Deviant peri-oestrual hormone patterns affect the epithelium of the uterine tube in repeat-breeder heifers

Histopatology of the reproductive tract of Nellore pubertal heifers with genital ureaplasmosis

In order to study and characterize the lesions in the reproductive tract of Nellore heifers naturally infected with Ureaplasma diversum and presenting granular vulvovaginitis syndrome (GVS), fragments of uterine tube, uterus, cervix, vagina and vulva of 20 animals were evaluated. The macroscopic lesions of the vulvovaginal mucosa were classified in scores of "1" mild, until "4", severe inflammation and pustular or necrotic lesions. The histopathological evaluation was performed using scores of "1" to "4", according to the inflammatory alterations. The fragments with severe microscopic lesions (3 and 4) were from the uterine tubes and uterus, which showed leukocytes infiltration and destruction and/or necrosis of epithelium. Alterations in the lower reproductive tract fragments were mild, but characteristics of acute inflammatory processes. The histopathological findings of the reproductive tract of females naturally infected with Ureaplasma diversum are consistent with injuries that compromise the environment from the local where spermatozoa acquires ability to fertilize an oocyte until those where the oocyte is fertilized. Therefore, animals with GVS should be identified early in the herd, because, besides the reduction in the fertility rates caused by tissue damages, they can contribute to disseminate the microorganism. Key words: bovine, tissue evaluation, reproduction, Ureaplasma diversum.

Cellular expression and localization of estrogen receptor α and progesterone receptor mRNA in the bovine oviduct combining laser-assisted microdissection, quantitative PCR, and in situ hybridization

The importance of using techniques that allow the study of pure populations of cells has been increasingly recognized. The authors used laser-assisted microdissection (LAM) in combination with quantitative real-time PCR (qPCR) to assess the relative expression of mRNAs encoding estrogen receptor α (ERα) and progesterone receptor (PR) in the different compartments of the bovine oviduct (epithelium, stroma, smooth muscle coat) during the follicular and mid-luteal phases of the estrus cycle. The localization of receptor mRNA was further studied using non-radioactive in situ hybridization (NISH). A special focus was on whether formalin fixation and paraffin embedding influence the quality and quantity of mRNA obtained from microdissected material. Distinct cyclic changes of the mRNA in the bovine oviduct were observed with elevated levels of PR mRNA transcripts in the epithelium and smooth muscle coat during the follicular phase. The expression of PR mRNA did not vary significantly in the stroma of the bovine oviduct during follicular and mid-luteal phases. In conclusion, the authors found that LAM with qPCR can precisely locate and accurately quantify mRNA expression in specific cell populations from formalin-fixed and paraffin-embedded oviductal tissue.

Pregnancy rates in repeat-breeder heifers following multiple artificial inseminations during spontaneous oestrus

Hormonal asynchronies during oestrus, related to the presence of suprabasal plasma-progesterone (P4) concentrations and a delayed ovulation, interfere with the fertility of repeat-breeder heifers (RBH). Since tubal dysfunction can occur in connection with hormonal asynchronies and constrained availability of fertile spermatozoa at the time of ovulation, the present study tested the hypothesis that frequent sperm deposition from onset of oestrus to ovulation may improve pregnancy rates in RBH. Five RBH and five virgin heifers (VH; controls) were repeatedly artificially inseminated (AI) at 6 h intervals from onset of oestrus to spontaneous ovulation. Hormone analyses revealed suprabasal P₄ concentrations and a delay in the occurrence of the luteinising hormone (LH) surge, but a normal cortisol profile in RBH. Compared with controls, RBH presented longer interval from onset of oestrus to ovulation, and therefore, received more AIs. Pregnancy rates in RBH reached control levels (60%; NS), indicating that the hypothesis might be correct. Pregnancy rates in VH were below the expected range, presumably attributed to a deleterious influence of the frequent handling. The study suggests that pregnancy rates can be improved in RBH by frequent AI in relation to spontaneous ovulation. However, this practice of repeated manipulations, while seeming not to show adverse effects, lacks practicality for routine use.

Oocyte competence in repeat-breeder heifers: effects of an optimized ovum pick-up schedule on expression of oestrus, follicular development and fertility

Repeat-breeder heifers (RBH) have been shown to present reproductive perturbations during spontaneous cyclicity, which affects oestrus and ovulation. Some of these disturbances (e.g. deviating hormone patterns) are also present during and after cycles of twice-weekly ovum pick-up (o.p.u.), performed according to an optimized schedule allowing normal oestrous cyclicity. In the present study, the effects of o.p.u. on oocyte competence in in vitro maturation (i.v.m.) and in vitro fertilization (i.v.f.) have been evaluated, as were the effects on expression of oestrus and fertility in five RBH (> or =4 artificial inseminations) and five virgin heifers (VH controls). In total, 269 RBH and 174 VH oocytes were scored for quality prior to i.v.m. and i.v.f. The number of follicles available for puncture was higher in RBH, but the oocyte recovery rate after o.p.u. was lower in RBH compared with VH controls and the recovered RBH oocytes were of lower quality, as judged by their appearance at retrieval. Confocal laser scanning and transmission electron microscopy of immature oocytes did not reveal any differences between RBH and VH control oocytes with respect to nuclear and mitochondrial status. However, after i.v.m., the cytoplasmic spatial reorganization of mitochondria and cortical granules was less advanced in RBH, which could contribute to the subfertility that defines the syndrome. Cleavage rates after i.v.f. were similar in RBH and VH controls. Subsequent to the o.p.u. period, in vivo fertility after controlled artificial insemination was comparable with field fertility rates in both RBH and VH.