Flashcards in A&P Chapter 27 Female Reproductive System Deck (20):
When does the human reproductive system begin developing? When does sexual differentiation begin?
Reproductive development begins in the 4th week of embryonic development and sexual differentiation begins in the 7/8th week of development.
Describe the Broad Ligament
The broad ligament is a MESENTERY which supplies the uterus, ovary and oviduct with support and blood vessels. It has three parts: The MESOMETRIUM, THE MESOVARIUM AND THE MESOSALPINX.
Describe an Ovary
They are located within the pelvis, they are anywhere from 2-5cm lateral to the uterus, they move during different phases of a females cycle. They are approx. 3cmX2cmX1cm
The ovaries are the site of oocyte development and ovulation after puberty.
An ovary has three layers: The Medulla, Cortex and Tunica Albuginea.
All vessels and nerves enter/leave an Ovary at a HILUS.
Describe the Three Layers of an Ovary
The Medulla: Inner layer comprised of Dense Irregular Connective tissue, site of blood vessels.
The Cortex: The Outer region in which oocytes develop.
Tunica Albuginea: The Dense Irregular connective tissue covered by the VISCERAL PERITONEUM which an Oocyte has to rupture through.
What is Oogenesis? Describe oogenesis.
The maturation of an oocyte. It begins a cell with 46 chromosomes divides twice, unevenly, to produce 1 large Oocyte with 23 chromosomes and 2 small Polar Bodies. During Oogenesis the Oocyte is surrounded by Follicular or Granulosa cells.
FOLLICLE STIMULATING HORMONE from the Adenohypophysis is required to stimulate the Follicular cells.
During Oogenesis the FOLLICULAR cells secrete Estrogens which stimulate the inner lining of the Uterus to thick and get ready for pregnancy.
Explain the NEGATIVE FEEDBACK LOOP associated with the Follicular Cells surrounding an Oocyte.
For an Oocyte to be released the FOLLICULAR CELLS must be stimulated by FOLLICLE STIMULATING HORMONE from the Adenohypophysis. Once stimulated the Follicular cells begin producing Estrogens which the Adenohypophysis detects causing it to STOP PRODUCING FOLLICLE STIMULATING HORMONE. This is required so that only a few PRIMORDIAL follicles will begin developing.
Describe the FOUR stages the developing Oocyte and it's surrounding follicle go through before Ovulation.
1. Primordial Follicles: All the oocytes and surrounding follicles are created before birth and stored in the Ovaries cortex remaining dormant until Follicle Stimulating Hormone is introduced by the Adenohypophysis during Puberty. A primordial follicle consists of a Primary Oocyte and a SINGLE layer of FLAT Follicular Cells.
2. Primary Follicles: These develop after puberty with the introduction of FSH. 3-4 Primordial follicles will begin to develop into Primary Follicles. There is NO CHANGE in the Oocyte, the follicle begins development, the follicular cells get larger and begin to secrete Estrogens.
3. Secondary Follicles: 1-2 of the Primary Follicles progress to this stage. The Primary Oocyte gets larger, it finishes it's FIRST DIVISION of meiosis to become a Secondary Oocyte. The Follicle grows larger as the follicular cells divide and produce more estrogens. Spaces inside the follicle begin to develop.
4. Mature or Vesicular Follicle: Most follicles that became a Secondary will make it to this stage. The Follicle becomes VERY large, many follicular cells surround a fluid filled center called the ANTRUM. The Follicle is still secreting large amounts of estrogens. The Secondary Oocyte gets a thick clear membrane layer called the ZONA PELLUCIDIA. The Oocyte is pushed to one side in the follicle and surrounded by a mass of follicular cells called the CUMULUS OOPHORUS. At this point the Oocyte is ready for ovulation.
What is ANTRUM?
The fluid surrounding a SECONDARY OOCYTE which occurs in the Mature/Vesicular Follicle stage of development.
What is the clear membrane that surrounds a Secondary Oocyte in the Mature/Vesicular Stage of development?
The Zona Pellucida.
What stage of Oocyte development does an Oocyte transition from a Primary Oocyte to Secondary Oocyte? What happens to the Oocyte during this phase?
It occurs during the Secondary Follicle stage. The oocyte completes it's 1st division becoming a Secondary Oocyte.
What has to happen for a Follicle to begin developing?
Follicle Stimulating Hormone must be released from the Adenohypophysis.
What are the Four Stages a developing follicle and Oocyte go through before ovulation?
Primordial Follicle, Primary Follicle, Secondary Follicle, and Mature/Vesicular Follicle.
What is Ovulation?
The rupture of a follicle to release an Oocyte.
What triggers Ovulation?
The Adenohypophysis secreting Luteinizing Hormone.
What is the CUMULUS OOPHORUS? What does it turn into?
The group of FOLLICULAR CELLS that surround an oocyte in the Mature/Vesicular stage of oocyte development.
Once the Oocyte is released the Cumulus Oophorus turns into the CORONA RADIATA.
What is the CORONA RADIATA?
The Follicular cells that surround an Oocyte once it has been released from the ovary.
Explain what happens to the EMPTY Follicle in an ovary.
IF LUTEINIZING HORMONE is present the follicle will change into a CORPUS LUTEUM and begin secreting PROGESTERONE.
What does the CORPUS LUTEUM become after it stops producing Progesterone?
A CORPUS ALBICANS.
What has to occur for the CORPUS LUTEUM to continue producing Progesterone for months?
Fertilization and Implantation of an oocyte. If this doesn't occur then the Corpus Luteum degenerates to form a Corpus Albicans.