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  • Author: J. A. THOMAS x
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Prostate gland fructose was measured enzymatically in normal and castrate mice. Regardless of protein precipitation procedure, castration resulted in a loss of prostatic fructose.

Prostate gland fructose levels were higher, using the resorcinol method, only when tricholoroacetic acid (TCA) was used to precipitate tissue proteins. Similar procedures employing supernatants obtained from barium hydroxide-zinc sulphate precipitated organs were comparable to enzymatically measured fructose.

The use of radio-active fructose and fructose-1,6-diphosphate established that heavy metal precipitation resulted in over 90% of the labelled fructose residing in the supernatant and a similar amount of phosphate ester found in the precipitate. The use of TCA to precipitate prostate gland proteins revealed that both fructose and fructose-1,6-diphosphate were predominantly found in the supernatant (93 and 95% respectively). Very little radio-activity was found in the precipitate fraction, indicating that TCA was unable to separate free hexose adequately from phosphate esters.

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A. D. Cookson, A. N. Thomas and J. A. Foulkes

Summary. Antiserum was raised in rabbits against an egg-yolk lipoprotein fraction previously shown to have cryoprotective properties. It was used in conjunction with alkaline phosphatase-conjugated goat anti-rabbit IgG to demonstrate lipoprotein interaction with bovine spermatozoa. The lipoprotein bound firmly to spermatozoa and was not removed by extensive washing, suggesting that the lipoprotein had become irreversibly associated with the sperm membranes.

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S. P. Brinsko, B. A. Ball, P. G. Miller, P. G. A. Thomas and J. E. Ellington

This study was designed to investigate the development of day 2 embryos obtained from young and aged mares, co-cultured with oviductal epithelial cells obtained from mares in each age group in a 2 × 2 crossover design. Young, fertile mares (n = 19; 2–7 years of age) and aged, subfertile, mares (n = 16; 17–24 years of age) were used as embryo and oviductal epithelial cell donors. Embryos (n = 37) were collected from the oviducts 2 days after ovulation and were paired (embryos obtained from young mares with embryos obtained from aged mares) so that eight pairs were co-cultured with young mare oviductal epithelial cells and eight pairs were co-cultured with aged mare oviductal epithelial cells. Five additional embryos obtained from young mares were co-cultured with oviductal epithelial cells from either young mares or aged mares but were not paired. Embryos were co-cultured for 7 days at 38.5°C in 5% CO2 or until morphological degeneration was detected. The proportions of paired embryos that reached the blastocyst stage were similar for embryos obtained from young mares and embryos obtained from aged mares after co-culture with oviductal epithelial cells from young mares (6 of 8 versus 5 of 8) or from aged mares (6 of 8 versus 5 of 8), respectively. Although the overall rate of development of embryos to blastocyst from both young mares and aged mares was similar, blastocysts developing from embryos obtained from aged mares were inferior to blastocysts obtained from young mares in terms of number of cell nuclei, quality score, and diameter at day 7. The results of this experiment indicate that the high rate of early embryonic loss in aged, subfertile mares may be due to inherent developmental defects in their embryos, but does not appear related to the ability of embryos from aged, subfertile mares to reach the blastocyst stage.

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Jonathan W Boyd, Thomas J Lechuga, Charlotte A Ebner, Michael A Kirby and Steven M Yellon

The hypogastric nerve is a major pathway innervating the uterine cervix, yet its contribution to the processes of cervical ripening and parturition is not known. The main objective of this study was to determine the effect of hypogastric nerve transection on remodeling of the cervix and timing of birth. As an initial goal, processes associated with remodeling of the peripartum cervix were studied. The cervix was obtained from time-dated pregnant rats on days 15, 19, 21, and 21.5 of pregnancy, and post partum on the day of birth (day 22). The cervix was excised, post-fixed overnight, and sections stained to evaluate collagen content and structure or processed by immunohistochemistry to identify macrophages or nerve fibers. The census of macrophages and density of nerve fibers in the cervix peaked on day 21, the day before birth, and then declined post partum. These results replicate in time course and magnitude previous studies in mice. To address the main objective, the hypogastric nerve was bilaterally transected on day 15 post-breeding; sham-operated rats served as controls. Pups were born in both groups at normal term. Transection of the hypogastric nerves did not affect remodeling of collagen or the census of macrophages or the density of nerve fibers in the cervix. These findings support the contention that enhanced innervation and immigration of immune cells are associated with remodeling of the cervix and parturition, but that a neural pathway other than the hypogastric nerve may participate in the process of cervical ripening.

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Steven M Yellon, Lauren A Grisham, Genevieve M Rambau, Thomas J Lechuga and Michael A Kirby

The transneuronal tracer pseudorabies virus was used to test the hypothesis that connections from the cervix to the forebrain and hypothalamus are maintained with pregnancy. The virus was injected into the cervix of nonpregnant or pregnant mice, and, after 5 days, virus-labeled cells and fibers were found in specific forebrain regions and, most prominently, in portions of the hypothalamic paraventricular nucleus. With pregnancy, fewer neurons and fibers were evident in most brain regions compared to that in nonpregnant mice. In particular, little or no virus was found in the medial and ventral parvocellular subdivisions, anteroventral periventricular nucleus, or motor cortex in pregnant mice. By contrast, labeling of virus was sustained in the dorsal hypothalamus and suprachiasmatic nucleus in all groups. Based upon image analysis of digitized photomicrographs, the area with label in the rostral and medial parvocellular paraventricular nucleus and magnocellular subdivisions was significantly reduced in mice whose cervix was injected with virus during pregnancy than in nonpregnant mice. The findings indicate that connections from the cervix to brain regions that are involved in sensory input and integrative autonomic functions are reduced during pregnancy. The findings raise the possibility that remaining pathways from the cervix to the forebrain and hypothalamus may be important for control of pituitary neuroendocrine secretion, as well as for effector functions in the cervix as pregnancy nears term.

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A. Stamouli, M. J. B. O'Sullivan, S. Frankel, E. J. Thomas and M. C. Richardson

Granulosa cells were isolated from follicular aspirates collected at ovum recovery for in vitro fertilization. Cells were cultured in a defined medium on artificial extracellular matrix (Matrigel) in the presence or absence of hCG as a model for corpus luteum function. Release of cells from this culture system is reduced by hCG and this effect may be mediated through an inhibition of extracellular matrix degradation. Using zymography and western blot analysis, we confirm the identity of matrix metalloproteinases-2 and -9 in culture media. Matrix metalloproteinase-9 was the predominant gelatinase in freshly prepared granulosa cells and in culture media, and also represented a major metalloproteinase component in homogenates of early and mid-luteal phase samples of corpora lutea. Quantitative analysis of matrix metalloproteinases in culture media, obtained throughout the 14 day culture period and expressed per μg of DNA, showed that matrix metalloproteinase-2, undetectable on day 2, rose throughout the culture period and that this rise was significantly inhibited by hCG. In contrast, matrix metalloproteinase-9 was clearly detectable on day 2 and remained relatively constant throughout much of the culture (day 2 to day 12) in the presence of gonadotrophin. Significantly increased production of matrix metalloproteinase-9 (day 6 to day 12) was evident in the absence of hCG. Our results provide further evidence for the hypothesis that the rescue of the corpus luteum in early pregnancy involves the maintenance of cellular function through the stabilization of the extracellular matrix.

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Alexis D Greene, Stephanie A Lang, Jessica A Kendziorski, Julie M Sroga-Rios, Thomas J Herzog and Katherine A Burns

Endometriosis currently affects ~5.5 million reproductive-aged women in the U.S. with symptoms such as painful periods (dysmenorrhea), chronic pelvic pain, pain with intercourse (dyspareunia), and infertility. It is defined as the presence of endometrial tissue outside the uterine cavity and is found predominately attached to sites within the peritoneal cavity. Diagnosis for endometriosis is solely made through surgery as no consistent biomarkers for disease diagnosis exist. There is no cure for endometriosis and treatments only target symptoms and not the underlying mechanism(s) of disease. The nature of individual predisposing factors or inherent defects in the endometrium, immune system, and/or peritoneal cavity of women with endometriosis remains unclear. The literature over the last 5 years (2010–2015) has advanced our critical knowledge related to hormones, hormone receptors, immune dysregulation, hormonal treatments, and the transformation of endometriosis to ovarian cancer. In this review, we cover the aforementioned topics with the goal of providing the reader an overview and related references for further study to highlight the progress made in endometriosis research, while concluding with critical areas of endometriosis research that are urgently needed.

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Jessica A McCoy, Benjamin B Parrott, Thomas R Rainwater, Phillip M Wilkinson and Louis J Guillette Jr

Despite the widespread occurrence of environmental sex determination (ESD) among vertebrates, our knowledge of the temporal dynamics by which environmental factors act on this process remains limited. In many reptiles, incubation temperature determines sex during a discrete developmental window just prior to and coincident with the differentiation of the gonads. Yet, there is substantial variation in sex ratios among different clutches of eggs incubated at identical temperatures during this period. Here, we test the hypothesis that temperatures experienced prior to the reported thermosensitive period for alligators (Alligator mississippiensis) can impact how the sex determination system responds to thermal cues later in development. Temperature shift experiments on eggs collected from the field within 24 h of oviposition were employed to decouple various maternal influences from thermal effects, and results demonstrate a previously undefined window of thermosensitivity occurring by stage 15 of embryonic development, six stages earlier than previously reported. We also examine the intrasexual expression of several male- and female-biased genes and show that while male-biased genes display no intrasexual differences, ovarian CYP19A1 (aromatase) transcript abundance differs by approximately twofold depending on thermal exposures experienced at early stages of embryonic development. These findings expand our understanding of the ESD in the alligator and provide the rationale for reevaluation of the temporal dynamics of sex determination in other crocodilians.

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N. C. Whitley, M. N. Quirk-Thomas, J. O. Skelton, A. B. Moore, J. Purvis, Y. Qiu and N. M. Cox

Twenty-four crossbred primiparous sows were used to investigate the influence of insulin administration after weaning on the intrafollicular insulin-like growth factor I (IGF-I) system. Sows received 0.4 iu insulin kg−1 bodyweight or an equivalent volume of saline for 3 days (n = 5 insulin; n = 4 saline) or 5 days (n = 5 insulin; n = 6 saline) after weaning or served as untreated controls on day 1 (n = 4). The number and diameters of ovarian follicles were recorded, and fluid was aspirated from the 20 largest follicles for determination of oestradiol and IGF-I by radioimmunoassay and of insulin-like growth factor-binding proteins (IGFBPs) by western ligand blotting. The walls of the follicles were collected for mRNA analysis by RNase protection assay or granulosa cells were collected for estimation of apoptosis by flow cytometry. Insulin treatment resulted in smaller diameters of all follicles (P < 0.05) and tended (P < 0.07) to increase the number of follicles available on day 5 compared with saline-treated animals (19.8 versus 17.8). The concentration of oestradiol in follicular fluid from large (7–10 mm) follicles on days 3 and 5 was reduced (treatment by size class interaction; P < 0.05) by insulin treatment. Insulin also reduced intrafollicular concentrations of IGF-I at days 3 and 5 after weaning (treatment by day interaction; P < 0.02) while the amounts of IGFBP-3 and IGFBPs of molecular mass 30 and 22 kDa decreased from day 3 to day 5 in saline-treated animals only (treatment by day interaction; P < 0.05). Gene expression for IGF-I increased in saline-treated animals but decreased fourfold in insulin-treated sows from day 3 to day 5 (treatment by day interaction; P < 0.002). Gene expression for IGFBP-3 decreased (P < 0.04) from day 3 to day 5, while expression of IGFBP-2 was unaffected by treatment or day. Overall, insulin influenced the IGF-I system in a manner consistent with slowing follicular growth and possibly allowed more follicles to become available for ovulation.

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Constantine A Simintiras, Thomas Fröhlich, Thozhukat Sathyapalan, Georg J Arnold, Susanne E Ulbrich, Henry J Leese and Roger G Sturmey

Oviduct fluid is the microenvironment that supports early reproductive processes including fertilisation, embryo cleavage and genome activation. However, the composition and regulation of this critical environment remain rather poorly defined. This study uses an in vitro preparation of the bovine oviduct epithelium to investigate the formation and composition of in vitro-derived oviduct fluid (ivDOF) within a controlled environment. We confirm the presence of oviduct-specific glycoprotein 1 in ivDOF and show that the amino acid and carbohydrate content resembles that of previously reported in vivo data. In parallel, using a different culture system, a panel of oviduct epithelial solute carrier genes and the corresponding flux of amino acids within ivDOF in response to steroid hormones were investigated. We next incorporated fibroblasts directly beneath the epithelium. This dual culture arrangement represents more faithfully the in vivo environment and impacts on ivDOF composition. Lastly, physiological and pathophysiological endocrine states were modelled and their impact on the in vitro oviduct preparation was evaluated. These experiments help clarify the dynamic function of the oviduct in vitro and suggest a number of future research avenues, such as investigating epithelial–fibroblast interactions, probing the molecular aetiologies of subfertility and optimising embryo culture media.