1. The development of the amphiaster is associated with the formation of two semisolid masses within the more fluid egg substance. 2. The elongation of the egg during cleavage is possibly produced as a consequence of the mutual pressure of these two growing semisolid masses. 3. The division of the egg into two blastomeres consists essentially in a growth, within the egg, of two masses of materi...

the aim of current study was to determine the effects of vitamin c on bone mineral density (in terms of osteoporosis), eggshell quality and investigation of correlation between these factors in laying hens reared under normal condition. one hundred and ninety two 24 - weeks - old laying hens diet was supplemented with 4 levels of vitamin c (0, 250, 500 and 750 mg/kg diet). the experimental desi...

This study attempts to observe and record early embryonic developments of the orange mud crab, Scylla olivacea. The period taken by the eggs to hatch was 8 days and the colour of the eggs gradually changed from yellow to brown, gray and dark gray. During the embryonic development, the developing embryos reached the blastula stage within 24 hours with a mean egg diameter of 329.91 µm ± 6.62. The...

During the first three cleavage divisions of the egg nuclei a precise sequence of spindle orientation and elongation parallel to the longitudinal axis of the egg is apparently involved in positioning one nucleus among the polar granules at the posterior pole of the egg. The size of this nucleus, and the position at which the egg cleaves when pole cell formation occurs, appear to constitute part...

This study attempts to observe and record early embryonic developments of the orange mud crab, Scylla olivacea. The period taken by the eggs to hatch was 8 days and the colour of the eggs gradually changed from yellow to brown, gray and dark gray. During the embryonic development, the developing embryos reached the blastula stage within 24 hours with a mean egg diameter of 329.91 µm ± 6.62. The...

Formation of the first cleavage furrow in the telolecithal egg of Loligo was studied with the electron microscope . Before the actual furrow forms, a dense filamentous band develops below the plasma membrane from membrane-bounded dense bodies which appear to be Golgi-derived . The egg surface is thrown into a number of longitudinal folds which parallel the furrow and eventually become incorpora...

Stages of normal sexual reproduction between pollen germination and egg maturation are described for interior spruce. These prezygotic stages were studied by light and electron microscopy in more detail than was possible in previous studies, and new observations have been made. Sperm (male gametes) formation and the organelles that accompany the sperm within the pollen tube are described. The p...

The reorganization of epithelial sheets into tubes is a fundamental process in the formation of many organs, such as the lungs, kidneys, gut, and neural tube. This process involves the patterning of distinct cell types and the coordination of those cells during the shape changes and rearrangements that produce the tube. A better understanding of the cellular and genetic mechanisms that regulate...