The Female Reproductive System

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functions of the female reproductive system

- Production of female gametes (oocytes)
- Synthesis of female sex hormones
- Reception of sperm cells from the male
- Nurturing the developing embryo

parts of the Female Reproductive Anatomy

- Uterine (fallopian) tube
- ampulla
- uterus
- vagina
- ovary
- uterine wall
- endometrium
- cervix

ovaries

primary female reproductive organs

Accessory ducts

include uterine tubes, uterus, and vagina

ovaries function

- Make female gametes
- Secrete female sex hormones (estrogen and progesterone)

Oogenesis

Production of female sex cells by meiosis

step 1 of oogenesis

In the fetal period, oogonia (2n ovarian stem cells) multiply by mitosis and store nutrients

step 2 of oogenesis

Primary oocytes begin meiosis but stall in prophase I (2M make it)

step 3 of oogenesis

At puberty, in a cycled manner, activated primary oocytes divide, each produces two haploid cells
o The first polar body (had to be small to make the ovum as large as possible)
o The secondary oocyte
o happens just before stops in metaphase II

step 4 of oogenesis

The secondary oocyte arrests in metaphase II and is ovulated

step 5 of oogenesis

If penetrated by sperm, the second oocyte completes meiosis II, yielding one large ovum and a tiny second polar body
o 23 chromosomes & 23 chromatids
o upon fertilization, meiosis will be completed; when fertilized it will become a zygote

2 monthly cycles

[in preparation for fertilization]
- Ovarian Cycle
- Uterine (Menstrual) Cycle

ovarian cycle

• Monthly series of events associated with the maturation of an egg (oocyte)
o Follicular phase and Luteal phase
• make sure that there is only 1 egg, that the uterus is ready for the embryo

Uterine (Menstrual) Cycle

• Monthly series of events associated with the uterine wall in response to ovarian hormones in the blood
• dependent on the ovarian cycle, happens in response to hormones secreted in the ovaries

follicular phase

- (~ 14 days) first phase of the ovarian cycle
- follicle (an oocyte and its surroudning cells) enlarges and matures.
- phase is under the control of FSH from the anterior pituitary,
- follicle secretes estrogen during this time period.

step 1 of the ovarian cycle

[follicular phase]
- Before puberty: primordial follicle (oocyte covered with a _____ cells)

1) At puberty, the oocyte is surrounded by a small, primary follicle
• signal causes primordial follicle → primary follicle
• grandulosa cells: nourishing
• osteocyte: sends messages to grandulosa
• between the grandulosa cells and the osteocyte you will have cytoplasmic ridges
• talking chemically to each other

step 2-5 of the ovarian cycle

[follicular phase]
2-5) Follicle enlarges. A zona pellucida and a theca layer are formed
• zona pellucida: protects the oocyte so that only one sperm can empty
• as grandulosa cells get bigger (proliferate) → oocyte gets bigger
• formation of the theca cells
• Step 5.5: accumulation of fluid

step 6 of the ovarian cycle

[follicular phase]
Primary follicle becomes a secondary, and then a mature follicle, with a fluid filled space
• follicle is still not mature (primary oocyte)
• just prior to ovulation primary oocyte completes 1st meiotic stage and stops at metaphase II

step 7 of the ovarian cycle

Ovulation takes place

luteal phase

- The third phase of the ovarian cycle
- corpus luteum is formed from the remnants of the follicle that has ovulated its oocyte.
- The corpus luteum secretes progestrone and estrogen during this time period, which
- typically lasts from day 15 to day 28 of the menstrual cycle.
- Formation of the corpul luteum is triggered by the same LH surge that triggers ovulation,
- however in the absence of LH (levels quickly decline after the surge) the corpus luteum begins to degenerate.

step 8 of the ovarian cycle

[luteal phase]
- After ovulation, the ruptured follicle collapses, granulosa cells enlarge, and along with internal thecal cells, form the corpus luteum
• The corpus luteum is secreting estrogen and progesterone, which are essential for implantation of the embryo
• stops a new cycle from starting

step 9 of the ovarian cycle

[luteal phase]
- The corpus luteum will survive only if fertilization occurs (24h after ovulation). If not, it will start degrading

hormonal regulation (pic)

At puberty, GnRH (Gonatropin releasing hormone) is released; FSH and LH are released by the pituitary, which act on the ovaries

step 1 of hormonal regulation

Day 1 - GnRH stimulates the release of FSH and LH

step 2 of hormonal regulation

FSH (on granulosa) and LH (on theca) stimulate follicle growth and maturation, and low-level estrogen release

step 3 of hormonal regulation

Rising estrogen levels assist in maturation and inhibit the release of FSH and LH

step 4/5 of hormonal regulation

Estrogen levels increase and high estrogen levels have a positive feedback effect on the pituitary, causing a sudden surge of LH (5)

step 6 of hormonal regulation

The LH spike [Also sudden surge of FSH but affect (right now) is minor]
o stimulates the primary oocyte to complete meiosis I
o triggers ovulation
o transforms the ruptured follicle into a corpus luteum, which produces inhibin, progesterone, and estrogen (7-8)

LH, FSH and estrogen

[pituitary]
- allows for development of the follicle, maturation of the oocyte and ovulation
- The last stage, forming the corpus luteum, provides the negative feedback that will prevent any more ovulations in this cycle
- need negative feedback because without it more follicles would be formed and eggs would be released!

corpus luteum

prepares the uterus for the coming embryo (if fertilization takes place)

endometrium

• The mucosal lining of the uterine cavity
• The site of implantation : anchoring of the embryo and formation of the placenta
• Degeneration and regeneration (stretch and relaxation spasms) of spiral arteries causes the tissue to shed during menstruation

parts of the uterine (Menstrual) Cycle

- Menstrual phase Days (1-5)
- Proliferative phase (6-14)
- Secretory phase (15-28)

menstrual phase

uterus sheds most of the endometrium, accompanied by bleeding (menses)

Proliferative phase

Estrogen secreted from the ovarian follicles stimulates endometrium recovery

Secretory phase

Progesterone stimulates the endometrium to prepare for implantation of the embryo

progesterone

- secreted from the corpus luteum
- No fertilization: corpus luteum degenerates, no progesterone and estrogen, back to menstrual phase
- Fertilization: embryo secretes hCG (LH-like in effect), corpus luteum survives, continuing pregnancy
• HcG tells you if you are pregnant or not

female sexual response

main pleasure organ is the hypothalamus - center for sex drive (male and female)
• Prompted by androgens secreted from the adrenal cortex

effect of the female sexual response

• quite similar to males!! No ejaculation, but similar mechanisms of erection
• The clitoris, vaginal mucosa, and breasts engorge with blood
• Activity of vestibular glands lubricates the vestibule and facilitates entry of the penis
• Orgasm - accompanied by muscle tension, increase in pulse rate and blood pressure, and rhythmical contractions of the uterus

uterine contraction

• Prostaglandins in the semen (seminal vesicles - also produce fructose)
• Oxytocin from the posterior pituitary of the female

cervical mucus

• Estrogen will cause it to thin
• Progesterone will make it viscous, forming a cervical plug
o after fertilization - 24 hour period
o sperm must come before ovulation but not too far up
• Vagina is acidic, has a cervical plug to prevent sperm
• Sperm comes with alkaline semen (prostaglandins - seminal vesicles)

entopic pregnancies

fertilization in the fallopian tube

cervix

- The opening to the uterus
- typically plugged with a sticky acidic mucus during non-fertile times
- (to form a barrier against the entry of pathogens)
- during ovulation the mucus becomes more watery and alkaline to facilitate sperm entry.

uterine wall

muscle layers that stretch to accommodate the developing baby, contracting during childbirth to deliver the baby

ovary

one of two glands located on each side of the pelvic cavity that produce ova and female sex hormones

vagina

part of the female reproductive system that leads from the uterus to the outside of the body; functions as the birth canal and the passageway for menstrual flow

uterus

the hollow muscular organ of the female reproductive system in which a fertilized egg develops

ampulla

The outer two-thirds of the fallopian tube; fertilization of the ovum by a spermatozoon usually occurs here.

Uterine (fallopian) tube

- where fertilization occurs (can result in ectopic pregnancy),
- Extends from the ovary to the uterus, it serves as a conduit for ova and spermatozoa.

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