Thermostat

1
Feedback Loops
(-)
Thermostat
electricity
Heat
()
Furnace
Igniter
spark
()
Negative Feedback System
2
Feedback Loops
Hypothalamic-Pituitary-Testicular Axis
(-)
Hypothalamus
GnRH
Testosterone and Inhibin
()
Pituitary
Testis
FSH and LH
()
3
Why does the testis produce testosterone?
How could we find out?
Experiments
Castration
Pituitary cells LH
Secondary Sex Chracteristics
Neutralize LH with LH antibodies
Pituitary cells
Secondary Sex Chracteristics Testis Size
Tx with testosterone
LH Testis Size
4
Testicular Histology
Scanning Electron Micrograph
Seminiferous Tubules
Light Micrograph
Interstial Tissue
5
How is the seminiferous tubule organized?
6
Comparative Diagram
7
Spermatogenesis
8
What is the function of the spermatogonia?

• Clonal expansion

9
Spermiogenesis Spermatid Differentiation
10
Staging the Seminiferous Epithelium
11
Male Reproductive Tract