Normal Differentiation (normal + differentiation)

Distribution by Scientific Domains

Selected Abstracts

Development of the genital ducts and external genitalia in the early human embryo

Yasmin Sajjad
Abstract The course of development of the human genital tract is undifferentiated to the 9th week of development. At this time two symmetrical paired ducts known as the mesonephric (MD) and paramesonephric ducts (PMD) are present, which together with the urogenital sinus provide the tissue sources for internal and external genital development. Normal differentiation of the bipotential external genitalia and reproductive ducts are dependent upon the presence or absence of certain hormones. Masculinization of the internal and external genitalia during fetal development depends on the existence of two discrete testicular hormones. Testosterone secreted from Leydig cells induces the differentiation of the mesonephric ducts into the epididymis, vasa deferentia and seminal vesicles, whereas anti-Müllerian hormone (AMH) produced by Sertoli cells induces the regression of the paramesonephric ducts. The absence of AMH action in early fetal life results in the formation of the fallopian tubes, uterus and upper third of the vagina. In some target tissues, testosterone is converted to dihydrotestosterone, which is responsible for the masculinization of the urogenital sinus and external genitalia. [source]

Effect of Diets Formulated with Native Peruvian Plants on Growth and Feeding Efficiency of Red Pacu (Piaractus brachypomus) Juveniles

Maria E. Palacios
We evaluated the effects of casein-based semipurified diets, alone or supplemented with native Peruvian plants, on growth, feed efficiency, and histology of the digestive tract of red pacu, Piaractus brachypomus, juveniles over an 8-wk feeding trial. Three tanks were randomly assigned to one of four casein,gelatin (40:8) diets containing a supplement of 15% wheat meal (control) or an identical level of substitution of three South American native plant as follows: camu-camu fruit (Myrciaria dubia), aguaje fruit (Mauritia flexuosa), or maca tuber meal (Lepidium meyenii). The fish (initial weight, 2.04 ± 0.06 g) were fed experimental diets at decreasing feeding rates from 4 to 2.6% of body weight. After 8 weeks of feeding, fish fed a diet supplemented with maca meal showed significantly higher (P < 0.05) weight gain, specific growth rate, protein efficiency ratio (PER), apparent net protein utilization (NPU), and instantaneous feed intake than fish fed other diets. Feed conversion ratio (FCR), PER, and NPU in fish fed the casein,gelatin diet supplemented with maca meal were among the best ever reported in the scientific literature, 0.64 ± 0.03, 3.13 ± 0.15 and 23.8 ± 2.0, respectively. The camu-camu meal had a negative impact on diet palatability and utilization, which resulted in slower growth. The stomach, intestine, pancreas, and pyloric caeca at the start and end of the experiment showed normal differentiation and appearance of cells and tissues. The liver parenchyma showed lipid infiltration and pigment accumulation in all samples at the initiation of the experiment and may be attributed to the period of decreased feed intake prior to the study. At the end of the study, similar histopathologies were recorded in all samples from the control and camu-camu groups. Normal liver histology (polyhedral hepatocytes with centrally located nuclei) was observed in two of three samples from the maca group and all the samples from the group that was fed the aguaje-supplemented diet. [source]

Autopsy case of thanatophoric dysplasia: Observations on the serial sections of the brain

Katsuyuki Yamaguchi
The neuropathological findings in an autopsy case of thanatophoric dysplasia (TD) with serial sections of the brain are described here. This patient was a female infant, born at 33 weeks gestation, who died on day 1. Skeletal anomalies, consisting of short limbs, a small thorax, short ribs, thick cortical vertebral body substance and sternum substance, and hypoplastic lungs, were compatible with typical phenotypic features of TD. The brain weighed 370 g, showing a cloverleaf megalencephaly. A computerized 3-D reconstruction technique visualized clearly abnormal deep sulci arranged perpendicular to the neuraxis on the inferior surface of the temporal lobe, and peculiar configurational changes of the lateral ventricle. In particular, the inferior horn showed an unusual complex form. Dysgenetic changes were largely located in the anterior temporal lobe as follows: cortical polymicrogyria; leptomeningeal heterotopia with discontinuity of the subpial basement membrane; serpentine arrangement of pyramidal cells of the cornu ammonis (CA)1 of the hippocampus; hypoplastic dentate gyrus; hyperplasia of the amygdaloid body; and heterotopic nodules of neuroblasts or glioblasts in the periventricular white matter. Apart from the temporal lobe, the cerebral pia mater showed unusual fusion of two facing sheets in a sulcus and ectopia of nerve cells, and the cerebellar vermis was small. The findings observed here indicate that overgrowth and lack of growth can coexist in the TD brain, suggesting that some interaction(s) between the mesenchyme and the nervous tissue may play a role in normal differentiation of these two cell lines. [source]

Functional imaging: New views on lens structure and function

Paul J Donaldson
SUMMARY 1.,We have developed an experimental imaging approach that allows the distribution of lens membrane proteins to be mapped with subcellular resolution over large distances as a function of fibre cell differentiation. 2.,Using this approach in the rat lens, we have localized precisely histological sites of connexin 46 cleavage, quantitatively mapped changes in gap junction distribution and fibre cell morphology and correlated these changes to differences in intercellular dye transfer. 3.,Profiling of glucose transporter isoform expression showed that lens epithelial cells express GLUT1, whereas deeper cortical fibre cells express the higher-affinity GLUT3 isoform. Near the lens periphery, GLUT3 was located in the cytoplasm of fibre cells, but it underwent a differentiation-dependent membrane insertion. 4.,Similarly, the putative adhesion protein membrane protein 20 is inserted into fibre cell membranes at the stage when the cells lose their nuclei. This redistribution is strikingly rapid in terms of fibre cell differentiation and correlates with a barrier to extracellular diffusion. 5.,Our imaging-orientated approach has facilitated new insights into the relationships between fibre cell differentiation and lens function. Taken together, our results indicate that a number of strategies are used by the lens during the course of normal differentiation to change the subcellular distribution, gross spatial location and functional properties of key membrane transport proteins. [source]