Physiological aspects of androstenone and skatole formation in the boar-A review with experimental data.

The understanding of estrogen's function in the male reproductive tract is limited, and estrogen receptor (ER) localization in the reproductive tract of the adult male rat has not been described. In the present study, ERalpha was localized by immunohistochemistry using ER21 antibody, which recognizes only ERalpha. Strongest immunoreactivity was seen in epithelia of ductuli efferentes and the initial segment of the epididymis. Nuclei of both ciliated and nonciliated cells were positive. The epithelium of the rete testis, and caput, corpus, and cauda epididymides stained less intensely for ERalpha. The vas deferens epithelium was ERalpha-negative. Stromal tissue in the excurrent ducts was also ERalpha-positive. Using 3H-estradiol autoradiography, specific binding of estradiol was seen in nuclei of ductuli efferentes. Estrogen receptor alpha mRNA expression was greatly enhanced in ductuli efferentes compared to other regions of the male tract and was 3.5x greater than in the uterus. For comparison, the presence of ERalpha was determined using reverse transcription-polymerase chain reaction (RT-PCR) amplification. Estrogen receptor beta mRNA was expressed throughout the male tract and in the prostate. These results indicate that all organs in the male excurrent ductal system of the rat express ERalpha and are potential targets of estrogen. However, the ductuli efferentes are the site of the most intense ERalpha expression. The role of ERbeta remains to be determined, but its expression appears ubiguitous in the male tract.

Estrogen Receptor (α and β) Expression in the Excurrent Ducts of the Adult Male Rat Reproductive Tract

In pigs, uterine exposure to the constituents of semen is known to increase litter size but the underlying physiological mechanisms remain undefined. Studies in rodents and humans implicate immune modulating moieties in seminal plasma as likely candidates, acting through enhancing the receptivity of the female tract. In this study, the acute and longer term effects of seminal plasma on cytokine expression and leukocyte abundance in the pig endometrium during early pregnancy have been characterised. The reproductive tracts of gonadotrophin-primed pre-pubertal gilts treated with intrauterine infusions of either pooled seminal plasma or phosphate-buffered saline (PBS) were retrieved at 34 h, or on day 5 and day 9 after treatment. Seminal plasma elicited an endometrial inflammatory infiltrate comprised of predominantly macrophages and major histocompatibility complex class II+-activated macrophages and dendritic cells. The abundance of these cells was greatest at the pre-ovulatory (34 h) time-point and their increase relative to PBS-treated tissues was maintained until day 9 after seminal plasma treatment. Seminal plasma induced the expression of the cytokines, granulocyte macrophage colony-stimulating factor, interleukin-6 and monocyte chemoattractant protein-1, and the eicosanoid-synthesising enzyme cyclo-oxygenase-2. Expression was maximal 34 h after treatment but altered expression patterns as a consequence of seminal plasma induction persisted through early pregnancy. These changes were accompanied by altered dynamics in pre-implantation embryo development with an increase in the number of embryos and in their viability after seminal plasma treatment. Together, these findings implicate factors in seminal plasma in programming the trajectory of uterine cytokine expression and leukocyte trafficking during early pregnancy and in regulating pre-implantation embryo development in the pig.

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Seminal plasma regulates endometrial cytokine expression, leukocyte recruitment and embryo development in the pig

This review focuses on the importance of oestrogen and oestrogen receptors in the male reproductive system, with a special interest in the newly discovered role of oestrogen in the regulation of fluid reabsorption in the efferent ductules of the testis. Early work on oestrogen synthesis indicated that Leydig and Sertoli cells were the only important cells in the production of this steroid in the adult testis. However, more recent work has shown that germ cells and spermatozoa also contain aromatase and produce oestrogen. The observation that germ cells synthesize oestrogen contributed to a new hypothesis that oestrogen in the lumen of the male reproductive tract targets the epithelial lining of efferent ductules and the epididymis. The location of nuclear oestrogen receptors in the male reproductive tract has also been investigated and it has been found that oestrogen receptor α is more abundant in the efferent ductules of the testis than in any other tissue of the male or female. In all species examined to date, oestrogen receptor α has been found to be abundant in the efferent ductules. The structure and function of the efferent ductules are taken into account as these tubules are responsible for the reabsorption of almost 90% of the luminal rete testis fluid. Thus, it was logical to hypothesize that oestrogen receptors play a role in the regulation of fluid reabsorption in efferent ductules. The oestrogen receptor α knockout mouse was used to help define this role of the receptor in males. In this animal model, the efferent ductules are altered markedly from a reabsorptive epithelium to a squamous epithelium devoid of lysosomes and endocytotic organelles. Although the separate roles for oestrogens and androgens in the regulation of fluid reabsorption are controversial and remain to be resolved, it is now established that loss of oestrogen receptor function in males interferes with the resorptive function of efferent ductules, a function that is essential for fertility. Future studies will focus on the biochemical and physiological mechanisms involved in the regulation of water and ion movement by oestrogen in the male reproductive tract.

Oestrogen in fluid transport in efferent ducts of the male reproductive tract

http://directory.umm.ac.id/Data%20Elmu/jurnal/A/Animal%20Reproduction%20Science/Vol64.Issue1-2.Dec2000/2065.pdf

Effects of season and breed on sperm acrosin activity and semen quality of boars.

Seminal oestrogens in the boar: origin and functions in the sow.

Seasonal effect on steroids in blood plasma and seminal plasma of boars

Photoperiodic influences on reproduction of domestic boars. I. Light influences on testicular steroids in peripheral blood plasma and seminal plasma.

Summary

Fifteen unmated Landrace sows with indwelling jugular vein catheters were used to monitor ovarian function by profiles of progesterone and 17β-oestradiol (Oe2) throughout the year. A biphasic pattern of acyclia was found. Prolonged periods of low progesterone and Oe2-concentrations occurred in two sows in February/March and in six sows in July until November. Seven of the 15 sows revealed acyclia at least once during the investigation. The progesterone concentrations during the luteal phases of cyclic animals were significantly lower in August than in November and January. These findings indicate similarities to the seasonal dependency of ovarian function which is well known in the wild pig.



In cyclic sows, oestrous behaviour tended to be less pronounced in summer. Oe2 concentrations in August were also significantly lower than concentrations before ovulations between November and January.



Zusammenfassung

Nachweis saisonaler Schwankungen der Ovarfunktion bei ungedeckten Sauen durch Messung von Progesteron und 17bT-Oestradiol im Blutplasma



Von 15 maturen, nicht gedeckten Sauen (DL) wurden uber Jugularisdauerkatheter fur 4–14 Monate Blutproben gewonnen und Progesteron und Oestradiol-17β gemessen. Azyklie wurde aufgrund der Hormonprofile in zwei Zeitabschnitten nachgewiesen: Phasen mit konstant niedrigen Konzentrationen von Progesteron und Oestradiol-17β traten bei 2 Sauen im Februar/Marz und bei 6 Sauen zwischen Juli und November auf. Insgesamt zeigten 7 der 15 Sauen azyklische Phasen.



Bei den Sauen, die auch im Sommer zyklisch waren, wurden jedoch signifikant niedrigere Progesteronmaxima nach Ovulationen im August, verglichen mit Ovulationen im November und Januar, gemessen. Zudem waren die Maximalkonzentrationen von Oestradiol-17β vor Ovulationen im August ebenfalls signifikant niedriger als vor Ovulationen im November, Dezember und Januar. Oestrussymptome waren im Sommer weniger deutlich ausgepragt als in den ubrigen Jahreszeiten.



Diese saisonalen Unterschiede im Zyklusgeschehen des Hausschweines zeigen somit Parallelen zur streng saisonalen Abhangigkeit des Reproduktionsgeschehens des Wildschweines.

Seasonal variation of the ovarian function in unmated sows revealed by the measurement of progesterone and 17 beta-oestradiol in peripheral bloodplasma.

D. Schopper

Papers

Seminal oestrogens in the boar: origin and functions in the sow.

Seasonal effect on steroids in blood plasma and seminal plasma of boars

Photoperiodic influences on reproduction of domestic boars. I. Light influences on testicular steroids in peripheral blood plasma and seminal plasma.

Seasonal variation of the ovarian function in unmated sows revealed by the measurement of progesterone and 17 beta-oestradiol in peripheral bloodplasma.