Results from studies in rodent are in broad agreement with those in humans and indicate that functional maturation of Leydig cells occurs after formation of MIS-positive seminiferous cords and that AR immunoexpression is not detectable in the nuclei of Sertoli cells or Leydig cells during fetal life.
Immunolocalization of proteins expressed in the germ cell population revealed that although germ cells in the first trimester appeared to represent a largely homogeneous population, in the second trimester a number of distinct subpopulations were present. canadian neighbor pharmacy
The CHK2-positive cells were identified in both first- and second-trimester samples; some first-trimester samples were immunonegative, suggesting that expression of this protein may be switched on at the time of cord formation. CHK2 is a serine/threonine kinase component of the S and G2/M replication checkpoint that may be involved in cell-cycle arrest in response to DNA damage. CHK2 is also expressed in adult germ cells, but it is rapidly down-regulated as they enter meiosis. In fetal life, expression of CHK2 in most germ cells may reflect an important role in the maintenance of the genomic integrity of the germ line. The majority of germ cells in the first-trimester testes appeared to be PLAP positive; however, in the second trimester, PLAP-positive cells were rare.