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A1. Cytoplasm is the "fluid" inside the egg. It's not really a fluid, but more like a gel. While maturing in the follicle, the egg has to make and store all the "food" it needs to carry it through the first two division cycles (1 to 2 cell, 2 cell to 4 cell). This "food" is stored in the cytoplasm. The cytoplasmic "pantry" has to be stocked up, otherwise the embryo prematurely runs out of food and stops growing before it can make more food. The end.
What you are referring to is an experimental procedure called "cytoplasmic transfer" and, yes, its been banned in the US (Whew! and for good reason too). The cytoplasm that was transferred from the younger women's egg to the older women's egg contained mitochondria. Mitochondria are organelles (equivalent to the organs in the body) that are responsible for generating the energy "currency" of the cell, a molecule called ATP. In aging eggs, the mitochondria are tired and do not produce as much ATP as when they were young. Accordingly the developmental potential of the egg is compromised. Part of the cytoplasmic matuartion involves making and storing adequate reserves of ATP for development. Hence, transferring "young" mitochondria can improve cytoplasmic maturation. The downside to cytoplasmic transfer, and the reason it was banned, is because mitochondria also contain DNA which is specific to our family lineage. A mismatch of mitochondrial DNA can cause problems in future generations.
A2. Yes, thats exactly right. Some follicles are not clearly visible by ultrasound on cycle day 3. As the grow, they become clear on the ultrasound.
On a NATURAL cycle, some antral folicles "wake up" and become responsive to FSH. What causes some to "wake up" while others continue to "sleep" is a mystery. All of the antral follicles that "woke up" on that cycle (the actual number will depend on age and other factors) will begin to grow in response to FSH released from the pituitary gland. In a NATURAL cycle, the pitutary makes only enough FSH to sustain the growth of one follicle. THis is the only follicle that will continue to grow, rupture and release the egg (ovulation). The other follicles stop growing and "die off". In a STIMULATED cycle, the medications that contain FSH (Follistim, Gonal F, Menopur, etc) increase the available FSH and sustain the growth of all the follicles that "woke up" on that cycle. Some follicles grow faster than others, but the number of antral follicles that "woke up" on that cycle does not change in response to the stimulation medications.
The term "poor responder" is incorrect since the follicles are responding to the FSH containing stimulation medications, its just that there were just fewer antral follicles to stimulate. This is usually a result of advanced maternal age because there are fewer follicles left in the ovary. Giving more FSH will not alter the number of antral follicles that begin each cycle, just modulate their rate of growth. If it was as simple as just giving women more stimulating medication to make more follicles, every woman would have a gazillion follicles on every cycle.
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