturation Phase
→ 2nd Maturation Phase
 Spermatoleosis/Spermiogenesis

9. EXTRA RELATED POINTS
 Hormonal Regulation of
spermatogenesis
 Conclusion

10. SPERMATIDOGENESIS
It is the process of
production of four
spermatids from one primary
germ cell after multiplication,
growth and maturation
phases.

11. MULTIPLICATIION PHASE
(Primary Germ Cell to Spermatogonia)
In this phase deploid (2n) Primary
germ cells of testis divide by repeated
mitosis to produce clones called
Spermatogonia (spermatogonium –
singular) or Sperm mother cells under
stimulation of testosterone from leydig
cells.

12. GEOWTH PHASE
(Spermatogonium to Primary Spermatocyte)
In this phase deploid (2n)
Spermatogonium do not divide but
grow and become large called
Primary Spermatocyte being
nourished by Sertoli cells of
seminiferous tubules.

13. 1ST MATURATION PHASE
(Primary Spermatocyte to
Secondary Spermatocyte)
In this phase, one deploid (2n)
Primary Spermatocyte divides by
meiosis – I to produce two haploid
(n) Secondary Spermatocytes. It is a
reductional division.

14. 2ND MATURATION PHASE
(Secondary Spermatocytes to Spermatids)
In this phase, both haploid (n)
Secondary Spermatocytes divides
by meiosis – II to produce four (two
from each) haploid (n) Spermatids.
It is a equational division.

15. SPERMIOGENESIS
(Spermatids to Spermatozoa)
In this phase, the non motile,
round Spermatids are converted
into motile, elongated and energetic
Spermatozoa.

16. CHANGES DURING SPERMIOGENESIS
Round, non motile Spermatid
changes into elongated, motile
spermatozoa having head,
neck, middle piece and tail.
Large, central, round nucleus
become elongated, smaller (by
loosing water) and occupy
much of the head.

17. CHANGES DURING SPERMIOGENESIS
Golgi bodies condensed,
become Acrosome and placed
above nucleus in head.
Cytoplasm loose much of
water and become thin and
strip around head and sides of
neck outer to nucleus,
acrosome and centrioles.

18. CHANGES DURING SPERMIOGENESIS
Centrioles divide into three
Proximal centriole – below
nucleus, in neck. It is donated to
secondary oocyte to start
second maturation division of
oogenesis and further processes.
Distal centriole – below
proximal centriole to form axial
filaments of sperms.

19. CHANGES DURING SPERMIOGENESIS
Ring centriole – at the junction of
middle piece and tail. Its function
is unknown.
 Mitochondria form a spiral
structure in middle piece around
axial filaments to provide energy to
sperm.
 Axial filaments form main tail.
 Entirely sperm is covered by plasma
membrane.

21. HORMONAL
REGULATION

22. HYPOTHALAMUS
(BRAIN)
GONADOTROPIN
RELEASING FACTOR
PITUITARY GLAND

23. PITUITARY GLAND
FSH
(FOLLICLE
STIMULATING
HORMONE)
LH
(LUTEINIZING
HORMONE)

24. FSH LH
STIMULATES
DEVELOPMENT OF
SEMINIFEROUS
TUBULES
LEYDIG
CELLS
DEVELOPMENT OF
GERMINAL AND
SERTOLI CELLS
TESTOSTERONE
SPERMATOGENESIS TO PRODUCE SPERMATOZOA

25. Spermatogonia or
Sperm mother cell
Primary Spermatocyte
Multiplication
Phase
Growth Phase

26. Secondary Spermatocyte
Spermatid
1st Maturation
Phase
2ndMaturation
Phase

27. Spermatid
Spermatozoa
Or
Sperm

28. SIGNIFICANCE OF SPERMIOGENESIS
It produce haploid, elongated,
motile sperms from deploid
germ cells to fertilise haploid
ovum in female forming
deploid zygote in sexual
reproduction.
It restores deploid chromosome
number in offspring.

29. CONCLUSION
Males produce Sperms by
spermatogenesis. These are
discharged with semen into
female reproductive tract during
orgasm of coitus for probable
fertilisation, pregnancy and child
birth for continuity of race on
earth.