The extracellular matrix protein pattern in the canine neoplastic mammary gland.

Extracellular matrix (ECM) proteins in the mammary gland provide structure and regulate its development and homeostasis. Alterations in its structure can regulate and support pathogenesis, like breast tumors. Aiming to identify the health and tumoral canine mammary ECM scaffold protein profile by immunohistochemistry, the decellularization process was carried out to remove the cellular content. Additionally, it was verified the influence of health and tumoral ECM on the attachment of health and tumoral cells. The types I, III, IV, and V structural collagens were scarce in the mammary tumor, and ECM fibers were disorganized. Vimentin and CD44 were more common in mammary tumor stroma, suggesting a role in cell migration that results in tumor progression. Elastin, fibronectin, laminin, vitronectin, and osteopontin were similarly detected under healthy and tumor conditions, providing the attachment of normal cells in healthy ECM, while tumoral cells were able to attach in tumoral ECM. The protein pattern demonstrates ECM alteration in canine mammary tumorigenesis, presenting new knowledge on mammary tumor ECM microenvironment.

Development of the central nervous system in equine twin fetuses derived by somatic cell nuclear transfer.

Because of the growing importance of horses in leisure and several sports, somatic cell nuclear transfer (SCNT) is being used more frequently for cloning animals for performance and reproductive purposes. However, because of the need to perforate the zona pellucida during microsurgical reconstruction of the oocyte, it is possible that SCNT-derived embryos undergo premature hatching, resulting in embryo bisection and twinning. Therefore, because equine twin pregnancies often lead to abnormal embryo development and pregnancy failure, we performed a detailed comparative assessment of equine twin fetuses derived by SCNT with particular attention on the development of the central nervous system at 40 and 60 days gestation. The results of this study indicate that although cloned twin embryos show small differences in size, they do not exhibit apparent macro- or microscopic developmental discrepancies in the central nervous system, suggesting that the twining phenomenon resulting from SCNT does not affect fetal differentiation.

Reproductive system development in male and female horse embryos and fetuses: Gonadal hyperplasia revisited.

In horses, pregnancy is characterized by high levels of maternal estrogens that are produced largely by the interstitial tissue inside the gonads of the offspring, associated with a physiological gonadal hyperplasia, that is uncommon in other species. However, a detailed structural-functional understanding of the early stages of gonadal development and hyperplasia has remained elusive in horse pregnancy because of the lack of substantial data. The goal of this study was to describe the genital organs' development in 19 early horse embryos and fetuses (days 20-140 of gestation) of both sexes by means of anatomy, histology, stereology, and immunohistochemistry, with a specific focus on gonadal hyperplasia and interstitial tissue development. Gonadal hyperplasia with similar amounts of interstitial cells was observed in both sexes, but only during the early stage of development (days 40-90). Surprisingly, a higher degree of hyperplasia, characterized by larger amounts of interstitial cell-rich areas, was seen in fetal ovaries from 90 days of gestation onwards. Another novel aspect was that parallel to the hyperplasia of the interstitial cells, a much more precocious and pronounced differentiation of germinal cells was seen in the ovary, characterized by an earlier peak and decrease of DAZL and OCT protein immune markers. In conclusion, a reduced degree of hyperplasia and interstitial tissue in the fetal testis after 90 days of gestation suggests the existence of a more efficient mechanism regarding the synthesis of estrogen precursors as a structural or physiological difference between both fetal sexes, which warrants further investigation.