Elucidation of the role of LH and FSH during neonatal testicular development and growth in the boar.

The aim was to elucidate the role of LH and FSH in testicular development and growth in the neonatal boar. On Day 10 after birth (Day 0 of study), animals were assigned to one of nine groups (n=6): Group 1, control, no treatment; Group 2, hemicastrated (H); Group 3, H and implanted with GnRH agonist (H+GnRH); Group 4, H+GnRH+FSH 200µg/kg daily from Days 0 to 14 (D0-14); Group 5, H+GnRH+FSH 400µg/kg D0-14; Group 6, H+GnRH+FSH 400µg/kg in PVP D0-14; Group 7, H+GnRH+LH 200µg/kg D0-14; Group 8, H+GnRH+LH 400µg/kg D0-14; Group 9, H+GnRH+LH and FSH 200µg/kg D0-14. The right testis in control and hemicastrated boars was removed on Day 15. Hemicastrated boars had greater (P<0.05) testicular growth than control boars and testicular growth was prevented in boars treated with GnRH agonist. FSH induced Sertoli cell proliferation but not testicular growth whilst LH induced Leydig cell proliferation and testicular growth was similar to control boars but less than hemicastrated boars. LH+FSH induced similar testicular growth as LH alone and neither LH and/or FSH supported testicular hypertrophy in hemicastrated boars. The findings show conclusively for the first time that LH and FSH respectively induce Leydig cell and Sertoli cell proliferation in the neonatal boar. LH additionally supports a normal increase in testicular size in the neonatal boar.

Expression of FGF2 and TGFalpha and testis morphology during testicular hypertrophy subsequent to hemicastration in the neonatal boar.

The objective was to ascertain fibroblast growth factor-2 (FGF2), epidermal growth factor (EGF), and transforming growth factor-alpha (TGFalpha) mRNA expression and testis morphology during accelerated testicular growth after hemicastration in the neonatal boar. On Day 10 after birth (Day 0), boars were assigned to control (n = 28), no treatment; hemicastrated (n = 28), left testis removed. The right testis in both groups (n = 7) was removed on Days 5, 10, 15, and 20. Expression of mRNA for FGF2, EGF, and TGFalpha was determined by qRT-PCR using TaqMan. Testicular morphology was determined on Day 15. On Day 10, hemicastrated boars had a greater (P = 0.01) testis weight (6.2 +/- 0.8 g; mean +/- SEM) than controls (4.3 +/- 0.4 g) and on Day 15 testis weight in hemicastrated boars (8.8 +/- 0.8 g) was twice (P < 0.01) that of control boars (4.2 +/- 0.3 g). Seminiferous tubule volume was approximately doubled in hemicastrated boars (P < 0.01) and was associated with an increase (P < 0.01) in Sertoli cell number. Interstitial compartment volume was greater (P < 0.01) in hemicastrated boars. Leydig cell numbers were similar (P = 0.14) but volume was greater (P < 0.01) for hemicastrates. There were no differences (P > 0.05) between control and hemicastrated boars in TGFalpha or FGF2 expression on Day 5 or Day 10, and EGF was not detected. It was concluded that upregulation of TGFalpha or FGF2 expression is not a pre-requisite for enhanced testicular growth and increased Sertoli cell proliferation that occurs subsequent to hemicastration in the neonatal boar.

The effect of spinal anaesthesia on urethral function.

This study was to assess the effect of spinal anaesthesia on urethral retro-resistance pressure (URP), cough pressures and tendency to leak. The population consisted of 32 women undergoing a tension-free vaginal tape (TVT) operation under a spinal anaesthetic. URP, cough pressures and an assessment of the degree of leak were performed before the spinal anaesthetic was placed. A standard anaesthetic technique was used, and measurements were repeated after the spinal anaesthetic was inserted. The degree of leak was assessed on a five-point scale with 350 ml in the bladder. The cough pressures and URP values were averaged over three or more measurements. The mean URP value fell from 75.0 to 54.0 cm/H2O (p = 0.0003) after the spinal was inserted. There was a non-significant fall in mean cough pressure from 85.0 to 67.5 cm/H2O (p = 0.06). The degree of leakage increased (p = 0.005). Spinal anaesthesia causes a fall in the resistance in the urethra but does not cause a significant fall in the pressure generated by a cough. Women are more likely to leak after coughing during the TVT operation under spinal anaesthesia than they are before the spinal is inserted. The cough test under spinal anaesthesia does not mimic the result of coughing without a spinal.

Quantification of healthy follicles in the neonatal and adult mouse ovary: evidence for maintenance of primordial follicle supply.

Proliferation and partial meiotic maturation of germ cells in fetal ovaries is believed to establish a finite, non-renewable pool of primordial follicles at birth. The supply of primordial follicles in postnatal life should be depleted during folliculogenesis, either undergoing atresia or surviving to ovulation. Recent studies of mouse ovaries propose that intra- and extraovarian germline stem cells replenish oocytes and form new primordial follicles. We quantified all healthy follicles in C57BL/6 mouse ovaries from day 1 to 200 using unbiased stereological methods, immunolabelling of oocyte meiosis (germ cell nuclear antigen (GCNA)) and ovarian cell proliferation (proliferating cell nuclear antigen (PCNA)) and electronmicroscopy. Day 1 ovaries contained 7924+/-1564 (s.e.m.) oocytes or primordial follicles, declining on day 7 to 1987+/-203, with 200-800 oocytes ejected from individual ovaries on that day and day 12. Discarded oocytes and those subjacent to the surface epithelium were GCNA-positive indicating their incomplete meiotic maturation. From day 7 to 100 mean numbers of primordial follicles per ovary were not significantly depleted but declined at 200 days to 254+/-71. Mean numbers of all healthy follicles per ovary were not significantly different from day 7 to 100 (range 2332+/-349-3007+/-322). Primordial follicle oocytes were PCNA-negative. Occasional unidentified cells were PCNA-positive with mitotic figures observed in the cortex of day 1 and 12 ovaries. Although we found no evidence for ovarian germline stem cells, our data support the hypothesis of postnatal follicle renewal in postnatal and adult ovaries of C57BL/6 mice.

Theoretical and finite-element investigation of the mechanical response of spinodal structures.

In recent years there have been major advances in our understanding of the mechanisms of phase separation in polymer and copolymer blends, to the extent that good control of phase-separated morphology is a real possibility. Many groups are studying the computational simulation of polymer phase separation. In the light of this, we are exploring methods which will give insight into the mechanical response of multiphase polymers. We present preliminary results from a process which allows the production of a two-dimensional finite-element mesh from the contouring of simulated composition data. We examine the stretching of two-phase structures obtained from a simulation of linear Cahn-Hilliard spinodal phase separation. In the simulations, we assume one phase to be hard, and the other soft, such that the shear modulus ratio G is large (>or= 10(3)). We indicate the effect of varying composition on the material modulus and on the distribution of strains through the stretched material. We also examine in some detail the symmetric structures obtained at 50% composition, in which both phases are at a percolation threshold. Inspired by simulation results for the deformation of these structures, we construct a "scaling" theory, which reproduces the main features of the deformation. Of particular interest is the emergence of a lengthscale, below which the deformation is non-affine. This length is proportional to G(1/4), and hence is still quite small for all reasonable values of this ratio. The same theory predicts that the effective composite modulus scales also as G(1/4), , which is supported by the simulations.

The effects of gonadotropin-releasing hormone immunization and recombinant follicle-stimulating hormone on the Leydig cell and macrophage populations of the adult rat testis.

The objective of this study was to investigate the role of the gonadotropins and, in particular follicle-stimulating hormone (FSH) in maintaining the Leydig cell and macrophage populations of the adult rat testis. Adult male Sprague-Dawley rats received a gonadotropin-releasing hormone (GnRH) immunogen for a period of 12 weeks in order to induce a selective deficiency in luteinizing hormone (LH) and FSH. Recombinant human FSH was then administered for 7, 14 and 21 days and macrophages and Leydig cells per testis quantified using the "optical disector" method. After GnRH immunization, Leydig cell and macrophage numbers were reduced by 18% and 68%, respectively, compared with normal controls, resulting in an increase in the ratio of Leydig cells to macrophages from 4:1 to 9:1. Leydig cells regressed morphologically following GnRH immunization, and macrophage mean nuclear diameter was significantly reduced. Administration of FSH did not restore the numbers of either cell type; however, FSH did increase macrophage nuclear size. Eosinophils and mast cells were also found sparsely scattered throughout the interstitium after GnRH immunization and persisted in the FSH-treated animals. The results of this study indicate that in the adult rat: 1) both Leydig cell and macrophage numbers are reduced in the gonadotropin-deficient testis; 2) FSH has no effect on the number of either cell type in the absence of LH; and 3) testicular macrophage activity, as indicated by nuclear size, is stimulated by FSH, either directly or indirectly.

Effect of chorionic gonadotropin and flutamide on Leydig cell and macrophage populations in the testosterone-estradiol-implanted adult rat.

The objective of this study was to investigate the role of androgens and nonandrogenic Leydig cell products in maintaining Leydig cell and macrophage numbers in the testis of the adult rat. Adult male Sprague-Dawley rats received Silastic implants containing testosterone and estradiol (T-E) in order to suppress endogenous luteinizing hormone (LH) for 9 weeks. After T-E treatment, Leydig cell and macrophage numbers, quantified using the optical disector approach, were reduced by 40 and 60%, respectively, compared with controls. Administration of human chorionic gonadotropin (hCG) for a period of 10 days restored Leydig cell numbers to control levels, and macrophage numbers were partially restored. Administration of the antiandrogen, flutamide, in combination with hCG treatment in T-E implanted animals prevented the restoration of Leydig cell numbers but did not prevent the recovery of macrophage numbers. In the T-E-implanted animals, there was a decrease in testicular macrophage nuclear size, which was not restored by either hCG or hCG plus flutamide treatment. The results of this study support the hypothesis that LH is the main pituitary regulator of both Leydig cell and macrophage number in the adult rat testis and further indicate that androgens are responsible for maintaining Leydig cell numbers and/or differentiation, but nonandrogenic Leydig cell factors are primarily responsible for controlling macrophage numbers. Testicular macrophage function, as indicated by nuclear size, does not appear to be influenced by LH or testosterone in the adult rat.

Composition and structure of the martian atmosphere: preliminary results from viking 1.

Results from the aeroshell-mounted neutral mass spectrometer on Viking I indicate that the upper atmosphere of Mars is composed mainly of CO(2) with trace quantities of N(2), Ar, O, O(2), and CO. The mixing ratios by volume relative to CO(2) for N(2), Ar, and O(2) are about 0.06, 0.015, and 0.003, respectively, at an altitude near 135 kilometers. Molecular oxygen (O(2)(+)) is a major component of the ionosphere according to results from the retarding potential analyzer. The atmosphere between 140 and 200 kilometers has an average temperature of about 180 degrees +/- 20 degrees K. Atmospheric pressure at the landing site for Viking 1 was 7.3 millibars at an air temperature of 241 degrees K. The descent data are consistent with the view that CO(2) should be the major constituent of the lower martian atmosphere.