The Female Reproductive System: Hormonal Packet #31

PowerPoint® Lecture Slides prepared by Ryan Barrow Blanche Ely High School

C H A P T E R 27

• The ovaries – pp104 – 1042 • The endometrium – p. 1044 • The mammary glands – pp. 1047 – 1048 • Physiology of the female reproductive system – pp. 1049 – 1058

Front View Side View

1. Breast – mammary glands 2. Ovaries and follicle development

• Modified sweat glands consisting of 15–25 lobes • Areola: pigmented skin surrounding the nipple • Suspensory ligaments: attach the breast to underlying muscle • Lobules within lobes contain glandular alveoli that produce milk

• Milk  lactiferous ducts  lactiferous sinuses  open to the outside at the nipple

Copyright © 2010 Pearson Education, Inc. First rib Skin (cut) Pectoralis major muscle Suspensory ligament Adipose tissue Lobe Areola Nipple Opening of lactiferous duct Lactiferous sinus Lactiferous duct Lobule containing alveoli Hypodermis (superficial fascia) Intercostal muscles (a) (b)

• 70% of women with breast cancer have no known risk factors • Early detection via self- examination and mammography • Treatment depends upon the characteristics of the lesion: • Radiation, chemotherapy, and surgery followed by irradiation and chemotherapy

Malignancy

(b) Film of normal breast (c) Film of breast with tumor

• Usually arises from the epithelial cells of small ducts • Risk factors include: • Early onset of menstruation and late menopause • No pregnancies or first pregnancy late in life • Family history of breast cancer • 10% are due to hereditary defects, including mutations to the genes BRCA1 and BRCA2

• Production of female gametes • Begins in the fetal period • Oogonia (2n ovarian stem cells) multiply by mitosis and store nutrients • Primary oocytes develop in primordial follicles • Primary oocytes begin meiosis but stall in prophase I

• Follicle • Immature egg (oocyte) surrounded by • Follicle cells (one cell layer thick) • Granulosa cells (when more than one layer is present)

• Several stages of development • Primordial follicle: squamouslike follicle cells + oocyte • Primary follicle: cuboidal or columnar follicle cells + oocyte • Secondary follicle: two or more layers of granulosa cells + oocyte • Late secondary follicle: contains fluid-filled space between granulosa cells; coalesces to form a central antrum

• Vesicular (Graafian) follicle • Fluid-filled antrum forms; follicle bulges from ovary surface • Ovulation • Ejection of the oocyte from the ripening follicle • Corpus luteum develops from ruptured follicle after ovulation

Copyright © 2010 Pearson Education, Inc. Tunica albuginea Oocyte Granulosa cells Late secondary follicle Degenerating corpus Cortex Mesovarium and luteum (corpus blood vessels albicans) Germinal Vesicular epithelium (Graafian) Primary follicle follicles Antrum Oocyte

Ovarian Zona ligament pellucida Theca Medulla folliculi Ovulated oocyte Corpus luteum Developing Corona corpus luteum radiata (a) Diagrammatic view of an ovary sectioned to reveal the follicles in its interior

• Each month after puberty, a few primary oocytes are activated • One is selected each month to resume meiosis I • Result is two haploid cells • Secondary oocyte • First polar body

• The secondary oocyte arrests in metaphase II and is ovulated • If penetrated by sperm the second oocyte completes meiosis II, yielding • Ovum (the functional gamete) • Second polar body

Primary oocyte Primordial follicle Growth

Infancy and Primary oocyte Primordial follicle childhood (arrested in prophase I; (ovary inactive) present at birth)

Each month from puberty to Primary follicle menopause Primary oocyte (still arrested in prophase I) Secondary follicle

Spindle Vesicular (Graafian) follicle

Meiosis I (completed by one primary oocyte each month in response to LH surge) Secondary oocyte First polar body (arrested in metaphase II) Ovulation Sperm Meiosis II of polar Ovulated secondary body (may or may oocyte not occur) Meiosis II In absence of completed (only if fertilization, ruptured sperm follicle becomes a Polar bodies penetration corpus luteum and Second Ovum (all polar bodies occurs) Degenating ultimately degenerates. polar body degenerate) corpus luteum

• Monthly series of events associated with the maturation of an egg • Two consecutive phases (in a 28-day cycle) • Follicular phase: period of follicle growth (days 1–14) • Ovulation occurs midcycle • Luteal phase: period of corpus luteum activity (days 14–28)

• Primordial follicle becomes primary follicle 1. The primordial follicle is activated • Squamouslike cells become cuboidal 2. Follicle enlarges to become a primary (1) follicle

3. Primary follicle becomes a secondary follicle • Stratified epithelium (granulosa cells) forms around oocyte • Granulosa cells and oocyte guide one another’s development

4. Secondary follicle becomes a late secondary follicle • Connective tissue (theca folliculi) and granulosa cells cooperate to produce estrogens • Zona pellucida forms around the oocyte • Fluid begins to accumulate

Copyright © 2010 Pearson Education, Inc. Figure 27.18 (3 of 7) Theca folliculi 3 4 2 1 Primary oocyte Zona pellucida Antrum Secondary 5 oocyte 8 6 Secondary oocyte 4 Late secondary 7 Corona radiata follicle

5. Late secondary follicle becomes a vesicular follicle • Antrum forms and expands to isolate the oocyte with its corona radiata on a stalk • Vesicular follicle bulges from the external surface of the ovary • The primary oocyte completes meiosis I

• Ovary wall ruptures and expels the secondary oocyte with its corona radiata • Mittelschmerz: twinge of pain sometimes felt at ovulation • 1–2% of ovulations release more than one secondary oocyte, which, if fertilized, results in fraternal twins

Copyright © 2010 Pearson Education, Inc. Theca folliculi 3 4 2 1 Primary oocyte Zona pellucida Antrum Secondary 5 oocyte 5 Mature vesicular 8 6 follicle carries out Secondary oocyte meiosis I; ready to 7 Corona radiata be ovulated

Copyright © 2010 Pearson Education, Inc. Figure 27.18 (5 of 7) Theca folliculi 3 4 2 1 Primary oocyte Zona pellucida Antrum Secondary 5 oocyte 6 Follicle ruptures; 8 6 Secondary oocyte secondary oocyte 7 Corona radiata ovulated

• Ruptured follicle collapses • Granulosa cells and internal thecal cells form corpus luteum • Corpus luteum secretes progesterone and estrogen

• If no pregnancy, the corpus luteum degenerates into a corpus albicans in 10 days • If pregnancy occurs, corpus luteum produces hormones until the placenta takes over at about 3 months

Copyright © 2010 Pearson Education, Inc. Theca folliculi 3 4 2 1 Primary oocyte Zona pellucida Antrum Secondary 5 oocyte 7 Corpus luteum 8 6 Secondary oocyte (forms from 7 Corona radiata ruptured follicle)

• During childhood, ovaries grow and secrete small amounts of estrogens that inhibit the hypothalamic release of GnRH • As puberty nears, GnRH is released; FSH and LH are released by the pituitary, and act on the ovaries • These events continue until an adult cyclic pattern is achieved and menarche occurs

• During childhood, until puberty • Ovaries secrete small amounts of estrogens • Estrogen inhibits release of GnRH

• At puberty • Leptin from adipose tissue decreases the estrogen inhibition • GnRH, FSH, and LH are released • In about four years, an adult cyclic pattern is achieved and menarche occurs

Copyright © 2010 Pearson Education, Inc. Hormonal Interactions During a 28-Day Ovarian Cycle • Day 1: GnRH  release of FSH and LH • FSH and LH  growth of several follicles, and estrogen release •  estrogen levels • Inhibit the release of FSH and LH • Stimulate synthesis and storage of FSH and LH • Enhance further estrogen output

Copyright © 2010 Pearson Education, Inc. Hormonal Interactions During a 28-Day Ovarian Cycle • Estrogen output by the vesicular follicle increases • High estrogen levels have a positive feedback effect on the pituitary at midcycle • Sudden LH surge at day 14

Copyright © 2010 Pearson Education, Inc. Hormonal Interactions During a 28-Day Ovarian Cycle • Effects of LH surge • Completion of meiosis I (secondary oocyte continues on to metaphase II) • Triggers ovulation • Transforms ruptured follicle into corpus luteum

Copyright © 2010 Pearson Education, Inc. Hormonal Interactions During a 28-Day Ovarian Cycle • Functions of corpus luteum • Produces inhibin, progesterone, and estrogen • These hormones inhibit FSH and LH release • Declining LH and FSH ends luteal activity and inhibits follicle development

Copyright © 2010 Pearson Education, Inc. Hormonal Interactions During a 28-Day Ovarian Cycle • Days 26–28: corpus luteum degenerates and ovarian hormone levels drop sharply • Ends the blockade of FSH and LH • The cycle starts anew

GnRH 4 Positive 8 Travels via feedback exerted portal blood by large in estrogen 1 output.

Anterior pituitary 1 5 Progesterone LH surge Estrogen Inhibin FSH LH Ruptured 6 2 2 follicle 8

3 Slightly elevated 7 estrogen Thecal and rising cells inhibin levels. Granulosa Androgens Corpus luteum cells Mature follicle Ovulated Convert secondary Inhibin androgens to 2 oocyte estrogens Late follicular and Early and midfollicular phases luteal phases

FSH

(a) Fluctuation of gonadotropin levels: Fluctuating levels of pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) in the blood regulate the events of the ovarian cycle.

Follicular Ovulation Luteal phase (Day 14) phase (b) Ovarian cycle: Structural changes in the ovarian follicles during the ovarian cycle are correlated with (d) changes in the endometrium of the uterus during the uterine cycle.

• Cyclic changes in endometrium in response to ovarian hormones • Three phases 1. Days 1–5: menstrual phase 2. Days 6–14: proliferative (preovulatory) phase 3. Days 15–28: secretory (postovulatory) phase (constant 14-day length)

• Menstrual phase • Ovarian hormones are at their lowest levels • Gonadotropins are beginning to rise • Stratum functionalis is shed and the menstrual flow occurs

• Proliferative phase • Estrogen levels prompt generation of new functional layer and increased synthesis of progesterone receptors in endometrium • Glands enlarge and spiral arteries increase in number

• Secretory phase • Progesterone levels prompt • Further development of endometrium • Glandular secretion of glycogen • Formation of the cervical mucus plug

Progesterone

(c) Fluctuation of ovarian hormone levels: Fluctuating levels of ovarian hormones (estrogens and progesterone) cause the endometrial changes of the uterine cycle. The high estrogen levels are also responsible for the LH/FSH surge in (a).

• Stratum functionalis (functional layer) • Changes in response to ovarian hormone cycles • Is shed during menstruation • Stratum basalis (basal layer) • Forms new functionalis after menstruation • Unresponsive to ovarian hormones

Straight artery

Endometrial vein Smooth muscle fibers Radial artery

Arcuate artery Uterine artery (b)

Straight artery

Endometrial vein Smooth muscle fibers Radial artery

Arcuate artery Uterine artery (b)

Menstrual flow Functional layer Basal layer Days Menstrual Proliferative Secretory phase phase phase (d) The three phases of the uterine cycle: • Menstrual: Shedding of the functional layer of the endometrium. • Proliferative: Rebuilding of the functional layer of the endometrium. • Secretory: Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo. Both the menstrual and proliferative phases occur before ovulation, and together they correspond to the follicular phase of the ovarian cycle. The secretory phase corresponds in time to the luteal phase of the ovarian cycle.

• If fertilization does not occur • Corpus luteum degenerates • Progesterone levels fall • Spiral arteries kink and spasm • Endometrial cells begin to die • Spiral arteries constrict again, then relax and open wide • Rush of blood fragments weakened capillary beds and the functional layer sloughs

• Promote oogenesis and follicle growth in the ovary • Exert anabolic effects on the female reproductive tract • Support the rapid but short-lived growth spurt at puberty

• Induce secondary sex characteristics • Growth of the breasts • Increased deposit of subcutaneous fat (hips and breasts) • Widening and lightening of the pelvis

• Metabolic effects • Maintain low total blood cholesterol and high HDL levels • Facilitates calcium uptake

• Progesterone works with estrogen to establish and regulate the uterine cycle • Effects of placental progesterone during pregnancy • Inhibits uterine motility • Helps prepare the breasts for lactation

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