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External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. [1] It is contrasted with internal fertilization , in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism.
Sperm motility describes the ability of sperm to move properly through the female reproductive tract (internal fertilization) or through water (external fertilization) to reach the egg. Sperm motility can also be thought of as the quality , which is a factor in successful conception ; sperm that do not "swim" properly will not reach the egg in ...
The biologist Thierry Lodé proposed (2001, 2012) five modes of reproduction based on the relationship between the zygote (fertilised egg) and the parents: [1] [2]. Ovuliparity: fertilisation is external, the oocytes being released into the environment and fertilised outside the body by the male. [1]
First, external fertilization protects against paternity loss; however, sneaker tactics and strong sperm competition have evolved many times. Second, the earlier release of eggs than sperm gives females an opportunity to flee; however, in many paternal care species, eggs and sperm are released simultaneously.
The egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. [1] Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals, monotremes (four species of echidna, and the platypus) are uniquely oviparous.
“We’ve seen total costs average $15,000 to $20,000 per egg-freezing cycle, with many patients needing two cycles.” Here’s a look at how those costs break down, according to FertilityIQ :
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Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization. The fertilized egg cell is known as the zygote. [2] [5] To prevent more than one sperm fertilizing the egg , fast block and slow block to polyspermy are used. Fast block, the membrane ...