Births of freemartins derived from embryos reconstructed with ear fibroblasts. (1/19)

Although the combination of artificial insemination (AI) and embryo transfer (ET) is effective for preventing large offspring syndrome in clone cattle production, it may cause freemartinism. In this study, 51 reconstructed embryos were transferred to artificially inseminated recipients. Of those 9 twin pregnancies, three delivered male and female offsprings. The females had tufts of long coarse hair and short blind pouch at the vaginal end. At necropsy, hypoplastic testicles and epididymis, which connected to the uterus through the spermatic cord, were found and seminal vesicles were also noted. All females had mixed sex chromosome configuration (60, XX and 60, XY). These results suggest that the combined ET program can cause freemartinism, which reduces the efficiency of clone cattle production.  (+info)

Inter-relationships among gonadotrophins, reproductive steroids and inhibin in freemartin ewes. (2/19)

Freemartins are sterile XX/XY chimaeras that occur as a result of placental fusion between male and female fetuses during early pregnancy. Freemartins occur predominantly in cattle, although the prevalence of ovine freemartinism is increasing. In this study, the reproductive endocrinology of ovine freemartins was compared with that of normal sheep. Freemartins had significantly (P < 0.001) higher basal concentrations of LH and FSH than did normal ewes or rams, although the response of LH to GnRH (10 microg) was similar in freemartins, ewes and rams. Resting concentrations of oestradiol were similar in freemartins and ewes and were increased in both after eCG administration. Testosterone concentrations were higher in freemartins than in ewes, but were unresponsive to GnRH or eCG. Administration of 62.5 mg progesterone or 25 lg oestradiol twice a day for 3 days suppressed LH concentrations to baseline values in freemartins, ewes and rams. In ewes, 500 microg oestradiol administered twice a day caused preovulatory surges in LH concentrations, but suppressed LH in freemartins to baseline values. Thus, LH secretion can potentially be regulated in freemartins by gonadal steroids. FSH concentrations in freemartins were not suppressed by doses of inhibin that were effective in ewes and rams. Therefore, freemartins behave in part like castrated animals, as they have high basal concentrations of LH and FSH, which can be stimulated by GnRH and suppressed by gonadal steroids. Conversely, inhibin does not suppress FSH concentrations in freemartins, and freemartins have circulating concentrations of steroids intermediate between those of castrated and normal animals.  (+info)

Plasma progesterone, androstenedione and testosterone concentrations in freemartin heifers. (3/19)

Plasma concentrations of testosterone, androstenedione and progesterone in freemartins, and normal cyclic and non-cyclic heifers were studied. The plasma testosterone concentrations were in general less than 10 pg/ml in all animals. The mean androstenedione concentration of 28 pg/ml in 10- to 12-month-old freemartins was significantly lower than the mean of 58 to 60 pg/ml for normal 10- to 12-month-old heifers. At 24 months of age the mean androstenedione concentration in the freemartins had risen significantly to 65 pg/ml.  (+info)

Limited contribution of circulating cells to the development and maintenance of nonhematopoietic bovine tissues. (4/19)

Bone marrow-derived stem cells appear surprisingly multipotent in experimental settings, but the physiological significance of such plasticity is unclear. We have used sex-mismatched cattle twins with stably chimeric hematopoietic systems to investigate the general extent of integration of circulating cells to the nonhematopoietic cell lineages in an unmanipulated large mammal. The donor-derived (Y+) nonhematopoietic cells in female recipient tissues were visualized by Y-chromosome specific in situ hybridization combined with pan-leukocyte labeling. Y+ leukocytes were frequent in all tissues, but in 11 of 12 animals, average contribution to nonhematopoietic lineages was in any tissue below 1% (in brain <0.001%). Significantly higher integration rate was detected in regenerating granulation tissue. Also, one animal showed a high frequency of nonhematopoietic Y+ cells in several tissues, including intestinal epithelium and mammary gland stroma. In conclusion, circulating cells do not appear significant in the development and maintenance of nonhematopoietic bovine tissues, but may be important in regeneration and other special conditions.  (+info)

Comparison of cytogenetics and polymerase chain reaction based detection of the amelogenin gene polymorphism for the diagnosis of freemartinism in cattle. (5/19)

A polymerase chain reaction (PCR) assay which detects a sex-based polymorphism in the bovine amelogenin locus was modified and compared to conventional cytogenetic analysis for diagnosis of freemartinism (XX/XY chimerism) in cattle. The PCR assay is more sensitive than cytogenetic analysis for detection of XY cells, with the limit of detection of the assay falling between 0.2% and 1% XY cells. Seventy-three heifer blood samples submitted for evaluation of freemartinism to the University of Minnesota Diagnostic Laboratory were tested using both cytogenetic and PCR techniques. Poor-quality samples precluded successful lymphocyte culture and recovery of mitotic nuclei for cytogenetic evaluation in 17 cases (23%). Two of these samples (2.7%) also failed to amplify with PCR. There was 100% agreement in the results from the 56 samples that were suitable for testing using both techniques. This PCR-based assay provides an alternative to the more laborious cytogenetic evaluation for diagnosis of freemartinism.  (+info)

Direct observation of hematopoietic progenitor chimerism in fetal freemartin cattle. (6/19)

BACKGROUND: Cattle twins are well known as blood chimeras. However, chimerism in the actual hematopoietic progenitor compartment has not been directly investigated. Here, we analyzed fetal liver of chimeric freemartin cattle by combining a new anti-bovine CD34 antibody and Y-chromosome specific in situ hybridization. RESULTS: Bull-derived CD34+ cells were detected in the liver of the female sibling (freemartin) at 60 days gestation. The level of bull-derived CD34+ cells was lower in the freemartin than in its male siblings. Bull (Y+) and cow hematopoietic cells often occurred in separate clusters. Around clusters of Y+CD34+ cells, Y+CD34- cells were typically observed. The thymi were also strongly chimeric at 60 days of gestation. CONCLUSION: The fetal freemartin liver contains clusters of bull-derived hematopoietic progenitors, suggesting clonal expansion and differentiation. Even the roots of the hematopoietic system in cattle twins are thus strongly chimeric from the early stages of fetal development. However, the hematopoietic seeding of fetal liver apparently started already before the onset of functional vascular anastomosis.  (+info)

Blood chimerism in a girl with Down syndrome and possible freemartin effect leading to aplasia of the Mullerian derivatives. (7/19)

 (+info)

Evidence for almost complete sex-reversal in bovine freemartin gonads: formation of seminiferous tubule-like structures and transdifferentiation into typical testicular cell types. (8/19)

During mammalian sex determination of XY fetuses, SRY induces SOX9 in Sertoli cells, resulting in formation of testes with seminiferous tubules, interstitial Leydig cells and peritubular myoid cells. Meanwhile XX fetuses without SRY develop ovaries. In cattle, most XX heifers born with a male twin, so-called freemartins, develop nonfunctioning ovaries and genitalia with an intersex phenotype. Interestingly, freemartins sometimes develop highly masculinized gonads with seminiferous tubule-like structures despite the absence of SRY. However, in these cases, the degree of masculinization in each gonadal somatic cell type is unclear. Here, we report a rare case of a freemartin Japanese black calf with almost complete XX sexreversal. Gross anatomical analysis of this calf revealed the presence of a pair of small testis-like gonads with rudimentary epididymides, in addition to highly masculinized genitalia including a pampiniform plexus, scrotum and vesicular gland. Histological and immunohistochemical analyses of these masculinized gonads revealed well-defined seminiferous tubule-like structures throughout the whole gonadal parenchyma. In epithelia of these tubules, SOX9-positive supporting cells (i.e., Sertoli cells) were found to be arranged regularly along the bases of tubules, and they were also positive for GDNF, one of the major factors for spermatogenesis. 3beta-HSD-positive cells (i.e., Leydig cells) and SMA-positive peritubular myoid cells were also identified around tubules. Therefore, for the first time, we found the transdifferentiation of ovarian somatic cells into all testicular somatic cell types in the XX freemartin gonads. These data strongly support the idea of a high sexual plasticity in the ovarian somatic cells of mammalian gonads.  (+info)

• 1
• 2
• 3