Vol 49, No 4 (2018)

Mesenchymal stem cells (MSCs) are widely used in experimental research on cell therapy intended for the stimulation of repair processes in damaged tissues and organs. The present review summarizes the results of studies devoted to the possible directions of MSC differentiation after the transplantation of these cells into damaged nerves or special engineered structures of biological and artificial biodegradable materials that join the ends of a damaged nerve (nerve conduits). Data on exogenous MSC differentiation into Schwann cells, pericytes, smooth muscle cells, endotheliocytes, and other cell types are presented. Methods for preliminary MSC differentiation in vitro and examples of beneficial effects of these cells transplanted into damaged conductive nerves on nerve regeneration are given. The fate of exogenous MSCs placed into an unnatural biological niche remains poorly characterized and requires further studies, as emphasized in the review.

It was demonstrated that individual linear growth of the Margaritifera margaritifera freshwater bivalve mollusk in Syuskyuyanioki River is accompanied by natural biorhythms. The periods of biorhythms, as well as growth retardation coefficients, vary widely and differ in different individuals. The periods of biorhythms in individual ontogenesis are approximately constant. Mean values of the growth retardation coefficients and periods do not depend on the biotope and are 0.114 ± 0.003 year^–1 and 3.88 ± 0.06 years, respectively. The possibility of thermodynamic nature of biorhythms is discussed.

This study continues our previous experiments intended to elucidate the role of sucrose in a figured wood formation in silver birch (Betula pendula Roth var. carelica). The purpose of the study was the investigation of the role of sucrose in the regulation of cell division in the cambial zone. Using an earlier-developed technique, sucrose solutions of different concentrations have been delivered into trunk tissues of silver birch. A microscopic analysis of samples collected 28 days after the beginning of the experiment has shown that an increased sucrose concentration in an exogenous solution causes an increase in the frequency of anticlinal cell divisions in the cambial zone. In the case of high sucrose concentrations (10 or 20%), the zone of anticlinal divisions is significantly wider than in variants with low sucrose concentrations, since anticlinal divisions are observed on both phloem and xylem sides and at a larger distance from rays. A comparison of the obtained results with the previous experiments shows that the increased frequency of anticlinal divisions in cambial cells observed in the case of application of 10 or 20% sucrose solutions coincides with an increased parenchymatization of tissues. A revealed localization of anticlinal divisions within the cambial zone indicates that, in the case of the exogenous sucrose uptake, the morphogenesis of conductive tissues in silver birch (Betula pendula Roth var. pendula) occurs in the same way as in Karelian birch (Betula pendula Roth var. carelica). Data presented in this paper agree with the earlier hypothesis that the formation of figured wood similar to that of Karelian birch occurs due to increased sucrose content in trunk tissues.

The initiation of somatic embryos and their propagation in the long-term proliferating embryonal suspensor mass of Larix sibirica were studied. It was found that the increase in the number of somatic embryos in the embryogenic culture occurred as a result of cleavage of the globules of the somatic embryo and the suspensor; it less often occurred as the result of budding of the suspensor and the separation of the embryonal tubes of the suspensor. In the case of long-term proliferating cell lines (more than 8 years), the rate of cleavage did not weaken. A conclusion on the identity of morphogenic processes underlying the development of zygotic and somatic embryos of conifers is made, which is confirmed by the concept of T.B. Batygina (1999) on the parallelism of their development in vivo and in vitro.

At present, male infertility remains an urgent medical concern. From year to year, despite advances in methods of diagnosis and treatment, medicine encounters an increasing number of infertile couples with male infertility playing a leading role. Prerequisites for fertility disorders very frequently appear in childhood. Urologists consider cryptorchidism a leading cause of male infertility. The aim of our study was to establish the relationship between testicular descent to the scrotum and the age of the fetus. Material and methods. The study was conducted using 195 specimens of male fetuses aged 4–10 months with 81.0–375.0 mm parietalcoccygeal length (PCL) using the methods of macromicroscopic, conventional, and microslide preparation under control of binocular loupes and morphometry. Results. At the beginning of the fetal period of human ontogenesis (fetuses 81.0–135.0 mm PCL), the right and left testicles are mainly located above the corresponding deep inguinal ring and they are less often located in a region of the iliac fossae. An analysis of topographic and anatomical features of the male reproductive glands in 5-month-old fetuses (136.0–185.0 mm PCL) revealed that the testicles were located within the large pelvis, with the lower end of both the right and left testicles located above the entrance to the deep inguinal ring at a distance that equals the length of the pelvic part of the gubernaculum testis—3.2 ± 0.3 mm (right) and 2.8 ± 0.2 mm (left). In 11 fetuses aged 7 months (231.0–270.0 mm PCL), the lower ends of the testicles and their gubernaculum testis are immersed in the corresponding deep inguinal ring. In eight fetuses, the testicles were within the deep inguinal ring. A combination of many factors contributes to the final migration of a testicle through the inguinal canal into the scrotum (fetuses: 270.0 cm–290.0 mm PCL), including muscle contraction of the anterolateral abdominal wall, an increase in intra-abdominal pressure, contractile capacity of the gubernaculum testis of the testicle, the vaginal process of the peritoneum, and the neuro-muscular system. We believe that the gubernaculum testis is a particularly significant factor in testicular descent to the scrotum. The gubernaculum testis is maximally developed prior to migration of a testicle through the inguinal canal (eighth month of antenatal development), as evidenced by the prevalence of smooth muscle cells over connective tissue elements. An analysis of testicular topography in fetuses aged 9 months (311.0–345.0 mm PCL) revealed that testicles were located in the scrotum in nine fetuses, near the superficial inguinal ring in six fetuses, within the inguinal canal in four cases, and in the deep inguinal ring in one case. In fetuses aged 10 months (346.0–375.0 mm PCL), testicles were located in the scrotum in 13 cases and within the inguinal canal in seven cases. According to our research, the fusion of layers of the vaginal process of the peritoneum occurs in fetuses aged 9–10 months, resulting in the disappearance of the communication of its cavity with the peritoneum. A delay in the fusion of the peritoneal vaginal process layers at the end of the fetal period is an anatomic prerequisite for the occurrence of congenital inguinal-scrotal hernias. Conclusions. It has been found that the rate of testicular descent to the scrotum does not always coincide with the corresponding stage of fetal development. An accelerated development of the gubernaculum testis in fetuses aged 5–8 months is a major factor of heterochronic development of a testicle and subsequent testicular descent into the scrotum.

Adults of Paradise fish Macropodus opercularis are easily maintained in the laboratory. The fertilized eggs of Paradise fish were natural inseminated and incubated in room temperature (range 22.5 to 25.7°C). We carefully observed the process of embryonic development and divided them into 28 stages based on diagnostic features of the developing embryos. The principal diagnostic features are the number and size of blastomeres, form of the blastoderm, extent of epiboly, development of the central nervous system, number and form of somites, optic and otic development, heart development, blood circulation, the size and movement of the body, and development of the tail.