oocyte

Examples of oocyte in the following topics:

• Gametogenesis (Spermatogenesis and Oogenesis)

  • The cell starting meiosis is called a primary oocyte.
  • This results in the primary oocyte finishing the first meiotic division.
  • At ovulation, this secondary oocyte will be released and travel toward the uterus through the oviduct.
  • A primary oocyte begins the first meiotic division, but then arrests until later in life when it will finish this division in a developing follicle.
  • This results in a secondary oocyte, which will complete meiosis if it is fertilized.

• Fertilization

  • Fusion between the oocyte plasma membrane and sperm follows and allows the sperm nucleus, centriole, and flagellum, but not the mitochondria, to enter the oocyte.

• Female Reproductive Anatomy

  • Oocytes develop in (a) follicles, located in the ovary.
  • The (b) follicle in this light micrograph has an oocyte at its center.

• Physiological Processes in Sponges

  • Sponges may also become sequentially hermaphroditic, producing oocytes first and spermatozoa later.
  • Oocytes arise by the differentiation of amoebocytes and are retained within the spongocoel, whereas spermatozoa result from the differentiation of choanocytes and are ejected via the osculum.
  • Spermatozoa carried along by water currents can fertilize the oocytes borne in the mesohyl of other sponges.

• Human Gestation

  • Twenty-four hours before fertilization, the egg has finished meiosis and become a mature oocyte.
  • In humans, fertilization occurs soon after the oocyte leaves the ovary.

• Pineal Gland and Gonads

  • In some mammals, melatonin has an inhibitory affect on reproductive functions by decreasing production and maturation of sperm, oocytes, and reproductive organs.