Danielle Hélène Garnier

Androgen and estrogen levels in the plasma of Pleurodeles waltl, Michah., during the annual cycle II. Female cycle

Sex steroid levels in the plasma of the female Pleurodeles waltl were determined by radioimmunoassay of blood samples taken monthly from each newt during an 18-month period. Estradiol-17 beta levels were relatively high (greater than 1 ng/ml) but androgen levels were higher (2-30 ng/ml). Androgen and estradiol-17 beta levels fluctuated according to season with two annual peaks, in autumn and in March. Testosterone was the principal androgen present in this plasma. Dihydrotestosterone levels were relatively low but showed slight fluctuations during the year. 4-Androstenedione and estrone levels were very low and relatively constant throughout the seasons. Fluctuations of androgen and estradiol-17 beta levels were synchronous between the several newts studied during the year. The ratio [E2-17 beta]/[Androgen] was stable during the major part of the year (0.2-0.3) except in July and August, when it reached the value of 1.0. The seasonal variations in the steroid levels were well correlated to the morphological modifications of sexual characteristics during the year.

Seasonal variations of androgens, estrogens, and progesterone in the different lobules of the testis and in the plasma of Salamandra salamandra

Progesterone, 4-androstenedione, testosterone, dihydrotestosterone, 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol), 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol), estrone, and estradiol levels were determined by radioimmunoassay in the different lobules of the testis of Salamandra salamandra throughout the year according to the seasonal cycle. 3 beta-diol levels were not detectable. High levels of steroids were found in the grandular tissue (enlarged pericystic cells after spermiation) and large variations were showed for progesterone, 4-androstenedione, testosterone, 3 alpha-diol, and estrone. In the mature lobule (formed by cysts with mature spermatozoa), only testosterone showed seasonal variations and in the immature lobule (with early stages of meiosis), 3 alpha-diol showed fluctuations. The major estrogen found in the testis of Salamandra was estrone; estradiol stayed at a low level throughout the cycle. The steroids fluctuation seems to be related to the histological evolution of the testis throughout the cycle. The present data were the first on steroid seasonal variations in the testis of an urodele.

The Dialogue Between Late Spermatids and Sertoli Cells in Vertebrates: A Century of Research

In the nineteenth century, the relationship between spermatids and Sertoli cells had already attracted the attention of scientists (histologists) and much passionate debate. In his review of 1901, Regaud noted that earlier authors, such as von Ebner, Sertoli, Benda had observed the development of a “substantial union” between elongating spermatids and Sertoli cells. Benda (1887) and von Ebner (1871, 1888) developed the basic concepts of “copulation” and “spermatoblast” (symbiotic relationship) respectively, to characterize the relationship between late spermatids and Sertoli cells. The controversy whether this was true “copulation” (i.e. cytoplasmic continuity between the cells), only ended when Burgos and Fawcett (1955), using the electron microscope, clarified details of the boundary relations between spermatids and Sertoli cells (Roosen-Runge 1962).

Induction of Maternal Behavior in Incubating and Non-Incubating Hens: Influence of Hormones

Maternal responses and variations in plasma levels of prolactin and testosterone have been studied in incubating and in non-incubating, non-laying hens during forced adoption experiments. The results demonstrate the ability of incubating hens to display complete maternal behavior as early as the 10th day of incubation after being exposed to stimulation by chicks during one night. Maternal responses also emerged in non-laying hens but more gradually. In both groups, a decline in plasma testosterone occurred after the introduction of the chicks and, in the incubating hens, prolactin levels fell as they abandoned their nests.

Induction of maternal behavior and some hormonal and physiological correlates in the domestic hen.

The manifestation of maternal behavior and the variations of plasmatic levels of gonadic hormones (testosterone, delta 4-androstenedione, and 17 beta-estradiol) have been studied in two groups of domestic hens (layers and nonlayers) during a forced adoption experiment. Maternal behavior appears later in actively laying hens than in nonlayers. The former hens show a higher level of androgens (T and delta 4). The appearance of typical maternal behavior coincides with a pause in laying and a decrease in all the plasmatic steroid levels measured.

Studies of the androgen binding protein in the rete testis fluid of the ram and its relation to sexual season

An androgen binding protein (ABP) with an electrophoretic mobility (Rf) of 0.56 is present in the rete testis fluid of adult rams. Its steroid specificity was found to be in the following order: 5alpha-DHT, testosterone, oestradiol-17 beta, dehydroepiandrosterone 5beta-DHT, androstenedione, cyproterone, cyproterone acetate, cortisol and progesterone. The characteristics of the ABP are similar to those found for the ABP of the testis and the epididymis of the rat and the rabbit. The concentration of ABP, determined by the dextran-coated charcoal method and sometimes confirmed by the steady-state polyacrylamide gel electrophoresis method, was significantly higher in the breeding season than in the non-breeding season (4.40 +/- 0.98 X 10(-9) M vs. 2.60 +/- 0.62 X 10(-9) M; P less than 0.037). The affinity constant of the ABP was independent of the season (2.45 +/- 0.21 X 10(9) M-1 vs. 2.66 +/- 0.1 X 10(9) M-1; NS). In addition, ABP was positively correlated with 5alpha-DHT (r = 0.506; P less than 0.0009), testosterone (r = 0.445; P less than 0.0003), total protein (r = 0.329; P less than 0.02) and spermatozoa (r = 0.406; P less than 0.006) in the RTF and with blood plasma testosterone (r = 0.584; P less than 0.0001). Furthermore, testosterone and 5alpha-DHT in RTF were positively correlated (r = 0.582; P less than 0.0001). These androgens were also correlated with plasma testosterone (r = 0.262, P less than 0.052 for testosterone in RTF; r = 0.341, P less than 0.018 for 5 alpha-DHT). Total proteins and spermatozoa were found to be positively correlated in the RTF (r = 0.789; P less than 0.0001).

Comparative plasma levels of androgens and 17β-estradiol in the diploid and triploid newt, Pleurodeles waltl

Seasonal changes in the plasma levels of androgens (testosterone plus dihydrotestosterone) and 17 beta-estradiol in diploid and triploid adult newts, Pleurodeles waltl were studied. In both male and female diploid individuals, large variations were reported with highest levels being found during breeding periods. In triploid newts seasonal variations were also found, similar to the diploid ones, but the plasma concentrations of the 17 beta-estradiol and androgens in triploid females and androgens in triploid males were lower throughout the year than those reported for the diploids. This difference is discussed in relation to the genetic sexual constitution.

Influence of food restriction and of the presence of chicks on the reproductive system of the domestic hen.

An experiment was conducted with 4 groups of hens: a control group of laying hens, a group subjected to food deprivation for 7 d, a group subjected to food deprivation for 7 d, then re-fed for 10 d and a group subjected to food deprivation for 7 d then re-fed for 10 d with two chicks per hen introduced during the last 7 d of refeeding. Food deprivation provoked the involution of the oviduct and ovarian regression, as well as a decrease in the plasma concentrations of luteinising hormone (LH) and sex steroids (progesterone, testosterone and oestradiol). After 3 d of re-feeding, there was a significant increase in the plasma concentrations of LH and steroid hormones. This phenomenon was even more marked after 10 d of re-feeding; most of the hens of the third group which were not given chicks, were at the point of lay. The presence of chicks resulted in the expression of maternal behaviour and suppressed a rapid return to laying. This was especially marked in hens showing typical maternal behaviour traits, for which the morphological and endocrine measurements indicated a decrease in the activity of the hypothalamo-hypophyseal-gonadal axis.

The dynamics of the steroidogenic response of perifused Xenopus ovarian explants to gonadotropins

Steroid release before and during maturation was studied in Xenopus ovarian follicles under various conditions of stimulation of LH in a perifusion system. Acute stimulation by 15 micrograms of LH induces a 10-fold increase in the androgen (testosterone and androstenedione) level which reaches a maximum 4 hr later and then slowly decreases until the 25th hour. Repeated stimulations every 2 or 4 hr are followed by the same androgen increase during the first 8 or 10 hr and then by a slow decrease in the secretion despite new LH injections. A significant increase in progesterone secretion is seen only after at least two stimulations (8 hr). Estradiol secretion slowly increases to a moderate level during the first 5 hr and then remains stable whatever the stimulation. During continuous stimulation (LH 0.5 microgram/ml) androgen levels reach an initial maximum after 4 hr and then fluctuate with a 2-hr period. Addition of theophyllin to the medium enhances these fluctuations. After 12 hr when the progesterone has increased, androgen secretion diminishes to reach a basal level without fluctuations. Germinal vesicle breakdown occurs only in follicles that have been appropriately stimulated to secrete androgens and progesterone during the required time.

Seasonal variations of androgens and of several sexual parameters in male Meriones shawi in southern Morocco

Seasonal changes of several parameters related to sexual activity were studied in the gerbil (Rodentia: Gerbillidae). The weight of the testes, seminal vesicles, and adrenals fluctuate throughout the year. Plasma androgen levels and histological aspect of the testes also vary throughout the year. Spermatogonial and steroid activities are synchronous and are maximal in winter and spring. The relationship between these activities and environmental climatic parameters is discussed: the beginning of sexual activity seems correlated with the first rains.