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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
The liver is the only organ that has the ability to regenerate itself after certain types of damage. As much as 25% of the liver can be removed, and it will still regenerate back to its original shape and size. However, the liver cannot regenerate after severe damage caused by alcohol.
Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
About 80% of major fungal systemic infections are due to Candida albicans. Another form, Candida peritonitis, occurs most often in postoperative patients. A rare disease, Candida meningitis, may follow leukemia, kidney transplant, other immunosuppressed factors, or when suffering from Candida septicemia.
Multiple sclerosis is a condition wherein the body's nervous system is weakened by an autoimmune reaction that attacks the myelin sheaths of neurons.
![Competition can be (a) direct, or (b) indirect interaction among individuals of the same or differen](https://biology-forums.com/gallery/47/medium_33_17_02_12_5_28_58_19442225.jpeg)
![Succession in the intertidal zone involves colonization and competition for limited space among spec](https://biology-forums.com/gallery/47/medium_33_17_02_12_6_53_46_2016316.jpeg)