The document outlines the process of spermatogenesis, starting from spermatogonia during puberty, through meiosis, to the formation of mature sperm. It details the role of Sertoli cells in supporting and providing nutrition to developing spermatocytes, as well as the stages of cellular differentiation that lead to sperm maturation. Additionally, the document mentions the hormonal regulation of sperm production and the time required for each stage of development.

1. Muslima P. Liwalug
BS Biology

2. The process of sperm
production in male
Begins during puberty
Involves meiosis
The 2 cell successive cell
divisions in gamete formation
producing nuclei with half the
full number of chromosome
Occurs in seminiferous
tubules

4. Transverse section of a tubule of
the testis of a rat (X 250).

6. Primitive stem cell
divide by mitosis to
produce more
spermatogonia
Stimulated by FSH
Producing daughter
type A cell and
daughter type B cell

7. daughter type A cell
remain outside blood-
testis barrier and produce
more daughter cells until
death

8. daughter type B cell
becomes primary
spermatocyte
Destined to undergo
meiosis
meiosis I  2
secondary
spermatocytes
meiosis II  4
spermatids

13. In prophase1 pairing and crossing over of
chromosomal segments takes place and genetic
recombination occurs
In metaphase1 homologous pairs arrange on
equator
In anaphase 1 homologous pairs separate to go to
opposite poles
After telophase 1 meiosis I ends and 2 secondary
spermatocytes form each with 23 double
structured chromosomes with X or Y sex
chromosome complement

14. Did
You
know?
It takes about 22
days to complete
meiosis I

15. Meiosis II follows immediately without DNA
replication. Only 23 double structured
chromosomes are involved
2 secondary spermatocytes quickly undergo
meiosis II(Centromeres split in metaphase 2)
end with the formation of 4 spermatids
each with 23 single structured
chromosomes and 1N DNA
2 spermatids bear X chromosome complement
and other two bear Y chromosome complement

16. As steps of spermatogenesis
continue the spermatocytes
progressively move from
basement membrane to the
luminal side of seminiferous
tubule
The cells of Sertoli provide
nutrition and pockets of
support to developing
spermatocytes

17. The spermatocytes in different
stages of development remain
attached by cytoplasmic
bridges
All the spermatocytes are not
in the same stage of
development in the
seminiferous tubules

18. Spermatogenesis:
Luminal progression during
differentiation

19. Spermatids are rounded cells.
They modify to assume specific
shape of the sperm.
They elongate and reorganize
internal structure to acquire
the particular shape.
In spermatogenesis, the
gametes are called spermatids

20. The changes include:
Golgi apparatus
forms acrosomal cap-
proteolitic enzymes
Nucleus is condensed
Centriols make collar
around neck
Microtubules form
flagellum
Mitochondria arrange as
spiral around neck
Excess cytoplasm cast off
as residual body
Cytoplasmic bridges break
and sperms release from
Sertoli cells to lie free in
lumen of seminiferous
tubules

22. A mature sperm has
head, neck and tail
From lumen of
seminiferous tubules
sperms enter duct of
epididymis
They take 20 days to
travel this 4-6 meter
long tortuous duct
If ejaculation does not
occur they die and
degenerate

23. Did
You
know?
About 64-72
days are
required to go
from a
spermatogonium
to be a sperm

24. SPERMATOGENESIS
Pathway of
Sperms

25. GnRH (gonadotropin-releasing hormone)
Secreted by hypothalamus
Stimulates secretion of
anterior pituitary secretion
hormones (FSH/LH)
FSH and LH (follicle stimulating hormone and leuteinizing
hormone)
LH aka as Interstitial Cell Stimulating Hormone
Secreted by anterior pituitary
Directly stimulate the testes
FSH - stimulates formation of ABP (androgen
binding protein) by nurse cells
LH - stimulates interstitial cells to secrete
testosterone

26. Feedback inhibition on
the hypothalamus and
pituitary results from:
Rising levels of
testosterone
Increased inhibin