Plasma and tissue testosterone concentrations were determined by radioimmunoassay in 12 eight-month-old sexually mature New Zealand White rabbits and evaluated for possible associations with spermatogenic efficiency as well as with volume density and number of Leydig cells. Testicular tissue was processed histologically and histometry was performed in order to quantify germ cells, Sertoli cells...

Male aging is accompanied by reduced testosterone production by the Leydig cells, the testosterone-producing cells of the testis. The mechanism by which this occurs is unknown. Based on the observations that reactive oxygen is capable of damaging components of the steroidogenic pathway and that reactive oxygen is produced during steroidogenesis itself, we hypothesized that long-term suppression...

Leydig cells undergo apoptosis in response to the cytotoxin ethane dimethanesulfonate (EDS), with numbers declining at 12-18 h and maximal apoptosis at 24 h postinjection. The Bcl-2 family members, Bcl-2, Bcl-xl, and Bax, appear not to be involved in this process. To further investigate this phenomena, a single dose of EDS was administered to adult rats to induce the killing of Leydig cells. Th...

The testes of the monkey, Macaca fascicularis, from birth to adulthood and of rats from puberty to adulthood were examined by both light and electron microscopy to estimate the mitotic activity of the Leydig cells. In monkeys, mitotic activity was measurable only in neonates: 2.3% in Leydig cells and 0.4% in fibroblast-like cells. From measurements of 3H-thymidine incorporation, mature Leydig c...

A number of studies have indicated that testicular macrophages play an important role in regulating steroidogenesis of Leydig cells and maintain homeostasis within the testis. The current paper deals with macrophages (CD68 positive cells) and Leydig cells in patients with nonobstructive azoospermia (NOA). Methods employed included histological analysis on semi- and ultrathin sections, immunohis...

Cultured Leydig cells exhibited time-dependent decreases in the microsomal cytochrome P-450 enzyme activities, 17 alpha-hydroxylase and C17-20 lyase when maintained under standard culture conditions (95% air, 5% CO2). Inclusion of the hydroxyl radical scavenger dimethyl sulfoxide in the culture medium, or the reduction of oxygen tension from 19 to 1% O2 was effective in preserving these enzyme ...

AIM To determine the androgenic effects of Basella alba and Hibiscus macranthus extracts in the rat and the bull, and to develop a novel in vitro test system using Leydig cells from bull testes. METHODS The effect of methanol extracts from both plants on testosterone production in isolated Leydig cells from the rat and the bull was analyzed using 125I-radioimmunoassay (125I-RIA). Rat Leydig c...

This study investigates the relationship between the high density lipoprotein (HDL) receptor (scavenger receptors, SR-BI and SR-BII), selective lipoprotein-cholesteryl ester uptake, and testosterone production in Leydig cells of control, hypocholesterolemic and gonadotrophic hormone (hCG) treated rats. Leydig cells from mature control rats show poor efficiency in incorporation of labeled HDL-ch...

During testicular development, fetal and adult populations of Leydig cells arise sequentially. Previous studies have shown that androgen action is required for normal steroidogenic activity in the mouse testis. Therefore, to determine the role of androgens in regulating fetal and adult Leydig cell differentiation and function, Leydig development has been measured in mice lacking functional andr...