C. Perreau

Expression of Maternal Transcripts During Bovine Oocyte In Vitro Maturation is Affected by Donor Age

The primary objective of this study was to compare expression of maternal transcripts in bovine oocyte populations with differential developmental competence: oocytes from prepubertal and pubertal animals; and oocytes from small (3-4 mm) and large (6-10 mm) follicles from pubertal animals. All transcripts were examined in oocytes prior to and after in vitro maturation (IVM). Genes were selected based on their known maternal effect in mouse (ZAR1, STELLA, HSF1, MATER/NLRP5 and its paralogue NLRP9), or their identification as markers of oocyte maturation, either involved in redox metabolism (PRDX1, PRDX2) or meiotic progression (AURKA). Total or polyadenylated forms of the transcripts were followed by reverse transcription coupled to real-time PCR. Six polyadenylated transcripts were found significantly reduced after maturation irrespective of donor age or follicle diameter (p<0.05). Within these six polyadenylated transcripts, ZAR1, NLRP9, HSF1, PRDX1 and PRDX2 were significantly reduced in oocytes from prepubertal animals compared to adult animals (p<0.05). A younger age was also associated with lower abundance (total form) of PRDX2/PRDX1 irrespective of maturation. Total HSF1, PRDX1 and polyadenylated NLRP9 showed a tendency (p values from 0.053 to 0.08) for a higher detection in oocytes from small follicles, thus encouraging further investigation of the follicle diameter model. However, at the present time, follicle size did not significantly affect expression of transcripts examined. In conclusion, this study demonstrates differences in the maternal store of RNA and its regulation during IVM which is dependent on donor age.

Effect of cryptorchidism in the ram: changes in the concentrations of testosterone and estradiol and receptors for LH and FSH in the testis, and its histology

Cryptorchidism was induced in 5 pre-pubertal lambs and 7 adult rams, 5 months after surgery, testicular weight and membrane protein content were 4-fold lower than in the control. The total number of Leydig cells per testis was markedly decreased but their size was not changed. In contrast, the total number of Sertoli cells per testis was not affected but their nuclear size was smaller. Induced cryptorchidism had no effect on the length of seminiferous tubules; blood vessel volume was reduced; and the production of germ cells was completely disrupted. The number of LH receptors estimated per Leydig cell was not changed in pre-pubertal lambs but decreased 4-fold in adult rams. The number of FSH receptors calculated per Sertoli cell was reduced by 95% in both pre-pubertal and adult animals. No effect on the binding affinities of LH (Ka = 1 X 10(10) M-1) and FSH (Ka = 4.5 X 10(9) M-1) to their testicular receptors was observed. Although testicular concentrations of testosterone and estradiol-17 beta were increased, the total content of testosterone within the testis was increased only in pre-pubertal lambs. The estimated ratio of testosterone per Leydig cell was higher in cryptorchid animals than in controls, suggesting that, despite their reduction in number and the decrease of LH receptors, the Leydig cells of cryptorchid rams have an enhanced steroidogenic capacity. This study also confirms the important dysfunction of the Sertoli cells in cryptorchid rams.

Evolution of somatic and germ cell populations after busulfan treatment in utero or neonatal cryptorchidism in the rat

Summary In order to elucidate the respective effects of depletion of germ cells and of increase in testicular temperature, rats of the same Wistar strain were rendered experimentally bicryptorchid or sterilized by a busulfan injection in utero and compared to control animals. In both models, germ cells were depleted but numeric evolution and functions of somatic cells differed. The aim of that work was to compare the numeric evolutions of testicular somatic and germ cells to their respective functions in each model before puberty and in adult rats of the same strain. Serum concentrations of FSH, LH and testosterone were compared at 20, 40 and 110 days of age. Histological analyses of Sertoli and germ cells in the seminiferous tubules and of Leydig cells in the intertubular tissue were performed before puberty and at adulthood. Testosterone serum concentrations were depleted in both models starting at 40 days of age and more in busulfan‐treated rats. Both FSH and LH levels were increased from 20 days onwards in experimental rats. Additional cryptorchidism in busulfan‐treated rats depressed the serum testosterone concentration. At 17 days of age, the cryptorchidism do not modify somatic or germ cell populations while busulfan treatment has induced a decrease of both these populations. Conversely, the cross sectional area of the somatic testicular cells was not affected whatever the treatment. In adult testes of busulfan‐treated and cryptorchid rats, the total numbers of Sertoli and Leydig cells and of germ cells per testis were decreased. The cellular size of the perivascular Leydig cells was not modified by any of the treatments whereas the size of the Sertoli cells was reduced.