This work is a trial to evoke hind limb regeneration by application of alternating electric current of different wave shapes; sine, square and triangular with different frequencies; 50, 500, 5000 and 50000 Hz. It was found that application of an alternating electric current with different wave shapes partially enhances limb regeneration in the prometamorphic stage (number 56) of Bufo regularis Reuss after amputation at the mid shank level. Regenerates were ranging from limbs with complete number of toes to hypomorphic limbs without toes. The enhancing effect was suggested to be due to stimulation of both the active sties of epithelial DNA, which are involved in the transcription processes. And nerve regeneration. Square and sine waves produced more enhancing effect due to being at peak maximum for periods relatively longer than triangular waves. Application of 50 Hz and 50000 Hz was more effective than that of 500 Hz and 5000 Hz, suggesting its interference with the natural regeneration current to produce the most compatible frequencies creating resonance with the stump tissues.

This work is a trial to evoke hind limb regeneration by application of alternating electric current of different wave shapes; sine, square and triangular with different frequencies; 50, 500, 5000 and 50000 Hz. It was found that application of an alternating electric current with different wave shapes partially enhances limb regeneration in the prometamorphic stage (number 56) of Bufo regularis Reuss after amputation at the mid shank level. Regenerates were ranging from limbs with complete number of toes to hypomorphic limbs without toes. The enhancing effect was suggested to be due to stimulation of both the active sties of epithelial DNA, which are involved in the transcription processes. And nerve regeneration. Square and sine waves produced more enhancing effect due to being at peak maximum for periods relatively longer than triangular waves. Application of 50 Hz and 50000 Hz was more effective than that of 500 Hz and 5000 Hz, suggesting its interference with the natural regeneration current to produce the most compatible frequencies creating resonance with the stump tissues.

In this work, a new quaternion-based method for color image watermarking is proposed. In this method, a
novel set of quaternion radial substituted Chebyshev moments (QRSCMs) is presented for robust geometrically
invariant image watermarking. An efficient computational method is proposed for highly accurate,
fast, and numerically stable QRSCMs in polar coordinates. The proposed watermarking method consists of
three stages. In the first stage, the Arnold transform is used to improve the security of the watermarking
scheme by scrambling the binary watermark. In the second stage, the proposed accurate and stable QRSCMs
of the host color image are computed. In the third stage, the encrypted binary watermark is embedded into
the host image by employing the quantization technique on selected-magnitude QRSCMs where the watermarked
color image is obtained by adding the original host color image to the compensation image. Then,
the binary watermark can be extracted directly without using the original image from the magnitudes of
QRSCMs. Numerical experiments are performed where the performance of proposed method is compared
with the existing quaternion moment-based watermarking methods. The comparison clearly shows that the
proposed method is very efficient in terms of the visual imperceptibility capability and the robustness under
different attacks compared to the existing quaternion moment-based watermarking algorithms.

The mitochondrial changes were studied, using transmission electron microscope, during hind limb regeneration in a larval stage (number 53) of the Egyptian toad, Bufo regularis Reuss at intervals, one, three five and seven days after amputation at the prospective knee joint level. Mitochondria were found in both control and experimental animals having different forms, sizes and positions. Cristae were noticed obviously extended reflecting continuous metabolic activities. Large electron dense granular masses were observed within the mitochondrial matrix in both control and experimental animals during the first five days after amputation. These granules decrease in later stages. It is suggested that mitochondria are active during different stages of regeneration. The variations in form, size and position of mitochondria might be related to its functional performance. The electron dense masses are suggested to be storage material and are consumed during cellular growth in the early phases of regeneration.

The ultrastructure of muscle dedifferentiarion and redifferentiation was observed during hind limb regeneration in a larval stage (number 53) of Bufo regularis. It was found that the young, forming muscle fibres with low level of differentiation, can easily loose its morphological characteristic features and dedifferentiate into blastemal cells from which new muscle fibres redifferentiate. Dedifferentiated cells were acquiring characteristics of actively growing cells reflecting their transformation into blastemal mesenchyme cells and then into redifferentiated muscle fibres. Satellite cells were not observed in the formation of the new myotubes. The absence of satellite cells in muscle fibres, in the present study, was suggested to be due to the low level of differentiation of muscle fibres, since the observed cells were either myogenic cells or early differentiating muscle fibres with incomplete myofibril set. Cells must be confined to the well differentiated mature muscles. Macrophages were suggested to induce young muscle fibres differentiation via releasing soluble factors during removal of cellular debris.

Two different types of electrical currents, alternate current (AC) with the frequency of 50 Hz/second and direct current (DC) at the same strength 0.5 milliampere were applied to the amputated hind limbs of a premetamorphic stage (number 56) of the tadpole of the Egyptian toad, Bufo regularis Reuss to compare between their effects on the regenerative capacity after transection at the mid shank level. DC was found to have a partial enhancing effect. AC was found to have a slight retarding effect. It was suggested that the low enhancing effect of DC might be due to metal toxicity of the electrode products and interference of the applied current with the natural regeneration current. Also, the retarding effect of AC might be due to nerve damage, blocking of the natural regeneration current and disturbance of orientation of iron binding proteins.

The interest for retinoic acid (RA) has been increased the last few years, because of its central role in the coordination of development and homeostasis. The present study aims to explore the differential effect of different concentrations of RA during morphogenesis of the chick embryo. Fertilized eggs of Gallus domesticus were injected with a single dose of 0.5 µg, 1 µg or 2 µg of RA dissolved in 1 µl of dimethylsulphoxid (DMSO). Injections were carried out after three days of incubation. RA treatment induced teratogenic effect during the morphogenesis of the developing chick embryos. The defects included malformations in the brain, head, eyes, nostrils, beak, trunk region, fore- and hind-limbs and tail region. The explanation of the RA effect based on the disturbance of normal pattern of expression of genes concerned with the process od morphogenesis. Where the excess of the exogenous RA caused overexpression of genes resulted in several malformations in the developing embryo. The higher concentrations of RA in the present work induced the production of large amounts of the catabolic enzymes (cyps) that degraded RA and minimized the teratogenic effect of RA to a level lower than that induced by lower concentration of RA. The differential effect of different concentrations of RA was controlled by the degrading enzymes through a feedback controlling system.

The interest for retinoic acid (RA) has been increased the last few years, because of its central role in the coordination of development and homeostasis. The present study aims to explore the differential effect of different concentrations of RA during morphogenesis of the chick embryo. Fertilized eggs of Gallus domesticus were injected with a single dose of 0.5 µg, 1 µg or 2 µg of RA dissolved in 1 µl of dimethylsulphoxid (DMSO). Injections were carried out after three days of incubation. RA treatment induced teratogenic effect during the morphogenesis of the developing chick embryos. The defects included malformations in the brain, head, eyes, nostrils, beak, trunk region, fore- and hind-limbs and tail region. The explanation of the RA effect based on the disturbance of normal pattern of expression of genes concerned with the process od morphogenesis. Where the excess of the exogenous RA caused overexpression of genes resulted in several malformations in the developing embryo. The higher concentrations of RA in the present work induced the production of large amounts of the catabolic enzymes (cyps) that degraded RA and minimized the teratogenic effect of RA to a level lower than that induced by lower concentration of RA. The differential effect of different concentrations of RA was controlled by the degrading enzymes through a feedback controlling system.

The interest for retinoic acid (RA) has been increased the last few years, because of its central role in the coordination of development and homeostasis. The present study aims to explore the differential effect of different concentrations of RA during morphogenesis of the chick embryo. Fertilized eggs of Gallus domesticus were injected with a single dose of 0.5 µg, 1 µg or 2 µg of RA dissolved in 1 µl of dimethylsulphoxid (DMSO). Injections were carried out after three days of incubation. RA treatment induced teratogenic effect during the morphogenesis of the developing chick embryos. The defects included malformations in the brain, head, eyes, nostrils, beak, trunk region, fore- and hind-limbs and tail region. The explanation of the RA effect based on the disturbance of normal pattern of expression of genes concerned with the process od morphogenesis. Where the excess of the exogenous RA caused overexpression of genes resulted in several malformations in the developing embryo. The higher concentrations of RA in the present work induced the production of large amounts of the catabolic enzymes (cyps) that degraded RA and minimized the teratogenic effect of RA to a level lower than that induced by lower concentration of RA. The differential effect of different concentrations of RA was controlled by the degrading enzymes through a feedback controlling system.

Glycogen and total protein contents were studied during hind limb regeneration in a metamorphic stage (number 58) of the Egyptian toad, Bufo regularis Reuss after amputation at the mid shank under combined effect of insulin injection and electrical stimulation with different currents (3, 5 and 10 mA). Histochemical observations revealed a decrease in glycogen content after five and seven days of amputation rather than after one and three days. Tissues of the regenerates were active in protein synthesis in control and treated animals. It was suggested that combined effect of insulin injection and electrical stimulation on the amputated hind limbs of a metamorphic stage (number 58) of the Egyptian toad, Bufo regularis Reuss at the mid shank enhanced the synthesis of proteins. The decreased amount of glycogen and other polysaccharides may be due to their consumption as a result of anaerobic respiration and acceleration of proliferative activity of tissues of regenerates.