[The morphogenic effect of gonadotropic hormones on the Leydig cells of the boar testis. II. Effects of administration of chorionic gonadotropin after hypophysectomy. Effects in vivo and in organ culture]. / L'action morphogène des hormones gonadotropes sur les cellules de Leydig du testicule de verrat. II. Effets de l'administration de gonadotropine chorionique aprés hypophysectomie action in vivo et en culture organotypique.

The longer ago the hypophysectomy has been performed, the more marked is Leydig cell atrophy in the testis. The effects of HCG on cellular morphology have been observed in vivo and in organ culture; qualitative quantitative and ultrastructural aspects were studied. In vivo, the effects of a daily injection of gonadotropin on the testis of 2 boars hypophysectomized 3 1/2 months ago are shown. Markedly atrophied cells are strongly stimulated by HCG during the 15 first days (the cell and nucleus recover nearly to standard size, with the typical histological and ultrastructural appearance with all the cell organelles which characterize a functional steroid cell). Then after 1 1/2 month injection it decreases again to the initial state (very small size cytoplasm strongly reduced with very low organelle content). The number of the Leydig cells is maintained during the first 15 days, then it progressively decreases. The effects of HCG on the testicular tissue of 4 boars were studied in organ culture. Interstitial tissue with a greater or lesser degree of atrophy was examined experimentally (1 month, 3 months and 4 months after hypophysectomy) in order to prove a possible irreversibility of the effects of hypophysectomy. In each case, cell changes were studied according to the duration of the culture. Control cultures without HCG in the medium were set up simultaneously. 1 month and/or 3 months after hypophysectomy, the Leydig cells in culture progressively recover the size and the histological and ultrastructural appearances of a typical Leydig cell. After 16 days of culture, the stimulation is highest, as in vivo. The number of Leydig cells is maintained. From the 17th day stimulation decreases and the cell enters a new atrophy phase. In the anhormonal control medium the atrophy continues as long as the culture is maintained, and the number of Leydig cells decreases. 4 months after hypophysectomy, stimulation in culture is still possible during the first 10 days (proved by the same tests); however the size of the cell remains small compared to the normal; then it atrophies again quickly. In this case the hormone does not maintain the number of the Leydig cells. In the control cultures, slight response of the cell is observed, but this effect is limited and disappears a few days later; the number of the cells rapidly decreases. It has been shown that markedly atrophied Leydig cells can highly be stimulated during the first 2 weeks under the influence of HCG as well in vivo as in organ culture. The lability of the effect is not yet explained. 4 months after hypophysectomy, stimulation is not so effective.

[Simultaneous radioimmunoassay of androstenedione, testosterone and dihydrotestosterone. Application to the study of Leydig cell function]. / Dosage simultané, par radioimmunologie, de l'androstènedione, de la testostérone et de la dihydrotestostérone. Application à l'étude du fonctionnement des cellules de Leydig.

A radioimmunological method for simultaneous dosage of androstenedione, testosterone and dihyhydrotestosterone is described. This technique was applied to the study of the secretions of Leydig cells removed from hypophysectomized boar testis, in organ cultures. The releasing kinetic of the 3 steroids under hCG influence was studied; after 12 days of culture, the medium was analysed during 96 hours (8 periods of 12 hours); the steroid production started immediately and showed a progressive increase then slightly slowed down at the end of the 4 days.

[Effect of hCG on the production of androstenedione, testosterone and dihydrotestosterone by long term organ culture testicular tissue from hypophysectomized boars]. / Production d'androstènedione, de testostérone et de dihydrotestostérone par le tissu testiculaire de verrat hypophysectomisé, sous l'action de hCG, en cultures organotypiques de longue durée.

Study of the profile of androstenedione, testosterone and dihydrotestosterone elaboration was performed till 23 days of culture. Stimulation by hCG went through several phases which were expressed in terms of hormonal elaboration by successive steps of 1) progressive initiation 2) strong activity 3) fall 4) renewal of the secretion. The inital step corresponds to the restoration of cytoplasmic organels dealing with steroidogenesis. The fall could correspond to apparition of a transient refractoriness. This late event resembles desensitization which has been described in another models.

[Mitochondrial reorganization after HCG stimulation of Leydig cells from hypophysectomized hogs]. / Réorganisation mitochondriale consécutive à la stimulation par HCG des cellules de Leydig du testicule de porc hypophysectomisé

One to three months after hypophysectomy, porcine Leydig cells contain numerous dense bodies surrounded by a single membrane and crowded with dense rods geometrically arranged. In organotypic culture with HCG they undergo a striking evolution which leads first to intermediate bodies looking like peroxysomes and then to mitochondrial structures. This evolution is quantitatively reduced in a medium without HCG.

[Demonstration of testosterone secretion by testicular tissue of hypophysectomized boar as affected by HCG in organ culture]. / Mise en évidence d'une sécrétion de testostérone par le tissu testiculaire de Verrat hypophysectionisé, sous l'action de HCG en culture organotypique.

Boar Leydig cells undergo a strong atrophy from 1 to 3 months after hypophysectomy but can be reactivated by the gonadotropin HCG in organ culture conditions. This reactivation which appeared at histological and ultrastructural level was evidenced by the capacity of testicular tissue to synthesize testosterone as judged by radioimmunoassay. Both synthesis in the tissue and release into the medium increased according the incubation time with HCG; the adjonction of 17 alpha-OH-pregneolone to culture medium led to increase the intra and extra-tissular concentration of testosterone.

Experimental manipulation of preleukemic change in whole-body irradiated RFM/Up mice (38542).

Radiation which induces leukemogenesis in the unirradiated mouse, inhibits leukemogenesis if given again to the previously irradiated, but not yet leukemic mouse. The objective of this experiment was to identiry nonmalignant late radiation in jury in the bone marrow, the modification of which by a second exposure may account for postponement of radiogenic leukemia. To this end, leukemogenically irradiated RFM/Up mice were reirradiated under conditions known to bring about postponement of the leukemias due to the first radiation exposure. Quantitative analysis of the femoral pone marrow of these mice shows that leukemia incidence is positively correlated with the number of immature myeloid cells, and negatively correlated with the percentage of the mature myeloid cells in the entire myeloid series. The implications of this for the understanding of preleukemic change are discussed.

[Plasma testosterone level and structure of the epididymis and accessory organs of the boar (Sus scrofa L.) after hypophysectomy followed by hCG gonadotropin administration]. / Effets de l-hypophysectomie puis de l'administration de la gonadotropine hCG sur le taux de testostérone plasmatique et sur la structure de l'épididyme et des glandes accessoires chez le verrat (Sus scrofa L.).

Hypophysectomy of the boar resulted in a rapid drop in plasma testosterone level. hCG injections (400 IU/day) considerably elevated testosteronemia (up to 16.41 ng/ml). This effect was obtained either in the days following the operation or several months after (up to 134 days). In the latter case, the effect was temporary because the testosterone level dropped again after 15 days of injections. The sexual target organs (epididymis, seminal vesicle, prostate and Cowper glands) underwent structural change which, in the epithelium, corresponded to fluctuations in testosterone level. These effects were less marked in the cauda epididymis than in other target tissues. In various target organs, the conjunctivomuscular stroma developed after the operation; it did not regress at all, or incompletely, when the epithelia were stimulated indirectly by hCG, and began to hypertrophy when the hCG was no longer effective. Variations in stromal reaction were organ-dependent. When the hCG was administered for more than 14 days, it seemed to have a desensitizing effect; these mechanisms have been discussed.