Postnatal Alterations of Testicular Morphology, Testicular Testosterone Contents and Plasma Hormone Levels in Male Hypogonadic Rat (hgn/hgn)

In order to determine the initial alterations in histopathological and hormonal milieu in the male hypogonadism mutant rats (gene symbol: hgn, a single autosomal recessive trait), postnatal morphological development of the affected testis, and testicular testosterone (T) contents, plasma concentrations of T, follicle stimulating hormone (FSH), luteinizing hormone (LH) and prolactin (PRL) were examined in the hgn/hgn and phenotypically normal male littermates (+/?) on days 0 to 21 after birth. The processes of postnatal differentiation of seminiferous tubules from primitive sex cords; inhibition of germ cells entering mitosis, proliferation and distribution of the Sertoli cells, colonization of the gonocyte and elongation of the tubules, were defective in the hgn/hgn testis. These histopathological alterations were present at birth. These defects might result in the loss of normal spermatogonia, leading failure of spermatogenesis in the adult. Severe progressive degenerations were observed in the tubular diameter and cells within the tubules on day 7 and afterwards, and the affected status seen in the adult was achieved by day 18. There have been marked elevations in the plasma FSH and LH levels from early postnatal age in the hgn/hgn male rat, while testicular and plasma T contents and PRL values were almost comparable between hgn/hgn and +/?.