ZOOL-1072 Human Anatomy and Physiology

UNIT 6 REPRODUCTION AND DEVELOPMENT PART 1 THE REPRODUCTIVE SYSTEMS ZOOL-1072 Human Anatomy and Physiology FEMALE REPRODUCTIVE SYSTEM Introduction Purpose of sexual reproduction Fertilization Gynecology

Urology Diagnosis and treatment of female reproductive diseases Urinary system and issues with male reproductive system Andrology Male reproductive disorders Female reproductive system Gonads ovaries Uterine (fallopian) tubes or

oviducts Uterus Vagina External organs vulva or pudendum Mammary glands Figure 28.11 Female organs of reproduction and surrounding structures Figure 28.11 Female organs of reproduction and surrounding structures Ovaries Paired glands homologous to the testes Produce Gametes

secondary oocytes that develop into mature ova (eggs) after fertilization Hormones including progesterone, estrogens, inhibin and relaxin Series of ligaments hold ovaries in place Broad ligament part of parietal peritoneum Ovarian ligament anchors ovaries to uterus Suspensory ligament attaches ovaries to pelvic wall Figure 28.12 Relative positions of the ovaries, the uterus, and supporting ligaments Figure 28.13 Histology of the ovary

Histology of ovary Germinal epithelium covers surface of ovary Tunica albuginea Ovarian cortex Does not give rise to ova cells that arise form yolk sac and migrate to ovaries do

Contains ovarian follicles and stromal cells Ovarian medulla Contains blood vessels, lymphatic vessels, and nerves Ovarian Follicles Ovarian follicles in cortex; consist of oocytes in various stages of development

Surrounding cells nourish developing oocyte and secrete estrogens as follicle grows Mature (graafian) follicle large, fluid-filled follicle ready to expel secondary oocyte during ovulation Corpus luteum remnants of mature follicle after ovulation Produces progesterone, estrogens, relaxin and inhibin until it degenerates into corpus albicans Figure 28.13 Histology of the ovary Oogenesis and follicular development

Oogenesis begins before females are born Essentially same steps of meiosis as spermatogenesis During early fetal development, primordial (primitive) germ cells migrate to ovaries Germ cells then differentiate into oogonia diploid (2n) stem cells Before birth, most germ cells degenerate atresia A few develop into primary oocytes that enter meiosis I during fetal development

Each covered by single layer of flat follicular cells primordial follicle About 200,000 to 2,000,000 at birth, 40,000 remain at puberty, and around 400 will mature during a lifetime Follicular Development Primordial Follicles Oogenesis begins in females before they are born Oogonium Primary oocyte (2n) Primary oocyte enters and remains in prophase I of meiosis

Each primary oocyte is surrounded by follicular and stromal cells the primordial follicle Follicular Development Primary Follicles Each month after puberty, several primordial follicles develop into primary follicles Under control of FSH and LH

Primary oocyte grows in size and forms zona pellucida around itself Follicular cells form granulosa cells Stromal cells form theca folliculi Follicular Development Secondary Follicles Primary follicles develop into secondary follicles

Theca interna secretes estrogen Theca externa structural Granulosa cells secrete follicular fluid in antrum Innermost granulosa layer attaches to zona pellucida forming corona radiata Follicular Development Mature Follicles Secondary follicle becomes mature follicle

Primary oocyte completes meiosis I just before ovulation First polar body is discarded Secondary oocyte begins meiosis II and awaits ovulation Follicular Development Ovulation Secondary oocyte expelled from ovary at ovulation If fertilized by sperm, then secondary oocyte completes meiosis II

Second polar body is discarded Ovum unites with sperm to form a zygote (2n) Figure 28.15 Oogenesis Tuesday Quickly review follicular development and clarify a few terms from yesterday. Continue with uterine tube, uterus, mucus,

vagina, vulva, perineum, mammary glands Tomorrow start the female reproductive cycle Figure 28.13 Histology of the ovary Germinal Epithelium Tunica Albuginea Ovarian Cortex Follicles

Ovarian Medulla Vessels Review of Ovarian Follicles Primordial, Primary and Secondary follicles Contain oocytes in various stages of development Surrounded by nourishing / hormone releasing cells: One layer = follicular cells Multiple layers = granulosa cells

Mature (graafian) follicle External stromal cells synthesize ECM + collagen Large, fluid-filled follicle Ready to expel secondary oocyte during ovulation Corpus luteum (yellow body) remnants of mature follicle Produces progesterone, estrogens, relaxin and inhibin until it degenerates into corpus albicans (white body)

Outermost granulosa cells sit on basement membrane (BM) Stromal cells become organized = theca folliculi Zona pellucida (ZP) clear glycoprotein layer dev.

between primary oocyte and granulosa cells as follicle grows Antrum cavity fills with fluid secreted by granulosa cells Innermost granulosa cells becomes firmly attached to ZP

= corona radiate Oogenesis Review Happens in ovaries each month. The secondary oocyte took several months to mature. If no fertilization occurs, ovulated

cell degenerates. If sperm present meiosis II resumes and a zygote is hopefully formed. Uterine (fallopian) tubes or oviducts Provide a route for sperm to reach an ovum Transport secondary oocytes and fertilized ova from ovaries to uterus Parts (from ovary to uterus)

Fimbriae catches ovum Infundibulum Ampulla where fertilization often takes place Isthmus joins to uterus Figure 28.16 Relationship of the uterine tubes to the ovaries, uterus, and associated structures Histology of the Fallopian Tubes Mucosa

Epithelium Ciliated simple columnar cells conveyor belt Peg cells Fluid = calcium, sodium, chloride, glucose, proteins, bicarbonates, and lactic acid Lamina Propria Areolar CT Folds and papillae

Muscularis Inner circular smooth muscle Outer longitudinal smooth Peristaltic contractions Serosa Fertilization Fertilization up to 24 hours after ovulation

Nuclei of sperm and ovum unite some hours after Usually in ampulla best enviro Zygote (or oocyte) arrives in uterus 6-7 days after ovulation Fertilization in the peritoneal cavity Fimbriae didnt sweep ooctye into lumen of tubes Missing fallopian tube on ovulation side / hormonal imbalance. Usually still results in an intrauterine pregnancy (meaning mechanisms other than just the action of the fimbriae act on transporting the oocytes)

Sometimes results in an ectopic pregnancy (implantation outside the uterus) Uterus Size and shape of inverted pear Nonpregnant / recently pregnany /

menopause Functions: Pathway for spermatozoa Site of implantation of fertilized ovum Fetal development during pregnancy Labor Source of menstruation (if implantation absent) Uterus

Anatomy Fundus Body Uterine cavity Isthmus Cervix (opens into vagina) Cervical

canal Normally anteflexed anterior & superior over bladder Ligaments maintain position broad and round Figure 28.16 Relationship of the uterine tubes to the ovaries, uterus, and associated structures Figure 28.12 Relative positions of the ovaries, the uterus, and supporting ligaments Uterus Histology 3 layers

Perimetrium (serosa) outer layer Simple squamous and areolar CT Laterally becomes broad ligament Myometrium 3 layers of smooth muscle Thickest in fundus, thinnest in cervix Thicker middle layer = circular Inner and outer layers = longitudinal or oblique Contractions stimulated by oxytocin Uterus

Histology 3 layers Endometrium highly vascularized inner layer Three components Lumen lining Endometrial stroma Endometrial glands Two layers:

Stratum functionalis lines cavity, sloughs off during menstruation Stratum basalis permanent, gives rise to new stratum functionalis after each menstruation Figure 28.18 Histology of the uterus Uterine Blood Supply Supply blood to uterus Internal iliac arteries Uterine arteries Arcuate

arteries Supply stratum basalis Help regenerate stratum functionalis Supply stratum functionalis Change markedly during menstruation Radial arterie s Straight arterioles Spiral arterioles Uterine Veins Internal iliac veins

Myometrium Figure 28.19 Blood supply of the uterus Uterus Cervical mucus produced by cervix mucosa Water, glycoproteins, lipids, enzymes, and inorganic salts Thick or thin Thick = cervical plug, impedes sperm penetration

Thin = ovulation - more hospitable to sperm, more alkaline Supplements energy needs of sperm Cervix + mucus Sperm reservoir Protect sperm from phagocytes Protect sperm from hostile environment of tract Capacitation Wednesday

Notes on the vagina, vulva, perineum, mammary glands. Begin the female reproductive cycle. Clarification from Jason on follicular anatomy: Friday lab period (maybe start lecture.)

theca follicula (theca interna / externa) zona pellucida stromal cells corona radiata basement membrane antrum follicular cells to granulosa cells Reminder female and male repro labs + RYK are due at the end of class Friday Monday start our last topic Vagina 4 tubular fibromuscular canal Lined with mucus membrane

Extends from exterior of body to uterine cervix Functions: Receives penis Passageway for spermatozoa Outlet for menstrual flow Lower portion of birth canal Vagina Mucosa

Muscularis Adventitia Hymen Vagina Mucosa Continuous with uterine mucosa

Decomposition of glycogen makes acidic environment hostile to microbes and sperm Alkaline components of semen raise pH Dendritic cells Areolar CT RUGAE Vagina Muscularis

Adventitia Smooth muscle Outer circular layer & inner longitudinal layer Stretchy Superficial layer areolar CT Anchors vagina to adjacent organs Hymen Thin fold of vascularized mucous membrane

Vulva External Female Genitalia Mons pubis Labia majora Labia minora Homologous to spongy (penile) urethra Clitoris

Homologous to scrotum Homologous to glans penis Vestibule External urethral orifice Vaginal orifice Homologous to intermediate urethra Figure 28.20 Components of the vulva (pudendum) Vulva External Female Genitalia

Hymen Paraurethral (Skenes) gland Homologous to prostate Greater vestibular (Bartholins) gland Homologous to bulbourethral glands Lesser vestibular gland Bulb of the vestibule

Homologous to corpus spongiosum and bulb of penis Perineum Diamond-shaped area medial to thighs and buttocks of males and females Contains external genitalia and anus Figure 28.21 Perineum of a Female Breasts

Breasts hemispheric projections Nipple pigmented projections Openings of lactiferous ducts Areola pigmented area Anterior to pectoralis major &

serratus anterior Fascia Rough = Modified sebaceous glands Suspensory ligaments Mammary glands Mammary gland modified sudoriferous gland that produces milk 15-20 lobes separated by adipose tissue Lobes divided into lobules Lobules composed of alveoli

(milk-secreting glands) Myoepithelial cells Synthesis, secretion & ejection of milk = lactation Prolactin (ant. pit.) & oxytocin (post. pit.) Figure 28.22 Mammary Glands Within the Breast FEMALE REPRODUCTIVE CYCLE

The Female Reproductive Cycle Typical duration 24-35 days; assume 28 days Two components: Ovarian cycle series of events in ovaries that occur during and after maturation of oocyte Uterine (menstrual) cycle concurrent series

of changes in uterine endometrium preparing it for arrival of fertilized ovum Hormonally regulated Hypothalamus, anterior pituitary, ovaries Female Reproductive Cycle Hormones GnRH Hypothalamus FSH

Stimulates anterior pituitary release of LH and FSH Initiates follicular growth Stimulates ovarian follicles to secrete estrogens LH Stimulates ovarian follicle development and estrogen secretion Triggers ovulation Promotes formation of corpus luteum (hence luteinizing) Stimulates

production/secretion of estrogens, progesterone, inhibin, relaxin Female Reproductive Cycle Hormones Estrogens secreted by ovarian follicles Promotes development/maintenance of

female reproductive structures and secondary sex characteristics Stimulates protein anabolism Lowers blood cholesterol At times, inhibits GnRH, LH, FSH Progesterone - secreted mainly by corpus luteum Prepares uterus for implantation Female Reproductive Cycle Hormones Relaxin - produced by corpus luteum

Inhibits uterine contraction Increases flexibility of pubic symphysis Dilates uterine cervix Inhibin produced by follicles and corpus luteum Inhibits secretion of FSH and LH Figure 28.23 Secretion and physiological effects of hormones in the female reproductive cycle Female Reproductive Cycle Phases 1.

Menstrual phase Day 1-5 2. Preovulatory phase Day 6-13 3. Ovulation Day 14 4. Postovulatory phase Day 15-28 Menstrual Phase Day 1-5; first day of menstruation is day 1 Ovarian Events

FSH stimulates primordial follicles to develop into primary follicles Primary follicles develop into secondary follicles Uterine Events Declining estrogen/ progesterone levels stimulate ischemia

in stratum functionalis Stratum functionalis dies and is shed as menstrual discharge Preovulatory Phase Day 6-13 Ovarian Events Secondary follicles secrete estrogen and inhibin One secondary follicle becomes dominant and

develops into a mature follicle Uterine Events Rising estrogen levels stimulate growth of stratum functionalis Referred to as proliferative phase Ovulation Day 14 Ovarian Events

High estrogen levels stimulate GnRH and LH surge LH surge stimulates rupture of mature follicle and release of secondary oocyte into abdominal cavity Uterine Events Stratum functionalis

continues to grow Still referred to as the proliferative phase Figure 28.24 The female reproductive cycle Figure 28.25 Hormonal Control of Ovulation GnRH 1High levels of estrogens from almost mature follicle stimulate release of more GnRH and LH

LH Hypothalamus 2GnRH promotes release of FSH and more LH Anterior pituitary 3LH surge brings about ovulation Ovary Ovulated secondary oocyte Almost mature Corpus hemorrhagicum

(graafian) follicle (ruptured follicle) Surrounded by zona pellucida and corona radiata Postovulatory Phase Day 15-28 Ovarian Events LH stimulates ruptured mature follicle to become corpus luteum Corpus luteum

secretes progesterone, estrogen, relaxin Uterine Events Rising progesterone/estro gen levels promote growth of stratum functionalis (SF) Endometrial glands in SF What Happens if the Oocyte is NOT Fertilized?

In ovary Corpus luteum lifespan = 2 weeks Corpus luteum degenerates into corpus albicans Progesterone and estrogen levels drop GnRH levels rise GnRH stimulates FSH/LH release; follicular growth resumes

A new cycle begins In uterus Decreased progesterone/estrogen levels stimulate ischemia of stratum functionalis; menstruation begins What Happens if the Oocyte is Fertilized? In ovary

Embryo secretes human chorionic gonadotropin (hCG) hCG stimulates corpus luteum to continue secreting progesterone and estrogen Corpus luteums lifespan lasts until placenta takes over hCG in urine = pregnancy test In uterus Continued secretion of progesterone and estrogen maintain thick stratum functionalis, stimulate endometrial glands to secrete glycogen and inhibit menstruation

Preparatory changes peak ~ 1 week after ovulation Figure 28.26 Summary of Hormonal interactions in the ovarian and uterine cycles

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