The effect of hCG on the human body is similar to luteinizing hormone. It also signals, passing through the pituitary gland, about the active stimulation of testosterone. 

HCG in the form of a drug, in addition to increasing the production of the male hormone, enhances the quality properties of sperm, makes secondary sexual characteristics in both women and men much more pronounced. 

In female representatives, chorionic gonadotropin enhances the synthesis of progesterone, significantly enhances the rate of egg maturation. https://steroidssp.com/t/post-cycle-therapy/gonadotropin/ In addition, this drug has developed the placenta.

The amount of hCG produced allows you to regulate the feedback in the chain of the axis of the hypothalamus-pituitary-testicles axis. 

Chorionic gonadotropin deficiency provokes a decrease in the size and functionality of the testicles.

The artificial administration of both synthetic testosterone and its various analogs allows the increase in the concentration of this human hormone, which allows the hypoghalamo-pituitary-gonadal system to understand without the need to synthesize gonadotropin and gonadoliberin. This provokes the testicles to lose their functions, which become much smaller.