Testes are the male gonads which have dual function as they produce sperm and also produce some hormones. The Hormones produced by Testes are collctively called Androgens Main Androgen Hormone produced by Leydig cell of Testis is TESTOSTERONE, a steriod hormone its secretion is regulated by pituitary gland

1. PHYSIOLOGICAL
ACTION OF TESTES

2. Testes-an Endocrine gland
The Testes are the male gonads, or
reproductive glands. When stimulated by
the release of pituitary gonadotropins,
these glands produce and secrete the
hormones that control the development of
male sexual characteristics and the
reproductive function of the adult male

3. Hormones produced by Testis
1.Testosterone
 Produced by:
Leydig cells
Regulation:
GnRH from hypothalamus Causes LH
secretion from the pituitary gland which
stimulate the Leydig cells

4. Action
This hormone controls and maintain the
Growth and function of the reproductive
organs.It enhances libido and for
spermatogenesis.

5. 2) Inhibin:
 Produced by:
sertoli cells
 Regulation:
GnRH from Hypothalamus causes
FSH secretion from pituitary gland
which stimulate sertoli cell.

6. Action:
Prevents Secretion of further FSH from
the pituitary gland

7. 3)Oestradiol:
 Produced by sertoli cells
 Regulation:
 GnRH from the Hypothalamus
causes FSH secretion from
the Pituitary Gland which stimulates
the Sertoli Cells.

8. Action
Converted from testosterone, this
hormone's function is complex. It may
prevent apoptosis of male germ cells.

9. Testosterone –The chief
Androgen
Principal Androgen
7mg/day in young but secretion decreases
with age
Like other steriod hormone it is bound to
plasma proteins
A variety of cells, like brain cell, breast can
convert testosterone into estradiol.

10. Testosterone secretion is under control of
LH.
Synthesized by cholesterol in the Leydig
cells and also formed from androstenedione
secreted by adrenal cortex.

11. Mechanism of action -
Testosterone
Penetrates the target cell
Androgen Target cell convert Testosterone
into 5α-dihydrotestosterone(DHT) by 5α
reductase
DHT and Testosterone bind to same
intracellular receptor.
Testosterone receptors-less stable than
DHT

13. Two types of 5α-reductase encoded by
different genes in humans
Type 1 –present in skin Type 2 genital
skin the prostate and other genital tissue
Testosterone Receptor complexes
responsible for maturation of wolffian duct
and male internal genitalia during
development.

14. DHT receptor complexes are needed to
form external genitalia.
DHT receptor also primarily responsible
for enlargement of postate gland and
probably of penisas well as facial hair and
the temporal recession of hairline

15. The Androgen Receptor belong ro subfamily
of steriod hormones receptors.
The Receptor has been cloned and its
sequence is detemined.
Gene for receptor-on Human X chromosome.
Gene comprised of eight exons (A-H) coding
for three specific functionalities.

17. N-Terminal –coded by Exon A. Its function not
clearly defined but may optimize transactivation
capability.
DNA binding domain –encoded by exons B and
C. 66-68 Amino acid sequence. This domain code
for first and second zinc finger motifs.The first
zinc finger -Receptor DNA recognition ,Second -
Dimerization of two receptor molecules during
their assosition with DNA.
The Androgen binding C Terminal -252 amino
acids encoded by exins D-H