Bio 182- Ecology Unit Outline 1

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1 Bio 182- Ecology Unit Outline 1 Reproductive System Introduction 1. Functions: a. Procreation b. Bonding between sexes 2. Gonads: a. Male-testes b. Female-ovaries Male Reproductive System Male Reproductive System 1. Scrotum a. Cutaneous outpocketing of abdominal cavity b. Houses male gonad: testes c. Dartos muscle: smooth muscle that causes skin wrinkling of scrotum d. Cremaster muscle: skeletal muscle that elevates testes during cold or sexual arousal 1) Sperm develops best at 3 C below body temperature (38 C) 2) Reflex 2. Testes a. Paired oval glands about 5 X 2.5 cm in dimensions b. Mass: grams c. Descend into scrotal sac from abdominal cavity through inguinal canal during end of 7 th month 1) Cryptochidism-failure of testes to descend; if uncorrected results in sterility d. Divided into lobules-internal compartments that house roughly 1-3 tightly coiled seminiferous tubules 1) Site of spermatogenesis-process of sperm formation by mitosis and meiosis 2) From outer edge towards luminal surface: a) Spermatogonia (2n)-cells touch basement membrane; divide by mitosis to form primary spermatocytes b) Primary (1 o ) spermatocytes (2n)-second layer in; these cells divide by meiosis I forming secondary spermatocytes c) Secondary (2 o ) spermatocytes (n)-3 rd layer in; complete meiosis II and form spermatids (n) d) Spermatids (n)-luminal edge; these eventually mature into spermatozoa 3) Sertoli or sustentacular cells a) Nourish spermatozoans b) Form blood-testis barrier c) Phagocytize excess cytoplasm from developing spermatids

2 Bio 182- Ecology Unit Outline 2 d) Control sperm movements e) Secrete hormone inhibin-regulates sperm production by inhibiting FSH 4) Interstitial cells of Leydig a) Found between tubules b) Secrete testosterone c) ICSH (from adenohypophysis) controls release of testosterone from interstitial cells of Leydig 5) Blood-testis barrier is formed by tight junctions between sustentacular cells a) Sperm cells contain unique surface antigens-activate immune system if barrier not present e. Seminiferous tubules unite to form straight tubules f. Straight tubules bend into a series of anastomosing ducts called rete testis g. The rete testis lead into a network of tubules on outer surface of testis called the epididymis h. Epididymis (plural: epididymides) 1) 6 m long; 18 ft when uncoiled 2) Lies along posterior border of testis 3) Functions: a) Site of sperm maturation b) Reabsorbs degenerating spermatozoans c) Sperm storage-up to days i. Ductus deferens 1) Epididymis transitions into the ductus (vas) deferens a) ~ 18 in long X 2 mm diameter 2) Enters inguinal canal and once in abdominal cavity loops over side & down posterior surface of urinary bladder where it joins the urethra 3) Functions: a) Stores sperm for days b) Conveys sperm to urethra for ejaculation; lined with thick smooth muscle that cause powerful peristaltic waves 4) Vasectomy-portion of each ductus deferens is removed; ends cauterized and returned to scrotum 3. Urethra a. Divided into 3 regions: prostatic, membranous, & penile b. Totals 20 cm long 4. Penis a. Intromitive organ b. Root-at base; muscle activity here causes erection c. Body-3 cylindrical masses of tissue filled with blood sinuses 1) Arteries dilate with sexual stimulation allowing blood entry; expansion compresses veins draining penis sustaining erection

3 Bio 182- Ecology Unit Outline 3 d. Glans penis-slightly enlarged acorn-shaped region 1) External urethral orifice-urine and sperm exit 2) Prepuce or foreskin covers 5. Spermatogenesis a. see earlier slides b. Reduction from diploid # (2n = 46) to haploid # (n = 23) c. Takes 74 days d. Spermatids reside on luminal surface of seminiferous tubules 1) Still united by cytoplasmic bridges 2) Half are X bearing and half are Y bearing 3) Larger X chromosome may carry info to complete spermatogenesis 4) Cytoplasm drained off by Sertoli cells e. Maturation of spermatids into spermatozoans is spermiogenesis 6. Spermiogenesis-changes transform spermatids into spermatozoa a. Discard excess cytoplasm and growing flagellum b. Spermatozoans 1) Spend days in epididymis maturing 2) 300 million/day formed 3) 48 hr life expectancy once ejaculated 4) Regions: a) Head-houses nucleus (paternal set) and acrosome-ezcontaining granule with specialized lysosomes b) Midpiece-houses mitochondria c) Flagellum-whip-like structure for propulsion 7. Accessory glands a. Secrete liquid portion of semen b. Sperm + accessory gland secretions called semen c. Seminal vesicles 1) ~ 5 cm long 2) Paired, convoluted, pouch-like structures at the base of urinary bladder in front of rectum 3) Secrete a slightly alkaline viscous yellowish fluid of: a) Fructose-for sperm ATP synthesis b) PG s-for sperm motility & viability; also stimulates muscular contractions of female tract c) Fibrinogen-coagulates semen forming a temporary clot after ejaculation 4) 60% of volume d. Prostate gland 1) Single- doughnt-shaped gland; 4 cm diameter 2) Inferior to bladder & surrounds superior portion of urethra 3) Secretes a milky, slightly acidic fluid of: a) Citric acid b) Clotting EZ s

4 Bio 182- Ecology Unit Outline 4 c) Acid phophatase d) Fibrinolysin e) Seminalplasmin-antibiotic that may prevent urinary tract infections 4) 25% of volume e. Bulbourethral glands 1) Paired, pea-sized (1 cm) glands on each side of urethra at base of penis 2) Thick, alkaline fluid that protects sperm from acidic vagina 3) Also, lubricates urethra to decrease number of injured sperm (during ejaculation) and help with intercourse f. Semen (ph ) 1) ml per ejaculation 2) million sperm/ml-combined action of sperm secreting hyaluronidase & proteinases digest ovum covering 8. Parasympathetic signals & sexual response a. PS signals produce an erection with direct stimulation of penis and other perineal organs Female Reproductive System Female Reproductive System 1. Ovaries a. Paired oval glands resembling unshelled almonds b. Homologous to testes c. Reside in upper pelvic cavity d. Anchored by broad ligament of uterus and mesovarium e. Histology: 1) Germinal epithelium-simple squamous epithelium covering surface; name is misleading because it does not give rise to ova 2) Tunica albuginea-dense irregular CT deep to germinal layer 3) Stroma-CT deep to albuginea; cortex contains follicles & medulla is inner region 2. Oogenesis and sexual cycle a. Reproductive cycle is events occurring between fertilization and birth b. Sexual cycle is the events recurring every month when pregnancy does not occur 1) Ovarian cycle-events in ovaries 2) Mentrual cycle-parallel changes in uterus c. Stages of ovarian cycle 1) Primordial follicle-single layer of squamous cells surrounding primary oocyte 2) Primary follicle-single layer of cuboidal cells surrounding primary oocyte 3) Secondary follicle-multiple layers of cuboidal cells; fluid secreted into a space

5 Bio 182- Ecology Unit Outline 5 4) Graafian (= mature) follicle-large, fluid-filled structure housing secondary oocyte 5) Corpus hemorrhagicum-ruptured follcile w/o secondary oocyte; formed immediately after ovulation when follicle fills with blood 6) Corpus luteum-ruptured yellowish, follicle w/o secondary oocyte that secretes hormones that maintain early pregnancy 7) Corpus albicans-corpus luteum replaced by fibrous CT and is white in appearance from scar tissue 3. Fallopian tubes a. Also called oviducts or uterine tubes b. Found on superiolateral surface of ovary; ~ 10 cm long c. Distal end is called infundibulum; has fingerlike projections called fimbriae 1) Infundibulum captures egg 2) Fimbriae create movements that pull egg into tube 3) Rest of tube conducts egg to uterus d. Histology 1) Mucosa a) Ciliated simple columnar epithelium-helps sweep egg along tube b) Secretory cells with many microvilli nourish developing embryo 2) Muscularis-smooth muscle creates peristaltic waves 3) Serosa 4. Uterus a. Also called the womb b. Functions: 1) Path for sperm travel to egg 2) Site for implantation and fetal development 3) Expels fetus by contractions during parturition c. Regions 1) Fundus-dome-shaped superior area 2) Body-tapering central region 3) Cervix-inferior narrow area separating uterus from vagina a) Secretes cervical mucus-alkaline mixture of water, proteins, lipids, salts, & EZ s (some of the nourish spermatozoans) b) At ovulation mucus is less vicous & at other times is thick enough to plug uterus entry d. Histology 1) Perimetrium-outer layer of visceral peritoneum 2) Myometrium-middle layer of smooth muscle that forms bulk of wall a) Cells here respond strongly to OT at birth 3) Endometrium-inner, highly vascular layer a) Luminal surface is simple ciliated columnar epithelium

6 Bio 182- Ecology Unit Outline 6 b) Endometrial or uterine glands present-secretion function c) Stroma-very thick lamina propria divided into stratum basalis and stratus functionalis i. S. functionalis-lines lumen & is shed during menstruation ii. S. basalis-permanent layer that regenerates loss cells d) Spiral arterioles-penetrate functionalis layer; constriction results in death of tissue and loss during menstruation e. Tests and Procedures 1) Pap (Papanicolaou) smear-cells removed from cervix and upper vagina and examined for cancer 2) D (Dilation) & C (Curettage)-cervix is dialted & uterus is scraped with a spoon-shaped instrument called a curette; removes potentially cancerous uterine lining 3) Hysterectomy-removal of uterus a) Causes: endometriosus, fibroids, prolapse 5. Vagina a. Also called birth canal b. Tubular, muscular organ ~ 10 cm long c. Functions: 1) Receptive site for penis & sperm 2) Menstrual flow exit 3) Birth canal d. Histology: 1) Mucosa-stratified squamous epithelium; folds into rugae a) Dendritic cells are antigen-presenting cells that can be involved in HIV transmission b) Orifice may be covered by fold of vascularized membrane called the hymen 2) Muscularis-smooth muscle 3) Serosa 6. The Vulva (Pedendum) a. Defined: external genitalia of female b. Mons pubis-mound of fat over pubic symphysis c. Labia majora-thick folds of skin surrounded by pubic hair d. Labia minora-more medial, thin hairless folds 1) Form vestibule, space between labia, containing urethral & vaginal openings 2) Form hoodlike prepuce over clitoris e. Clitoris-erotic, sensory organ (homologous to male penis) f. Vestibular bulbs-erectile tissue around vagina g. Paraurethral and vestibular glands (greater & lesser) open into vestibule for lubrication 7. Oogenesis

7 Bio 182- Ecology Unit Outline 7 a. Process that forms haploid ovum (plural ova) b. In fetus, primordial germ cells migrate from endoderm to ovaries and then differentiate into oogonia-2n precursors to ova c. About 3 rd month of development, oogonia divide by mitosis to form primary oocytes d. Primary (1 o ) oocytes divide by meiosis I and enter prophase I before puberty 1) Each primary oocyte is surrounded by a single layer of squamous epithelial cells forming a primordial foliicle 2) 200,000-2,000,000 primordial follicles originally present, but by puberty most have undergone atresia (~ 40,000 left) e. At puberty, FSH secretion rises and primordial follicles respond, but only a few make it to the next stage, the primary follicle f. Primary follicle contain primary oocyte surrounded by several layers of cuboidally-shaped cells 1) Primary oocyte completes meiosis I 2) Uneven cytokinesis forms first polar body 3) Larger cell is called a secondary oocyte g. Secondary (2 o ) oocyte goes to metaphase II and stops 1) Does not complete meiosis until after ovulation & fertilization 2) Technically, ovulation involves a secondary oocyte (not an egg) h. Cells of primary follicle begin secreting fluids into cavity called the antrum i. Primary follicle enlarges into a secondary follicle with visible fluid-filled space j. Eventually, under FSH & estrogen, influences, secondary follicle enlarges into a Graafian, or mature, follicle 1) Graafian follicle forms blister-like bulge on ovary wall 2) LH induces rupture and release (ovulation) of 2 o oocyte into nearby Fallopian tube k. If fertilization takes place, 2 o oocyte completes meiosis II producing the ovum & a 2 nd polar body 1) Polar bodies degenerate 8. Sexual or Reproductive Cycle a. Averages 28 days, but ranges from days b. Hormone cycle produces hierarchy of control 1) hypothalamus-à pituitary-à ovaries-à uterus c. General phases: 1) Follicular phase (2 weeks) a) Menstruation (menstrual phase) occurs during first 3 to 5 days b) Uterus replaces lost endometrium & follicles grow (preovulatory phase 2) Postovulatory phase (2 weeks)

8 Bio 182- Ecology Unit Outline 8 1) Corpus luteum stimulates endometrial thickening 2) Endometrium lost again if pregnancy does not occur d. Specific phases of ovarian cycle: 1) Follicular phase-from beginning of menstruation (1) to ovulation (14) a) Most variable part of cycle b) Seldom possible to predict date of ovulation c) Contains menstrual and preovulatory phases d) Menstrual phase-discharge of menstrual fluid (Days 1-5) i. ~ 25 primary oocytes that began developing on day 25 of previous cycle have been transformed into secondary follicles by day 5--follicular fluid and corona radiata have formed e) Preovulatory phase-from end of menstruation to ovulation (days 6-13) i. At day 6, one follicle begins to grow faster than others ii. Increased estrogen levels inhibit FSH causing other follicles to stop growing iii. Estrogen from this follicle sustains own growth and also promotes repair of endometrium iv. Now a Graafian follicle, it forms a large bulge on outer ovary wall v. With decrease of FSH, LH increases vi. secondary oocyte has now reached metaphase II 2) Ovulation a) Day 14-rupture of Graafian follicle and release of secondary oocyte into fallopian tube b) High estrogen levels have caused adenohypophysis to secrete LH-increased blood flow causes follicle to swell rapidly collagenase weakens ovarian wall fluid oozes out with secondary oocyte swept up into uterine tube by fimbriae c) Positive feedback loop quickly broken by increasing progesterone levels in postovulatory phase 3) Postovulatory phase-from end of ovulation to beginning of menstruation (days 15-28) a) Ruptured Graafian follicle becomes corpus hemorrhagicum; this crater-like pocket fills with blood b) LH stimulates formation of corpus luteum c) Progesterone & estrogen are secreted by corpus luteum preparing uterus for implantation d) Endometrium changes: i. Glands begin to coil & grow ii. Synthesis of glycogen iii. Increased blood vessel growth

9 Bio 182- Ecology Unit Outline 9 4) If fertilization does NOT occur: a) Rising levels of progesterone & estrogen inhibit GnRH & LH b) Corpus luteum degenerates and becomes corpus albicans c) Later in postovulatory phase, decrease of progesterone & estrogen initiate next cycle d) At day 25 of postovulatory phase, FSH has started to increase again causing development of next group of follicles 5) If fertilization DOES occur: a) Corpus luteum is maintained & produces hormones until placenta takes over b) Corpus luteum is maintained by the H Human Chorionic Gonadotropin (hcg) i. hcg comes from chorionic membrane ii. Chorionic membrane develops into placenta iii. hcg is a pregnancy indicator c) Placenta secretes estrogen & progesterone to support pregnancy & promote breast development d) Role of corpus luteum is minor after placenta forms e. Menstrual Cycle-changes in uterus 1) Menstrual Phase a) Blood, serous fluid, and endometrial tissue discharged b) Average female loses 40 ml of blood & 35 ml of serous fluidcontains fibrinolysin so it does not clot 2) Proliferative phase a) Time of rebuilding endometrial tissue lost at menstruation; mitosis in stratum basalis b) Result of estrogen from developing follicles c) Uterus lining reaches 2-3 mm thickness 3) Secretory phase a) Further thickening of endometrium due to secretion & fluid accumulation-not mitosis b) Due to progesterone stimulation of glands c) Uterus reaches 5-6 mm thickness 4) Premenstrual phase a) Progesterone level fall due to atrophy of corpus luteum b) Spiral arterioles constrict causing endometrial ischemia c) Pools of blood accumulate in stratum functionalis 9. Hormones of Pregnancy a. hcg (Human chorionic gonadotropin) 1) Secreted by trophoblast within 9 days of conception 2) Stimulates growth of corpus luteum b. Estrogens 1) Increases to 30X normal before birth 2) Corpus luteum is source for first 12 weeks then placenta takes over

10 Bio 182- Ecology Unit Outline 10 3) Causes uterine, mammary duct, & breast enlargement c. Progesterone secreted by placenta & corpus luteum 1) Suppresses secretion of FSH & LH preventing follicular development 2) Prevents menstruation and thickens endometrium 3) Stimulates development of acini in breast tissue 10. Sex differentiation a. Male & female are indistinguishable for first 8-10 weeks of development b. Female develops due to absence of H s 1) Absence of testosterone (& others) causes degeneration of embryonic ducts 2) Phallus becomes clitoris in females and testosterone increases size causing phallus to become penis in males 3) Urogenital folds develop into labia minora & labioscrotal folds into labia majora; in males labia majora close and become scrotal sac

Chapter 26: Reproductive Systems. Male 11/29/2015. Male reproductive system is composed of... BIO 218 Fall Gonads (testes)

Chapter 26: Reproductive Systems BIO 218 Fall 2015 Male Male reproductive system is composed of... Gonads (testes) Duct system (epididymis, ductus deferens, ejaculatory ducts, urethra) Accessory sex glands