To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
This chapter discusses the development of the adult population of Leydig cells from the stem cell precursor through the progenitor and immature Leydig cell stages. The morphogenetic events of early testis differentiation are controlled by the Sry (sex-determining region on the Y chromosome) gene. Lack of luteinizing hormone (LH) stimulation results in reduced steroidogenic enzyme activities and in Leydig cell atrophy. As men age, progressive decreases in serum concentrations of testosterone occur. Associated with these decreases are significant health consequences, including reduced sexual function, energy, muscle function, and bone density, and increased frailty and cognitive impairment. A number of hypotheses have been put forward over the years to explain changes that occur in aging cells, including late-onset gene expression, telomere shortening, gene modifications, changes in the immune system, and accumulated reactive oxygen-induced damage to DNA, lipids, and/or proteins.