REPRODUCTIVE SYSTEM

REPRODUCTIVE SYSTEM: Basics Not for Homeostasis; Instead to Perpetuate the Species Sexual Reproduction Results in Genetic Variability Internal Fertilization & Gestation One Offspring per Pregnancy is Typical

REPRODUCTIVE SYSTEM: Functions Production & Support of Gametes Males - Formation, Transport & Delivery of Sperm Females -Formation & Transport of Ova -Protect & Support Developing Embryo, and Nourish Fetus -Deliver the Fetus

REPRODUCTIVE SYSTEM: Overview of Anatomy Reproductive Organs Associated Ducts Accessory Glands External Genitalia

MALE ANATOMY: TESTES From the Greek for “witness” (e.g., testify) Essential organs of reproduction in the male (Male Gonad) Site of sperm production Suspended in scrotum by spermatic cord

MALE ANATOMY: SCROTUM Pouch of skin, fascia, muscle evaginated from anterior abdominal wall Subdivided into two lateral compartments by septum Houses testes, keeps them cool (93  F) Cremaster muscle brings testes closer to body Dartos muscle causes wrinkling

MALE ANATOMY: TESTES Develop initially in abdominal cavity (retroperitoneally) Descend into scrotum -Starts 7th month of gestation -Pass through inguinal canal -Should be in scrotum by birth Continued...

MALE ANATOMY: TESTES CONTINUED Seminiferous tubules: Sites of sperm production Interstitial Cells: Secrete Testosterone Efferent ductules: Carry sperm from testes to: Epididymis: -Store sperm -Site of sperm maturation (2 weeks) Continued...

MALE ANATOMY: SPERMATIC CORD Contains structures passing to and from testes Coverings derived from abdominal wall Contents include: -Vas deferens -Spermatic artery and vein -Spermatic nerve -Lymph vessel -Cremaster muscle

MALE ANATOMY: VAS (DUCTUS) DEFERENS Carries sperm from epididymis toward seminal vesicle Passes through inguinal canal into body cavity Crosses surface of urinary bladder Joins with duct of seminal vesicle to form the ejaculatory duct Vasectomy

MALE ACCESSORY GLANDS: SEMINAL VESICLES Paired structures posterior to urinary bladder Secretes >60% of seminal fluid Fluid is sugary, alkaline Rich in charbohydrates, Vitamin C -Nourishes & protects sperm -Enhances motility & retention in female reproductive tract

MALE ACCESSORY GLANDS : PROSTATE GLAND Located inferior to urinary bladder, anterior to rectum Surrounds prostatic urethra Secretes >25% of seminal fluid Enzymes to liquify semen Secretions that activate sperm

MALE ACCESSORY GLANDS : BULBOURETHRAL GLANDS Also called Cowper’s glands Lateral to membranous urethra Secrete a drop of alkaline mucus prior to ejaculation -Cleans, lubricates urethra -Neutralizes acidic urine -Does not contribute towards semen

MALE ANATOMY: PENIS Male copulatory organ Functions to introduce sperm into female Consists of three erectile bodies -Two corpora cavernosa -One corpus spongiosum

MALE ANATOMY: PENIS Corpus spongiosum -Surrounds penile (spongy) urethra -Forms 1/3 of shaft -Distal end forms glans penis; Urethral orifice opens through glans -Proximal end forms bulb of penis

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MALE ANATOMY: PENIS CONTINUED Corpora cavernosa -Paired, dorsal -Form 2/3 of shaft Prepuce (foreskin): -Covers glans penis -Optionally removed by circumcision

MALE PHYSIOLOGY: SPERMATOGENESIS -Occurs in seminiferous tubules -Spermatogonia divide mitotically -One Spermatocyte eventually gives rise to Four Sperm via meiosis -Fertilization by Y sperm result in male embryo -Fertilization by X sperm results in female embryo

MALE SEXUAL RESPONSE Erection -Arteries dilate, increasing blood in spongy tissue -Constricts veins, causes erection Ejaculation (expulsion) -Semen passes through urethra -Contractions of urethra, penile musculature, ducts

MALE HORMONAL CONTROLS Gonadotropic Hormones -Follicle Stimulating Hormone (stimulates sperm production) -Luteinizing Hormone or ICSH (stimulates testes to secrete testosterone) Testosterone (Male Sex Hormone) -Male Secondary Sex Characteristics

FEMALE ANATOMY: OVARY Female Gonad Follicles – sites of ova production Ova development pauses at birth, resumes following puberty -Approximately 400,000+ follicles -Only about 400 ever reach maturity Paired, oval, almond sized Supported by ligaments

FEMALE ANATOMY: UTERINE (Fallopian) TUBES Site of Fertilization Paired, ~10 cm long Transport via Cilia & Peristalsis Attached to uterus, one on each side -Interstitial segment: Within uterus -Isthmus: Narrow portion adjacent to uterus -Ampulla: Long, wide portion -Infundibulum: Funnel-shaped end with branches, fimbriae, that drape over ovary

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FEMALE ANATOMY: UTERUS Unpaired, hollow, muscular, pear- shaped organ Receives uterine tubes, empties into vagina Site of Implantation & Development Supported by ligaments: -Broad ligament: Double layer of peritoneum -Round ligaments: Pass through inguinal canal

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FEMALE ANATOMY: UTERUS Fundus: Raised region above entry of uterine tubes Body: Central region w/large triangular lumen Isthmus: Narrowed region between body & cervix Cervix: -Most inferior portion -Extends down into vagina

FEMALE ANATOMY: UTERUS continued Uterine wall has three layers -Perimetrium (broad ligament) or Visceral Peritoneum -Myometrium: Thick layer of smooth muscle -Endometrium: * Epithelial layer * Undergoes cyclic changes in response to hormones *Subject to Endometriosis

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FEMALE ANATOMY: VAGINA Functions: -Receives penis during intercourse -Passage for removal of menstrual debris -Serves as a birth canal Located between urethra and rectum Lined with stratified squamous E.T. Acidic environment (resident bacteria)

FEMALE ANATOMY: VAGINA continued Fornix: Circular recess around cervix; upper portion of vagina Hymen: *Fold of mucous membrane *Does NOT signify virginity! Greater Vestibular Glands (Bartholin’s): -Distal end vagina -Homologous to Cowper’s glands -Very little secretion (mucus)

Vulva

FEMALE ANATOMY: VULVA (External Genitalia) Mons pubis: Fatty mound Labia majora: Outer folds of skin; Homologous to scrotum Labia minora: Inner folds, encircle clitoris, forms prepuce (foreskin) Clitoris: Homologous to penis; composed of corpora cavernosa

FEMALE ANATOMY: CLITORIS Partially covered by prepuce (foreskin) Function – Sexual pleasure Orgasm controlled by Sympathetic Division of ANS

FEMALE ANATOMY: BREASTS Structurally – Integument Functionally – Reproductive -Colostrum -Breast Milk

HORMONAL CONTROL: ADULT FEMALE Four hormones involved: -FSH and LH (from pituitary) *Targets ovaries *Follicles w/ova grow & mature *Ovaries secrete: -Estrogen and progesterone (from ovaries) *Target uterus *Endometrium thickens & secretes

THE OVARIAN CYCLE Includes: -Follicular Phase *Follicle development/maturation & Oogenesis -Ovulation -Luteal Phase *Development of corpus luteum from ruptured follicle

FOLLICLE DEVELOPMENT Up to 20 follicles begin maturation process cyclically Only one secondary follicle reaches maturity Others undergo atresia (degradation) Controlled primarily by FSH FSH causes follicle cells to secrete estrogen

OVULATION Caused by LH surge Day 14 (28-day cycle) Expels ovum into abdominal cavity Fimbriae on uterine tube sway vigorously, producing a current Fimbriae scratch Graafian follicle, rupture it, sweep ovum into tube

FORMATION OF CORPUS LUTEUM Ruptured mature (Graafian) follicle becomes corpus luteum Corpus luteum secretes estrogen, progesterone Maintains endometrial lining during pregnancy

Stages of Follicular Development

THE UTERINE CYCLE Menstrual phase (Day 1 of 28-day cycle) Proliferative phase -Follows Menstruation -Estrogen from follicle stimulates proliferation of endometrium Secretory phase -Follows Ovulation -Progesterone from corpus luteum stimulates secretion by endometrium

Ovarian Hormones Control the Endometrial Changes of the Uterine Cycle Ovarian Cycle Follicular phase  (Estrogens) Luteal phase  (Progesterone) Uterine Cycle Proliferative phase Secretory phase