Journal of reproduction and fertility最新文献

As an integral part of the development of an artificial insemination programme in the captive koala, female reproductive physiology and behaviour were studied. The oestrous cycle in non-mated and mated koalas was characterized by means of behavioural oestrus, morphology of external genitalia and changes in the peripheral plasma concentrations of oestradiol and progestogen. The mean (+/- SEM) duration of the non-mated oestrous cycle and duration of oestrus in 12 koalas was 32.9 +/- 1.1 (n = 22) and 10.3 +/- 0.9 (n = 24) days, respectively. Although the commencement of oestrous behaviour was associated with increasing or high concentrations of oestradiol, there were no consistent changes in the morphology or appearance of the clitoris, pericloacal region, pouch or mammary teats that could be used to characterize the non-mated cycle. As progestogen concentrations remained at basal values throughout the interoestrous period, non-mated cycles were considered non-luteal and presumed anovulatory. After mating of the 12 koalas, six females gave birth with a mean (+/- SEM) gestation of 34.8 +/- 0.3 days, whereas the remaining six non-parturient females returned to oestrus 49.5 +/- 1. 0 days later. After mating, oestrous behaviour ceased and the progestogen profile showed a significant increase in both pregnant and non-parturient females, indicating that a luteal phase had been induced by the physical act of mating. Progestogen concentrations throughout the luteal phase of the pregnant females were significantly higher than those of non-parturient females. Parturition was associated with a decreasing concentration of progestogen, which was increased above that of basal concentrations until 7 days post partum.

The epithelium of the human oviduct expresses the major histocompatibility complex (MHC) class II and shows endocytic properties towards luminal antigens. Therefore, the epithelial cells might behave as antigen-presenting cells, inducing a local immune response. The activation of antigen-specific T cells not only requires presentation of the peptide antigen by MHC class II, but also the presence of co-stimulatory molecules in the antigen-presenting cells. Therefore, the expression of the intercellular adhesion molecule 1 (ICAM-1) was examined in the epithelium of the human oviduct. Most oviducts showed epithelial ICAM-1 expression, as assessed by immunocytochemistry, western blot analysis and RT-PCR assay, and the expression was restricted to the luminal border of ciliated and secretory cells. Interferon gamma, interleukin 1 and lipopolysaccharide treatments increased the percentage of ICAM-1-positive cells in primary cultures, indicating that the expression of ICAM-1 in the oviduct might be upregulated in vivo by inflammatory cytokines or bacterial infections. Binding assays between allogenic phytohaemagglutinin-activated lymphocytes and epithelial monolayers expressing ICAM-1 demonstrated that this molecule stimulated lymphocyte adherence. The presence of ICAM-1, in addition to MHC class II, supports the putative role of the oviductal epithelium in antigen presentation. The exclusive apical distribution of ICAM-1 indicates that T-cell activation would occur in a polarized manner. Binding of lymphoid cells to the surface of the oviductal epithelium may help to retain these immune cells that are required for the clearance of pathogens.

The pulsatile secretion pattern of growth hormone was investigated during four stages of the luteal phase and during mid-anoestrus in six cyclic beagle bitches. Plasma samples were obtained via jugular venepuncture at 10 min intervals for 12 h at 19 +/- 2 (mean +/- SEM; luteal phase 1), 38 +/- 2 (luteal phase 2), 57 +/- 2 (luteal phase 3), 78 +/- 2 (luteal phase 4) and 142 +/- 4 days (mid-anoestrus) after ovulation. During all stages, growth hormone was secreted in a pulsatile fashion. The mean basal plasma growth hormone concentration during luteal phase 1 (2.2 +/- 0.3 microgram l(-1)) was significantly higher than that during luteal phase 4 (1.5 +/- 0.1 microgram l(-1)) and mid-anoestrus (1.4 +/- 0.2 microgram l(-1)). The mean area under the curve (AUC) above zero during luteal phase 1 (27.3 +/- 2.7 microgram l(-1) in 12 h) tended to be higher than that during luteal phase 4 (20.8 +/- 1.8 microgram l(-1) in 12 h) and mid-anoestrus (19.2 +/- 2.5 microgram l(-1) in 12 h). In contrast, the mean AUCs above the baseline during luteal phase 1 (1.1 +/- 0.5 microgram l(-1) in 12 h) and luteal phase 2 (1.2 +/- 0.5 microgram l(-1) in 12 h) were significantly lower than that during luteal phase 4 (2.8 +/- 0.5 microgram l(-1) in 12 h). In conclusion, the pulsatile secretion pattern of growth hormone changes during the luteal phase in healthy cyclic bitches: basal growth hormone secretion is higher and less growth hormone is secreted in pulses during stages in which the plasma progesterone concentration is high. It is hypothesized that this change is caused by a partial suppression of pituitary growth hormone release by progesterone-induced growth hormone production in the mammary gland. The progesterone-induced production of growth hormone in the mammary gland may promote the physiological proliferation and differentiation of mammary gland tissue during the luteal phase of the bitch by local autocrine-paracrine effects. In addition, progesterone-induced mammary growth hormone production may exert endocrine effects, such as hyperplastic changes in the uterine epithelium and insulin resistance.

The major obstacle in the extensive analysis of the embryonic genome is the small number of cells typically obtained after the embryo biopsy. The object of the present study was to develop a simple approach that would allow the collection of a sufficient number of cells from a single embryo for use in further analyses. A micromanipulator was used to make a hole in the zona pellucida of 28 compacted morulae, 27 early blastocysts and 31 expanded blastocysts. After further culture, the trophoblastic cells, which herniated through this hole, were cut and cultured in vitro for different periods and used for embryo sexing. The results showed that biopsies can be taken successfully from 96.3% of early blastocysts, compared with 67.7% of expanded blastocysts and 71.4% of compacted morulae. The trophoblastic vesicles contained 20.8 +/- 6.7 cells (mean +/- SEM) and, when cultured, formed a confluent monolayer. The sex of cells cultured was assayed by PCR and the 12 lambs born after transfer of biopsied embryos confirmed its 100% accuracy. Moreover, no significant differences were found in the viability rates in vitro among blastocysts vitrified immediately after biopsy (77.8%), blastocysts biopsied and vitrified after 24 h culture (76.9%) and blastocysts vitrified without manipulation (88.5%). In experiments in vivo, the lambing rate of biopsied and vitrified blastocysts was significantly (P < 0.05) lower (40.0%) compared with vitrified control embryos (68.7%). This new approach to the biopsy of preimplantation embryos is a useful good model in the assisted reproductive technologies of domestic, wild and human species.

Studies have shown inhibitory effects of endogenous opioids on LH secretion in early post-natal heifers. However, it is not clear whether these effects change during the rest of the prepubertal period or whether the inhibitory influences on the GnRH neurones are direct or by way of other neuronal systems. Two experiments were performed in heifer calves to study the developmental patterns of opioidergic, dopaminergic and adrenergic regulation of LH and the possible interactions between opioids and dopaminergic and adrenergic neuronal systems, in the regulation of LH secretion. In Expt 1 four groups each of five heifer calves were used. Blood samples were taken every 15 min for 10 h and each calf received one of the following treatments as a single injection at 4, 14, 24, 36 and 48 weeks of age: (i) naloxone (opioid antagonist, 1 mg kg(-1), i. v.); (ii) sulpiride (dopamine D2 antagonist, 0.59 mg kg(-1), s.c.); (iii) naloxone and sulpiride combined; or (iv) vehicle (control group). Treatments began after the first blood sample was taken. The design of Expt 2 was similar; a separate group of heifer calves was assigned to receive one of the following treatments as a single injection at 4, 14, 24, 36 and 48 weeks of age: (i) naloxone; (ii) phenoxybenzamine (an alpha-adrenoreceptor blocker, 0.8 mg kg(-1), i. v.); (iii) naloxone and phenoxybenzamine; (iv) or vehicle. Results from Expt 1 showed that the maximum concentration of LH and the number of calves responding to treatments with an LH pulse was higher in the first hour after treatments at 36 and 48 weeks of age in the naloxone group compared with the control or sulpiride groups (P < 0.05). These values in the naloxone group also increased over time and were greatest at 48 weeks of age (P < 0.05). In heifers given naloxone + sulpiride treatment at 36 and 48 weeks of age, maximum concentrations of LH in the first hour after treatment did not differ from the naloxone and control groups. In Expt 2, at 36 and 48 weeks of age, treatment with naloxone with or without phenoxybenzamine resulted in higher concentrations of LH than in the controls (P < 0.05). No pulses were seen over the first hour of treatment at 36 and 48 weeks of age in heifers treated with phenoxybenzamine. The 10 h periods of blood sampling at 48 weeks of age revealed that phenoxybenzamine alone suppressed LH pulse frequency and mean serum concentrations of LH compared with the control group (P < 0.05). It was concluded that a strong or more acute inhibition of LH secretion by endogenous opioids developed in mid- to late prepubertal heifers, or alternatively, that removal of opioidergic inhibition at the GnRH neurone unmasked stimulatory inputs that were greater in heifers close to first ovulation. Since sulpiride appeared to negate in part the effects of naloxone on LH release, the suppressive effects of opioids could be exerted in part through the inhibition or blocking of a stimulatory dopaminergic system. alpha-Adrenergic neuron

In vitro release and content of GnRH in mediobasal hypothalamic slices are reduced by ovariectomy of female ferrets but are not affected by castration of male ferrets in breeding condition. The aim of the present study was to determine whether this sex difference reflects a sexually dimorphic effect of gonadal steroids on mediobasal hypothalamic GnRH mRNA content of male and female ferrets killed 4 weeks after gonadectomy, either with or without steroid hormone replacement. This time interval exceeds the 6-10 days needed for increments in plasma LH concentrations to stabilize after gonadectomy of ferrets of both sexes. In situ hybridization using an (35)S-labelled oligoprobe complementary to the human GnRH coding region showed that the number of mediobasal hypothalamic neurones and the cellular content of GnRH mRNA did not differ significantly among groups of male and female ferrets that were either in breeding condition or that had been gonadectomized and treated with sex steroids or oil vehicle. These results indicate that gonadal hormones regulate mediobasal hypothalamic GnRH biosynthesis and release in both sexes via post-transcriptional events that may include GnRH mRNA translation or the conversion of pre-pro GnRH precursor into mature GnRH.