Oogenesis and fertilization report

20
OOGENESIS AND FERTILIZATION Santos, Santuyo, Villena and Dao-ang Reporters :

Transcript of Oogenesis and fertilization report

Page 1: Oogenesis and fertilization report

OOGENESIS AND FERTILIZATION

Santos, Santuyo, Villena and Dao-angReporters :

Page 2: Oogenesis and fertilization report

OOGENESIS

Page 3: Oogenesis and fertilization report

OOGENESIS

OOGENESIS:- is a type of gametogenesis, which ova, or egg cells,

develop within the tissue of the ovary.

Where the egg cells developed.

Page 4: Oogenesis and fertilization report

PRIMARY OVUM:- cells that are to become mature ova have been

multiplying, and by the time that the female is born, all of the egg cells that the ovaries will release during the active reproductive years of the female are already present in the ovaries.

SECONDARY OVUM:- it grows in the ovary until it reaches maturation; it then

breaks loose and is carried into the fallopian tubes. Once in the fallopian tubes, the secondary egg cell is suitable for fertilization by the male sperm cells.

Page 5: Oogenesis and fertilization report
Page 6: Oogenesis and fertilization report

MATURATION OF THE OOCYTES:

Oogonia give rise to oocytes.Before, the birth, oogonia multiply by mitosis. During development of the fetus, many oogonia begin meiosis, but stop in prophase I and are now called PRIMARY OOCYTES. They remain in this state until puberty.

Page 7: Oogenesis and fertilization report

OOGENESIS Just before ovulation the primary oocyte completes meiosis I, creating the secondary oocyte and a nonviable polar body.The secondary oocytes begins meiosis II, but stops at metaphase II.During, ovulation, the secondary oocyte is released from the ovary.The secondary oocyte only completes meiosis II if it is fertilized by a sperm cell. The completion of meiosis II forms a secondary oocyte and a second polar body. Fertilization is complete when the secondary oocyte nucleus and the sperm cell nucleus and the sperm cell nucleus unite, creating a ZYGOTE.

Page 8: Oogenesis and fertilization report

Follicle Development

Page 9: Oogenesis and fertilization report

Primordial Follicle

A primary oocyte surrounded by a single layer of flat cells called granulosa cells.

Page 10: Oogenesis and fertilization report

Primary Follicles

Enlargement of oocyte and a single layer of granulosa cells becomes enlarged and cuboidal.

Page 11: Oogenesis and fertilization report

Secondary Follicle

Forms when a fluid filled vesicles develop among the granulosa cells and well developed theca becomes apparent around the granulosa cells.

Page 12: Oogenesis and fertilization report
Page 13: Oogenesis and fertilization report

If pregnancy occurs, the corpus luteum enlarges in response to a hormones secreted by the placenta called human chorionic gonadotropin hormone (HCG).

If pregnancy does not occur, the corpus luteum lasts for 10-12 days and then begins to degenerate.

Page 14: Oogenesis and fertilization report

FERTILIZATION

Page 15: Oogenesis and fertilization report

FERTILIZATION

Fertilization is the union of sperm cell and oocyte(secondary),

along with their genetic material (chromosomes) to produce a new individual.

Process of Fertilization :

1. After sperm cell ejaculated into vagina, they are transported to the cervix and the body of the uterus to the uterine tubes where the fertilization occurs.

2. Sperms undergo Capacitation.• Capacitation -It makes the sperm cells capable of releasing

the concentrated enzymes contained in the acrosome (a region of the sperm cell head).

3. The enzymes digest a pathway through the cumulus cells and zona pellucida of the secondary oocyte.

Page 16: Oogenesis and fertilization report

FERTILIZATION

4. The enzymes then digest a pathway through the cumulus cells and the zona pellucida of the secondary oocyte.

5. Only one sperm cell attaches to the oocyte cell membrane and enters the oocyte.

6. Subsequently, the secondary oocyte completes the second meiotic division to form 2 cells, each containing 23 chromosomes.

7. After the second meiotic division, the the oocyte nucleus moves to the center of the cell, where it meets the nucleus of the sperm cell.

8. The 23 cells chromosomes from the male then joins with the 23 chromosomes of the females(total 0f 46) forming a ZYGOTE.

Page 17: Oogenesis and fertilization report

4. The zygote divides by mitosis to form 2 cells, which divide to form 4 cells and so on.

5. The mass of cells formed will implant in the uterine wall and will then develop into a new individual.

Page 18: Oogenesis and fertilization report

Many sperm cells come in contact with the cumulus cells of the secondary oocyte, but only one sperm cell will penetrate the oocyte’s cell membrane.

Page 19: Oogenesis and fertilization report

The head of the sperm, carrying the genetic material , enters the oocyte, which completes the second meiotic division.

Page 20: Oogenesis and fertilization report

The two nuclei fuse to form a single nucleus. Fertilization is complete and a zygote results.