Oocytes

Oocytes can be unusually large cells in species for which embryonic development takes place away from the mother's body.

Secondary oocytes are released at ovulation. The second meiotic division resumes after penetration by sperm.
In humans, secondary oocytes are fertilized. Eggs are produced only after fertilization of a secondary oocyte.

Diploid stem cells called oogonia divide by mitosis to produce more oogonia and primary oocytes.

Extracts from handisolated nuclear envelopes from frog oocytes were tested for the specific DNAbinding activity to (T2G4)116. A fragment of Tetrahymena telomere from a YAC plasmid was used as a labelled probe in a gelshift assay.

The oocytes of certain amphibians, however, have such large nuclei and such a density of pores that the nuclear envelope of one of the cells may contain more than ten million pores.

Chromosomes of amphibian oocytes having loops suggestive of a lampbrush. Large chromosomes found in amphibian eggs, with lateral DNA loops, extending from chromomeres, producing a brushlike appearance under the microscope.

"b) Unequal cell division in meiosis / 1 ovum and tiny polar bodies produced
b) Primary oocytes form before birth / growth phase before birth
b) Pause in meiosis at prophase I / further development suspended until puberty
b) Pause in meiosis at ...

[L. ovarium - ovary] The female gonad: where primary oocytes develop into mature eggs through oogenesis. It is also responsible for the secretion of several female sex hormones (ie. estradiol and progesterone).

Oral contraceptives (birth control pills) usually contain a combination of hormones that prevent release of FSH and LH, inhibiting development of the follicle so that no oocytes are released.

the primordial female germ cell that divides mitotically to ultimately produce oocytes
Source: Jenkins, John B. 1990. Human Genetics, 2nd Edition. New York: Harper & Row
...

Diploten (diplonema): The stage of meiosis I in which recombination between homologous chromosomes occurs. In females, oocytes are frozen at this stage at birth. Only one proceeds to the completion of meiosis every month during reproductive years.

At birth each female carries a lifetime supply of developing oocytes, each of which is in Prophase I. A developing egg (secondary oocyte) is released each month from puberty until menopause, a total of 400-500 eggs.

nurse cells. Single cells or layers of cells surrounding or adjacent to other cells or structures for which the nurse cells provide nutrient or other molecules (for example, for insect oocytes or Trichinella spp. juveniles).

See also: Oocyte, Cells, Organ, Cell, Human