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Oocyte abnormalities can be caused by a variety of genetic factors affecting different stages in meiosis. [1] Moreover, ageing is associated with oocyte abnormalities since higher maternal age is associated with oocytes with a reduced gene expression of spindle assembly checkpoints which are important in maintaining stability in the genome.
In the antral follicle, there is an antrum containing a follicle liquor, which contains estrogen, to allow the passage from the antral follicle to the Graaf follicle. The follicular antrum moves the oocyte and becomes eccentric; the oocyte is always surrounded by the pellucid zone and by follicular cells that form the oophorus cumulus.
The follicle is now 0.2 mm in diameter Early tertiary: The early tertiary follicle is arbitrarily divided into five classes. Class 1 follicles are 0.2 mm in diameter, class 2 about 0.4 mm, class 3 about 0.9 mm, class 4 about 2 mm, and class 5 about 5 mm. Late tertiary: Fully formed antrum, no further cytodifferentiation, no novel progress
An ovarian follicle is a roughly spheroid cellular aggregation set found in the ovaries. It secretes hormones that influence stages of the menstrual cycle . At the time of puberty , women have approximately 200,000 to 300,000 follicles, [ 1 ] [ 2 ] each with the potential to release an egg cell (ovum) at ovulation for fertilization . [ 3 ]
Follicular waves are best described as the phase when follicles have matured sufficiently and rupture, leading to ovulation. Recent findings into the menstrual cycle in mammals has discovered that 2 or more follicles can develop but only one of the follicles fully matures to release the egg.
The ovarian follicles rupture and release the secondary oocyte ovarian cells. [1] After ovulation, during the luteal phase, the egg will be available to be fertilized by sperm. If it is not, it will break down in less than a day. Meanwhile, the uterine lining (endometrium) continues to thicken to be able to receive a fertilized egg.
Human fertilization is the union of an egg and sperm, occurring primarily in the ampulla of the fallopian tube. [1] The result of this union leads to the production of a fertilized egg called a zygote, initiating embryonic development. Scientists discovered the dynamics of human fertilization in the 19th century. [2]
Diagram of stages of embryo development to a larval and adult stage. In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell (spermatozoon). [1]