Week 14 Female Reproductive System

Difference between how male and female reproductive systems provide gametes

females produce 1 gamete per month and retains and nurtures zygote

males disseminates large quantities of gametes

inguinal canal

passageway in anterior abdominal wall
in males, contains spermatic cords
in females, contains round ligaments

how much sperm does a male produce per day?

about 0.5 billion

functions of FRS (female reproductive system)

produce sex hormones and functional gametes
protects and supports developing embryo
nourishes newborn infant

gonads

organs that produce gametes and hormones
ovaries/testes

perineal structures

aka external genitalia

accessory glands of reproductive system

glands that secrete fluid into ducts

What makes up the vulva (external female genitalia)?

mons pubis, labia majora/minora, clitoris covered by prepuce, hymen, and Bartholin’s glands

labia majora

protects and encloses the other external reproductive organs
contains sebaceous and sweat glands
covered w hair right after puberty

clitoris

both the labia minora encounter at the clitoris
a small, delicate protrusion
sensitive to stimulus and can turn erect

what structure of the FRS is homologous to the penis in the MRS?

clitoris

hymen

membrane that covers the entrance to vagina

Bartholin’s glands

located near the vaginal opening
secrete mucus for lubrication

prepuce

skin fold that covers clitoris

vagina

elastic, muscular, highly distensible tube
lined with mucosa that houses healthy microorganisms to fight infection

bacterial flora in vagina

secretes lactic acid to maintain the acidic pH of vagina which protects against infection

what is the most notable microorganism that helps maintain vaginal acidic pH?

lactobacillus

cervix

“neck”
part of uterus that projects into vagina

fornix

a shallow recess surrounding cervical protrusion

embryo

weeks 1-8

fetus

weeks 9 thru delivery

position of uterus

normally anteflexed; can be retroflexed in some people

what ligaments support uterus

broad ligament, uterosacral ligaments, round ligaments, and lateral/cardinal ligaments

regions of uterus (and where they are) - superior to inferior

fundus (rounded part on top), body/corpus (largest part, ends at isthmus), and cervix (isthmus to vagina)

broad ligament

encloses uterus, fallopian tubes, and ovaries
basically a continuation of the parietal peritoneum

Uterosacral ligaments

prevent inferior-anterior movement of uterus

round ligaments

extend through inguinal canal
restrict posterior movement

lateral/cardinal ligaments (function—not connection)

prevent inferior movement

cervical canal

extends into uterine cavity at internal os. and opens into vagina at external os.

Uterine wall structure

Perimetrium - outer serous membrane (epithelial cells)

Myometrium - thick, middle smooth muscle layer. contracts during labor to push fetus out

Endometrium - mucosa layer (lamina propria + epithelium). contains uterine glands

uterine glands (function, location, when they are most active)

In endometrium. Open onto endometrial surface, extend deep into lamina propria. secrete substances that help nourish embryo and maintain uterine lining. most active during secretory phase

Myometrium structure

Outermost layer is longitudinal
Middle layer is oblique
Innermost layer is circular

2 zones or layers of endometrium

stratum functionalis (functional zone)
stratum basalis (basilar zone)

functional zone of endometrium

undergoes cyclical changes
contains most uterine glands
sheds during menstruation

basilar zone of endometrium

attaches endometrium to myometrium
regenerates the functional layer
remains relatively constant (in thickness)

ovaries (function—what ALL do they produce)

produce oocytes, female sex hormones, and inhibin

what are the female sex hormones

estrogen and progesterone

inhibin

hormone that regulates the negative feedback loop of FSH by signaling the pituitary to slow/stop production of FSH (does not tell HT to suppress GnRH!)
does not affect LH

luteolysis

the degeneration of the corpus luteum

when is progesterone highest?

luteal/secretory phase

when is estrogen highest (+ a side note)

mid cycle (~days 11-16), but also goes up mid-luteal/secretory phase. however, the follicular phase is when it is the "dominant hormone" since it is the one driving most of the changes at that point--even though its not when it's at its highest.

when Dr. Serrano says “menstrual cycle,” what is she most likely referring to?

uterine cycle

when is FSH highest?

pretty high throughout follicular phase but peaks at ovulation

what structures support ovaries

mesovarium (small portion of broad ligament), ovarian ligament, suspensory ligament

mesovarium

stabilizes ovary position

ovarian ligament

connects ovary to uterus

suspensory ligament

connects ovary to pelvic wall
contains blood vessels that enter at the ovarian hilum

ovarian hilum

point of entry for blood vessels, nerves, and lymphatic vessels into the ovary

oogenesis

ovum production

when does oogenesis occur (and when it ends)

begins before birth, accelerates at puberty, and ends at menopause

what triggers the start of ovarian cycle at puberty?

rising FSH levels

Follicle-Stimulating Hormone (FSH)

stimulates growth and maturation of ovarian follicles

Luteinizing hormone

Triggers ovulation and promotes formation of corpus luteum

How many primary oocytes (in fetus) are present at 20 weeks of gestational age?

about 7 million

how many primary oocytes are present at birth

about 1-2 million

how many primary oocytes are present at puberty? why?

about 400,000
due to atresia (degeneration of follicles)

at what stage is oogenesis paused in from birth till puberty (and what cells)

primary oocytes
prophase I of meiosis

After puberty, what happens to the primary oocytes that are present?

Each month, FSH stimulates some primary oocytes to continue meiosis. One of them becomes a secondary oocyte and is paused in metaphase II (unless fertilized)

how is FRS different from MRS in regards to the rate of development of gametes? how does this affect female fertility?

Oocytogenesis (creation of primary oocytes from oogonia) is complete before birth, whereas spermatocytogenesis continues throughout life
This is why female fertility declines throughout life because you’re using up a limited supply of POs

steps of oogenesis

Oogonia undergo mitosis, making one PO and the other stays a stem cell.
Meiosis I is begun in POs and stuck in prophase I until puberty, when meiosis I is complete and POs becomes a haploid SO + 1st polar body (may split into 2 bodies).
SO begins meiosis II in tertiary follicle (ovulated during metaphase), and meiosis II is completed if fertilization occurs. This creates an ovum and 2nd polar body

In order of development, what are the female gamete stages?

oogonium, primary oocyte, secondary oocyte + polar body(ies), ovum + polar body (if fertilized)

what does oogenesis produce? why?

1 ovum and 2-3 nonfunctional polar bodies due to uneven cytoplasmic division

what cell does the ovary release at ovulation?

secondary oocyte

what happens during folliculogenesis? (name the specific starting and end products)

follicle development
primordial follicles → preovulatory (Graafian) follicles

What are follicles in the ovaries? What do they do?

little sacs in ovaries that contain one immature egg cell (oocyte)
they hold and support the developing egg
as they mature, they produce hormones and eventually burst to release the egg (ovulation)

granulosa cells of ovary

supporting cells that grow around the oocyte inside a developing follicle
produce sex hormones and inhibin

oogonium (plural: oogonia) + what it becomes

the stem cell of female gametes
becomes primary oocyte

is primary oocyte diploid or haploid?

diploid; not haploid until secondary oocyte

ovum

the product of fertilization of a secondary oocyte

what do people usually refer to as the “egg”? (like what specific cell)

secondary oocyte that gets released

how does a primary oocyte become a secondary oocyte?

by completing meiosis I

steps of folliculogenesis

Primary follicle (layer of granulosa cells surrounding primary oocyte) forms.
Secondary follicle (primary oocyte, granulosa layers, and follicular fluid) forms.
Tertiary follicle forms; primary oocyte becomes secondary oocyte + polar body; the SO floats in the antrum of TF).
Ovulation (tertiary follicle ruptures and releases SO)
Corpus luteum (remains of TF) forms, produces progesterone
Corpus albicans (scar tissue that the CL turns into if no fertilization occurs)

when does the corpus luteum degenerate into the corpus albicans?

About 12 days after ovulation

do newborn females have follicles? if so, what kind/stage?

yes, they have primordial follicles (that continue into primary follicles at puberty)

zona pellucida

a zone of the ovarian follicles
glycoprotein layer with microvilli around the oocyte (innermost)

Corona radiata

A layer of granulosa cells surrounding the zona pellucida in a follicle.

Thecal cells

Produce sex hormones along with granulosa cells but not inhibin, surround follicle

antrum

fluid-filled central cavity of follicle surrounded by granulosa cells

layers of the ovarian follicle, inner to outermost

oocyte
zona pellucida
corona radiata (innermost granulosa cells)
antrum
rest of the granulosa cells
thecal cells

order of changes in ovary starting at menstruation (assuming no fertilization occurs)

menstruation, developing follicle, mature follicle, ovulation, corpus luteum, deterioration of corpus luteum

2 other names for uterine tubes

fallopian tubes or oviducts

GnRH (gonadotrophic releasing hormone)

hormone released by hypothalamus telling anterior pituitary to release LH and FSH

hormonal control/regulation in follicular phase of ovarian cycle

GnRH released, LH, FSH released.

FSH and LH stimulate several follicles to grow. early in this phase, slightly increasing estradiol [type of estrogen] levels from small follicles inhibits GnRH, LH, and FSH (negative feedback), causing arterial constriction leading to menstruation.

Later in the phase, higher estradiol stimulates GnRH, causing LH surge (positive feedback)

hormonal control/regulation in ovulation “phase” of ovarian cycle

high estradiol causes LH surge (positive feedback) and thickening of uterine lining

hormonal control/regulation in luteal phase of ovarian cycle

LH causes corpus luteum to form. CL makes progesterone and a little estradiol, which suppress GnRH (negative feedback) and maintain uterine lining

Laterally to medially, what are the segments of the uterine tubes?

Infundibulum, ampulla, isthmus

Infundibulum of uterine tubes

funnel
lined with cilia

Ampulla of uterine tubes

middle, widest segment
smooth muscle layer in wall is becoming thicker approaching uterus

in which section of the uterine tubes does fertilization occur?

ampulla

how is SO moved through the uterine tubes (and what stimulates it)?

ciliary mvmt and peristalsis (stimulated by estrogen and hypogastric plexus nerves)

epithelium lining uterine tube

ciliated with scattered mucin-secreting cells

do uterine tubes help nourish/support sperm and embryo?

yes, they provide nutrients (lipids, glycogen) for sperm and embryo

how long does transport from the ovary to the uterus take?

3-4 days

When is the fertilization window? What does this overlap with?

12-24 hours after ovulation
this is the SO’s lifespan

what happens to unfertilized oocytes?

they degenerate and are expelled during menstruation

uterine cycle

repeating changes in the endometrium
about 28 days

phases of uterine (menstrual) cycle

menses, proliferative phase, secretory phase

how much blood is lost during menstruation?

35-50mL

what is menses caused by (not what hormones, but what event or process)?

The constriction of spiral arteries bc it reduces blood flow, oxygen, and nutrients and weakened arterial walls rupture

skip

skip