Adult stem cells maintain tissue homeostasis by balancing selfrenewal and differentiation. In Drosophila females, germline stem cells (GSCs) require Sex lethal (Sxl) to exit the stem cell state and to enter the differentiation pathway. Without Sxl GSCs do not differentiate and instead form tumors. Previous studies have shown that these tumors are not caused by a failure in the self-renewal/ dif...

A 4-year-6 month old boy was seen for sexual precocity manifested by growth spurt, frequent penile erection, penile enlargement and pubic hair development. Scrotal ultrasonography -performed even though the testes were prepubertal, symmetric and bilaterally palpabledisclosed a tumor in the left testis. Left orchiectomy was performed and Leydig cell tumor was detected. Herein, we emphasize the r...

A 29-year old male and his wife presented with an 18 month history of primary infertility. History and initial investigations suggested no major female pathologic component but a semen analysis revealed azoospermia. There was no history of any sexual dysfunction and neither partner was receiving any medication. Clinical examination revealed normal secondary sexual characteristics. Both testicle...

The objective of this review was to describe sexual differentiation events in mammals, relating them to biosynthesis of sexual steroid hormones and their mechanisms of action. Cholesterol is the precursor of sexual steroid hormone biosynthesis via action of several enzymes converting these hormones. Progestagens hormones serve as substrate for the production of androgens, which in turn serve as...

A leucine-rich protein, ARR19 (androgen receptor corepressor-19 kDa), is highly expressed in male reproductive organs and moderately in others. Previously, we have reported that ARR19 is differentially expressed in adult Leydig cells during the testis development and inhibits steroidogenesis by reducing the expression of steroidogenic enzymes. Whereas in prostate, ARR19 represses the transcript...

Lanosterol 14alpha-demethylase (CYP51) produces follicular fluid meiosis-activating sterol (FF-MAS), which is converted further to testis meiosis-activating sterol (T-MAS). MAS are intermediates in the cholesterol biosynthetic pathway, with the ability to trigger resumption of oocyte meiosis in vitro. In contrast to the liver, where pre- and post-MAS genes are upregulated coordinately at the le...

Selenium deficiency is known to be associated with male infertility, and the selenoprotein PHGPx has been shown to increase in rat testis after puberty and to depend on gonadotropin stimulation in hypophysectomized rats [Roveri et al. (1992) J. Biol. Chem. 267, 6142 6146]. Exposure of decapsulated whole testis, however, failed to reveal any transcriptional activation or inhibition of the PHGPx ...

This study investigated the involvement of D-aspartic acid (D-Asp) in testicular steroidogenesis of the green frog Rana esculenta and its effect on stimulation of thumb pad morphology and glandular activity, a typical testosterone-dependent secondary sexual characteristic in this amphibian species. In the testis, D-Asp concentrations vary significantly during the reproductive cycle: they are lo...

What manoeuvres should be included in the physical examination? Physical examination is the key diagnostic man­ oeuvre in boys with undescended testes and should be performed at all well­baby check­ups for male babies, starting at birth.1 The physical examination requires a cooperative baby and a diligent exam­ iner. The child is placed supine, in a frog­legged position, and the examiner uses a...

The effects of maternal exposure to lead (Pb) during the perinatal (1% and 0.1% Pb) periods of sexual brain differentiation were studied in adult male offspring. Maternal Pb levels were measured after treatment. Behavioral (open field and sexual behavior), physical (sexual maturation, body and organ weights), and biochemical (testosterone levels and hypothalamic monoamine and respective metabol...