Crossing over at prophase I results in the linked genes (those on the same chromosome) becoming unlinked and separated. Prophase I is this first stage of meiosis, the chromosomes condense, form tetrads<span>, and exchange DNA. The nucleolus and nuclear envelope disappear.</span>
Answer:
Cells have different shapes because theydo different things. ... The shapes ofcells have evolved to help them carry out their specific function in the body, so looking at a cell's shape can give clues about what it does. Neurons are cells in the brain and nervous system.
The answer is; Varicosities are recognized by the enlargement of the veins. Superficial veins are most likely involved because they have little support from surrounding tissues. The veins have become tortuous and dilated because of incompetent valves that allow the blood to pool, stretching the vein walls. The likely cause in this patient's case is her pregnancies, because the enlarged uterus exerts download pressure on groin vessels, restricting return blood flow to the heart.
