Transdifferentiation potential of ciliary and pigment epithelial cells in lower vertebrates and mammals

Cellular composition of the peripheral region of the eye in amphibians and mammals as well as embryonic fissure in amphibians was studied. Different distributions of proliferating cells in retinal pigment epithelium have been revealed in adult amphibians (newt, axolotl, and Xenopus). Single cells incorporated [ 3H]thymidine in the newt and Xenopus; 0.4% cells, in the axolotl. An embryonic fissure was observed in the eye of the axolotl. Pigment epithelial cells in the embryonic palpebral region actively proliferated: about 20% cells incorporated [ 3H]thymidine. Proliferating cells were also localized in the ciliary marginal zone of the retina in all studied amphibians, particularly, in the axolotl. In newborn hamsters, [ 3H]thymidine-labeled cells have been revealed in the pigment epithelium as well as in the outer pigmented and inner unpigmented layers of the ciliary body. Proliferative activity of the peripheral regions of the eye is due to eye growth in adult amphibians and newborn hamsters. After retinectomy, the retina is regenerated from the cells of the growth ciliary marginal zone in all amphibians, pigment epithelial cells in the newt, and pigment epithelial cells of the embryonic fissure in the axolotl. Heterogeneous composition of the pigment epithelium in the newt and axolotl reflects high transdifferentiation potential of these regions. Structural comparison of the peripheral region of the eye in amphibians and mammals demonstrate that the ciliary body of mammals containing stem cells is homologous to the ciliary marginal zone of amphibians containing multipotent cells

The content of lutein and its oxidized forms in human eye tissues in prenatal development

ABSTRACT Purpose. To study the presence of carotenoids in the tissues of prenatal human eye in the course of its development. Material and methods. The eyes were obtained from abortive human fetuses of 12-28 weeks of pregnancy. The fetuses were brought to the Kulakov Research Center of Obstetrics, Gynecology, and Perinatology, the Russian Academy of Medical Sciences, from licensed institutions of the Ministry of Public Health, working under the Russian Federation legislation on citizen health protection, and in accordance with the approved list of medical indications. The ages of the fetuses were determined by an obstetrician. Totally, 49 samples of eye tissues from human fetuses at different pregnancy ages were used. The content of carotenoids and their oxidized forms was measured by high-performance liquid chromatography (HPLC) technique. Results. The presence of lutein and/or its oxidized forms was estimated by HPLC in the tissues of prenatal human eyes (cornea, sclera, optic nerve, retinal pigment epithelium with choroid, ciliary body with iris, vitreous body). Conclusion. The finding of lutein or oxidized forms of lutein in tissues of the human eye in the course of prenatal development is of essential interests for understanding physiology of the prenatal and postnatal eye

The Eurasian Modern Pollen Database (EMPD), version 2

The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60 % from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019)