Chest Radiology > Pathology > Atelectasis > General. Atelectasis is collapse or incomplete expansion of the lung or part of the lung. This is one of the most common findings on a chest x-ray. It is most often caused by an endobronchial lesion, such as mucus plug or tumor.
A Labradoodle, a crossbreed between a poodle and a retriever. A crossbreed or crossbred usually refers to an organism with purebred parents of two different breeds, varieties, or populations.
Crossing over (genetic recombination) is the process where homologous chromosomes pair up with each other and exchange different segments of genetic material to form recombinant chromosomes. It occurs between prophase 1 and metaphase 1 of meiosis. As an exception , it can ALSO OCCUR IN MITOSIS which may result in heterozygosity. But the frequency of crossing over is much higher in meiosis. Cross over events happen approximately 57 times in males and around 75 times in females during meiosis . Mitotic crossing over take place when homologous chromosomal segments are accidentally paired in asexual cells such as body cells.