REPRODUCTIVE SYSTEM

The Reproductive Systems : 

28-1 The Reproductive Systems Sexual reproduction produces new individuals germ cells called gametes (sperm & 2nd oocyte) fertilization produces one cell with one set of chromosomes from each parent Gonads produce gametes & secrete sex hormones Reproductive systems gonads, ducts, glands & supporting structures (uterus and penis) Gynecology is study of female reproductive system (dignosis and treatment) Urology is study of urinary system & male reproductive system

Male Reproductive System : 

28-2 Male Reproductive System Gonads, ducts, sex glands & supporting structures Semen contains sperm plus glandular secretions

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28-3 Testis Vas-deferens Seminal vesicles Prostate Bulbourethral and Cowper’s glands Penis

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28-4 Testis - Two oval shaped bodies in scrotal bags - Scrotal helps to maintain temperature little lower then body - High temp. reduces the production of spermatozoa In T. S. testis is partitioned into various lobuled Lobule is filled with convoluted seminiferous tubules Each tubule is 50 cm in length Some interstitial cells secrets testosterone which provide glycogen and nutrition to spermatozoa.

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28-6 Functions of Testes: Two functions To produce spermatozoa To secrete testosterone Spermatozoa(Sperm): Produced by seminiferous tubules by spermatogenesis Spermatogenesis is formation of sperm cells from spermatogonia.

Supporting Cells of Sperm Formation : 

28-7 Supporting Cells of Sperm Formation Sertoli cells -- extend from basement membrane to lumen form blood-testis barrier support developing sperm cells produce fluid & control release of sperm into lumen

Spermatogenesis : 

28-8 Spermatogenesis Spermatogonium (stem cells) give rise to 2 daughter cells by mitosis One daughter cell kept in reserve -- other becomes primary spermatocyte Primary spermatocyte goes through meiosis I

Spermatogenesis : 

28-9 Spermatogenesis Secondary spermatocytes are formed 23 chromosomes of which each is 2 chromatids joined by centromere goes through meiosis II 4 spermatids are formed each is haploid & unique all 4 remain in contact with cytoplasmic bridge accounts for synchronized release of sperm that are 50% X chromosome & 50% Y chromosome

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28-10 Sperm has Head (has nucleus), neck, body(has rings of fibrils with a sheath) and Tail (has fibril with sheath but end part is only fibril.) Sperm can be alive for 1 – 2 months In female genital tract - live for 2-3 days

Semen : 

28-11 Semen Mixture of sperm & seminal fluid glandular secretions and fluid of seminiferous tubules slightly alkaline, milky appearance, sticky contains nutrients, clotting proteins & antibiotic seminalplasmin Typical ejaculate is 2.5 to 5 ml in volume Normal sperm count is 50 to 150 million/ml actions of many are needed for one to enter Coagulates within 5 minutes -- reliquefies in 15 due to enzymes produced by the prostate gland Semen analysis----bad news if show lack of forward motility, low count (20 millions /cc) or abnormal shapes

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28-12 2. Vas-deferens: Seminiferous tubules unite to form Rete- testes from where vasa- efferentia/ efferent ductule starts. Vasa efferent form epididymis (head, body and tail) Epididymis contineue to form Vas-deferens Vas diferens enters into the proststic part of the urethra It join to ejaculatory duct Which receives secretions from the Prostate gland Seminal vesicles and Cowper’s gland/ bulbourethral gland This secretion form major part of semen.

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28-13 Seminiferous tubules Rete- testes vasa- efferentia/ efferent ductule epididymis (head, body and tail) Vas-deferens ejaculatory duct Which receives secretions from the Prostate gland Seminal vesicles and Cowper’s gland/ bulbourethral gland

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28-14 Seminiferous tubules Rete- testes vasa- efferentia/ efferent ductule epididymis (head, body and tail) Vas-deferens ejaculatory duct Which receives secretions from the Prostate gland Seminal vesicles and Cowper’s gland/ bulbourethral gland

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28-15 3. Seminal Vesicles Secretes most of semen secretion Fructose+ prostaglandins+ clotting proteins (eg semenogelin) This secretion+ prostate secretion+ Spermatozoa (sperm) form secretion.

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28-16 4. Prostate Dough nut shaped gland prostate gland is about 1.2 inches high by 1.6 inches wide by 0.8 inch deep (3 cm by 4 cm by 2 cm) A muscular gland just below the urinary bladder, It surrounds the first inch of the urethra The glandular tissue of the prostate secretes an alkaline fluid that helps maintain sperm motility. The smooth muscle of the prostate gland contracts during ejaculation to contribute to the expulsion of semen from the urethra.

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28-17 5. Bulbourethral OR Cowper’s glands Located below the prostate gland; they empty into the urethra. Their alkaline secretion coats the interior of the urethra just before ejaculation, which neutralizes any acidic urine. You have probably noticed that the secretions of the male reproductive glands are alkaline. This is important because the cavity of the female vagina has an acidic pH created by the normal flora, the natural bacterial population of the vagina. The alkalinity of seminal fluid helps neutralize the acidic vaginal pH and permits sperm motility in what might otherwise be an unfavorable environment.

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28-18 6. Urethra –Penis the last ducts through which semen travels Its longest portion is enclosed within the penis. The penis is an external genital organ; its distal end is called the glans penis and is covered with a fold of skin called the foreskin. Circumcision is the surgical removal of the foreskin. Within the penis are three masses of erectile tissue (Each consists smooth muscle + connective tissue +blood sinuses) Blood flow is minimal, the penis is flaccid. During sexual stimulation, the arteries to the penis dilate, and the penis becomes erect and firm. The dilation of penile arteries due to NO & by parasympathetic impulses and the resulting erection is capable of penetrating and depositing sperm. Ejaculation is a sympathetic response that is brought about by peristalsis of all of the reproductive ducts and contraction of the prostate gland and the muscles of the pelvic floor.

Cross-Section of Penis : 

28-19 Cross-Section of Penis Corpora cavernosa upper paired, erectile tissue masses Corpus spongiosum lower erectile tissue mass surrounds urethra begins as bulb of penis covered by bulbospongiosus muscle ends as glans penis

Hormonal Effects of Testosterone : 

28-20 Hormonal Effects of Testosterone Testosterone & DHT bind to receptors in cell nucleus & change genetic activity Prenatal effect is born a male At puberty, final development of 2nd sexual characteristics and adult reproductive system sexual behavior & libido male metabolism (bone & muscle mass heavier) deepening of the voice

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Female Reproductive System 28-21

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28-22 Female Reproductive System External Genitals / vulva The mons pubis: is a pad of fat over the pubic symphysis, covered with skin and pubic hair. b) Clitoris: A small mass of erectile tissue anterior to the urethral orifice Function is sensory (responds to sexual stimulation, and its vascular sinuses become filled with blood) c) labia majora and minora: are paired folds of skin The area between the labia minora is called the vestibule and contains the openings of the urethra and vagina d)Bartholin’s glands/ vestibular glands: secretion of these glands keeps the mucosa moist and lubricates the vagina during sexual intercourse.

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28-23 Female Reproductive System I) External Genitals / vulva

Female Reproductive System : 

28-24 Female Reproductive System II) Internal Ovaries produce 2nd oocytes & hormones Uterine tubes transport fertilized ova Uterus where fetal development occurs Vagina & external genitalia constitute the vulva Mammary glands produce milk

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28-25 Corpus luteum Fertilization of ovum Fallopian tube Fundus of uterus Ovarian ligament Fimbriae Mature follicle Broad ligament Round ligament Artery and vein Body of uterus Endometrium Myometrium Sperm Cervix of uterus Vagina Bartholin's gland

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28-26 1. VAGINA A muscular tube about 4 inches (10 cm) long Extends from the cervix to the vaginal orifice It is posterior to the urethra and anterior to the rectum The normal flora (bacteria) of the vagina creates an acidic pH that helps inhibit the growth of pathogens. Functions to receive sperm from the penis during sexual intercourse, to provide the exit for menstrual blood flow, and to become the birth canal at the end of pregnancy.

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28-27 2. UTERUS like an upside-down pear, 3 inches long by 2 inches wide by 1 inch deep (7.5 cm by 5 cm by 2.5 cm), superior to the urinary bladder and between the two ovaries in the pelvic cavity During pregnancy the uterus increases greatly in size, Contains the placenta to nourish the embryo-fetus Expels the baby at the end of gestation. The parts of uterus are as follows- 1.Fundus is the upper portion above the entry of the fallopian tubes 2. Body is the large central portion. 3. The narrow, lower end of the uterus is the cervix, which opens into the vagina.

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28-28 Layer of the uterus: The outermost --- serosa or epimetrium (a fold of the peritoneum) The myometrium ---smooth muscle layer (during pregnancy these cells increase in size contract for labor) Endometrium Two layers The basilar layer, adjacent to the myometrium, is vascular but very thin and is a permanent layer. 2. The functional layer is regenerated and lost during each menstrual cycle. Under the influence of estrogen and progesterone from the ovaries, the growth of blood vessels thickens the functional layer in preparation for a possible embryo. If fertilization does not occur, the functional layer sloughs off in menstruation.

Histology of the Uterus : 

28-29 Histology of the Uterus Endometrium simple columnar epithelium stroma of connective tissue and endometrial glands stratum functionalis shed during menstruation stratum basalis replaces stratum functionalis each month Myometrium 3 layers of smooth muscle Perimetrium visceral peritoneum

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28-30 3. FALLOPIAN TUBES/ Uterine tubes or oviducts Each is about 4 inches (10 cm) long. Lateral end encloses an ovary, Medial end opens into the uterus. Tube has fimbriae, peristaltic waves, ciliated epithelial tissue Fimbriae (fringelike projections) pull the ovum into the fallopian tube. As Ovum has no self-locomotion (like sperm) b) Peristaltic waves propel the ovum c) Sweeping action of the cilia also moves the ovum toward the uterus. Fertilization takes place in the fallopian tube. If not than ovum dies within 24 to 48 hours and disintegrates, either in the tube or the uterus. If fertilized, the ovum becomes a zygote and is swept into the uterus; this takes about 4 to 5 days Ectopic pregnancy; ectopic means “in an abnormal site.” Sometimes the zygote will not reach the uterus but will still continue to develop.

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28-31 4. OVARIES Pair of oval structures about 1.5 inches (4 cm) long in the pelvic cavity Ligaments help to keep the ovaries in place. An ovary has several hundred thousand primary follicles, which are present at birth. During a woman’s childbearing years, only 300 to 400 of these follicles will produce mature ova. Each primary ovarian follicle contains an oocyte /ovum/egg cell. The follicle cells, which secrete estrogen surrounding the oocyte. Maturation of a follicle, requiring FSH and estrogen A mature follicle (graafian follicle), and the hormone LH from the anterior pituitary gland causes ovulation (rupture of the mature follicle with release of the ovum). Other developing follicles (atretic follicles) begin to deteriorate Under the influence of LH, the ruptured follicle becomes the corpus luteum and begins to secrete progesterone , estrogen & in smaller amounts inhibin and relaxin.

Review of Oogenesis : 

28-32 Review of Oogenesis

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28-33 5. MAMMARY GLANDS The mammary glands are structurally related to the skin Functionally related to the reproductive system because they produce milk for the nourishment of offspring. Read functions of Estrogen, Progesteron and testosteron from Derasari

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28-34 III rd Lecture

Female Reproductive Cycle : 

28-35 Female Reproductive Cycle Controlled by monthly hormone cycle of anterior pituitary, hypothalamus & ovary Monthly cycle of changes in ovary and uterus Ovarian cycle changes in ovary during & after maturation of oocyte Uterine cycle preparation of uterus to receive fertilized ovum if implantation does not occur, the stratum functionalis is shed during menstruation

Overview of Hormonal Regulation of Reproductive Cycle : 

28-36 Overview of Hormonal Regulation of Reproductive Cycle

Phases of Female Reproductive Cycle : 

28-37 Phases of Female Reproductive Cycle

Follicular Stages : 

28-38 Follicular Stages Stages of follicular development primordial primary secondary graafian ovulation Corpus luteum is ovulation wound fills in with hormone secreting cells Corpus albicans is white scar left after corpus luteum is not needed

Review of Oogenesis : 

28-39 Review of Oogenesis

I) Menstrual Phase : 

28-40 I) Menstrual Phase Menstruation lasts for 5 days First day is considered beginning of 28 day cycle In ovary 20 follicles that began to develop 6 days before are now beginning to secrete estrogen fluid is filling the antrum from granulosa cells In uterus declining levels of progesterone caused spiral arteries to constrict -- glandular tissue dies stratum functionalis layer is sloughed off along with 50 to 150 ml of blood

Preovulatory Phase : 

28-41 Preovulatory Phase Lasts from day 6 to 13 (most variable timeline) In the ovary (follicular phase) follicular secretion of estrogen & inhibin has slowed the secretion of FSH dominant follicles survives to day 6 by day 14, graafian follicle has enlarged & bulges at surface increasing estrogen levels trigger the secretion of LH In the uterus (proliferative phase) increasing estrogen levels have repaired & thickened the stratum functionalis to 4-10 mm in thickness

Ovulation : 

28-42 Ovulation Rupture of follicle & release of 2nd oocyte on day 14 Cause increasing levels of estrogen stimulate release of GnRH which stimulates anterior pituitary to release more LH Corpus hemorrhagicum results

Postovulatory Phase : 

28-43 Postovulatory Phase Most constant timeline = lasts 14 days In the ovary (luteal phase) if fertilization did not occur, corpus albicans is formed as hormone levels drop, secretion of GnRH, FSH & LH rise if fertilization did occur, developing embryo secretes human chorionic gonadotropin (hCG) which maintains health of corpus luteum & its hormone secretions In the uterus (secretory phase) hormones from corpus luteum promote thickening of endometrium to 12-18 mm formation of more endometrial glands & vascularization if no fertilization occurs, menstrual phase will begin

Negative Feedback on GnRH : 

28-44 Negative Feedback on GnRH

Hormonal Changes : 

28-45 Hormonal Changes

COITUS & FERTILIZATIONErection & Ejaculation : 

28-46 COITUS & FERTILIZATIONErection & Ejaculation Erection sexual stimulation dilates the arteries supplying the penis blood enters the penis compressing the veins so that the blood is trapped. parasympathetic reflex causes erection Ejaculation muscle contractions close sphincter at base of bladder and move fluids through ductus deferens, seminal vesicles, & ejaculatory ducts

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28-47 COITUS & FERTILIZATION Millions of sperm are deposited only one will fertilize an OVUM Sperm uterus and fallopian tube final metabolic change capacitation (involves the acrosome an enzyme) digest the layers of cells and membrane around an ovum. Sperm enters the ovum, membrane block the entry of other sperm. Ovum completes the second meiotic division, and The nuclei of ovum and sperm fuse, forming diploid zygote.

Review of Oogenesis : 

28-48 Review of Oogenesis

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28-49 The human diploid number of 46 chromosomes is actually 23 pairs of chromosomes. 23 from the sperm and 23 from the egg. These 23 pairs consist of 22 pairs of autosomes and one pair of sex chromosomes. Women have the sex chromosomes XX, and men have the sex chromosomes XY. The Y chromosome has a gene that triggers the development of male gonads in the embryo. In the absence of the Y chromosome, the embryo will develop as a female.

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28-50 IMPLANTATION Fertilization in the fallopian tube the zygote divide (mitotic divisions, called cleavage) swept toward the uterus. These are. The single-cell zygote divides into a two-cell stage,four-cell stage, eight-cell stage, and so on. Three days after fertilization there are 16 cells divide form a solid sphere of cells, morula mitosis proceeds this sphere becomes hollow, blastocyst but has same size as the original zygote. A fluid-filled blastocyst consists of an outer layer of cells called the trophoblast and an inner cell mass that contains the potential embryo. It is the blastocyst stage that becomes implanted in the uterine wall, about 5 to 8 days after fertilization.

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28-51 IMPLANTATION The single-cell zygote divides into a two-cell stage,four-cell so on. Three days after fertilization there are 16 cells divide form a solid sphere of cells, morula mitosis proceeds this sphere becomes hollow, blastocyst but has same size as the original zygote. A fluid-filled blastocyst consists of an outer layer of cells called the trophoblast and an inner cell mass that contains the potential embryo. It is the blastocyst stage that becomes implanted in the uterine wall, about 5 to 8 days after fertilization.

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28-52 The endometrium produces carbohydrate “docking” molecules the blastocyst has a surface protein that fits the docking the trophoblast secretes enzymes to digest the surface of endometrium, creating a small crater into which the blastocyst sinks. The trophoblast will become the chorion, the embryonic membrane that will form the fetal portion of the placenta.

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28-53 PLACENTA: The placenta is made of both fetal and maternal tissue. The chorion of the embryo and the endometrium of the uterus contribute, and the placenta is formed (12 weeks). The mature placenta is a flat disc about 7 inches (17 cm) in diameter. The placenta has two functions: tobe the site of exchanges between maternal and fetal blood and to produce hormones to maintain pregnancy. When blood in the umbilical arteries enters the placenta, CO2 and waste products in the fetal capillaries diffuse into the maternal blood sinuses. Oxygen diffuses from the maternal blood sinuses into the fetal capillaries; nutrients enter the fetal blood by diffusion and active transport mechanisms.

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THANK YOU IV th LECTURE 28-54

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28-55 Chromosomal Abnormality in Sex Diffferentiation: Due to genetic or hormonal abnormality May cause pseudohermaphroditism Major defect is due to a phenomenon in which sex chromosomes fail to separate Gonadal dysgenesis/ Ovarian oogenesis/ Turner’s Syndrome: The gonads are rudimentary or absent 44XX 22 0 44X0 22 X OVUM ZYGOT Abnormal meiosis

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28-56 2. 44Y0 patterns: Mostly lethal 44XX 22 0 44Y0 22 Y OVUM ZYGOT Abnormal meiosis

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28-57 3. Superfemale No characteristic abnormalities 44XX 22 XX 44 xxx 22 X OVUM ZYGOT Abnormal meiosis

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28-58 4. Seminiferous tubule dysgenesis or Klinefelter: Most common Have genitalia of normal male But seminiferous tubule are abnormal High risk of mental retardation 44XX 22 0 44 xxy 22 Y OVUM ZYGOT Abnormal meiosis

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28-59 Pregnancy: As ovum is fertilized pregnancy is succeed 9 months and 10 days Physiological changes:

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28-60 Physiological changes:

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28-61 EXAMINATION OF THE FOETUS: AMNIOCENTESIS ULTRASONOGRAPHY PREGNENCY TEST

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28-62 AMNIOCENTESIS is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections, In this a small amount of amniotic fluid, which contains fetal tissues, is extracted from the amnion or amniotic sac surrounding a developing fetus, and the fetal DNA is examined for genetic abnormalities.

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28-63 2. ULTRASONOGRAPHY is an ultrasound-based diagnostic imaging technique used to visualize subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions. Obstetric sonography is commonly used during pregnancy and is widely recognized by the public.

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28-64 PREGNENCY TEST Attempts to determine whether or not a woman is pregnant. Modern pregnancy tests look for chemical markers associated with pregnancy. These markers are found in urine and blood, and pregnancy tests require sampling one of these substances. The first of these markers to be discovered, human chorionic gonadotropin (hCG), was discovered in 1930 to be produced by the trophoblast cells of the fertilised ovum (blastocyst). While hCG is a reliable marker of pregnancy, it cannot be detected until after implantation:[this results in false negatives if the test is performed during the very early stages of pregnancy.

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28-65 Test tube babies/In Vitro babies/ Laboratory baby: A sperm and egg are taken from two seperate donors. The protective shell that exists on the surface of the female egg cell. When this shell is removed, the sperm cell is allowed to fertalize the egg. After fertilization happens, the zygote is allowed to grow for a while in a nutrition solution. This mixture is placed in a test tube, hence test tube baby. After the cell cluster has reached a certain maturity, it is implanted into the surragate mother or in the same mother. This is the most risky part of the process, as the cells have to bond to the Uterus wall. After they have bonded, the process is officialy complete. After a nine month gestation period, a baby is born.

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28-66 PARTURITION/ BIRTH: Labor is the sequence of events that occur during birth. The average gestation period is 40 weeks (280 days), with a range of 37 to 42 weeks. Toward the end of gestation, the placental secretion of progesterone decreases while the estrogen level remains high, and the myometrium begins to contract weakly at irregular intervals. At this time the fetus is often oriented head down within the uterus

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28-67 Labor itself may be divided into three stages: First stage—dilation of the cervix: As the uterus contracts, the amniotic sac is forced into the cervix, which dilates (widens) the cervical opening. At the end of this stage, the amniotic sac breaks (rupture of the “bag of waters”) and the fluid leaves through the vagina, which may now be called the birth canal. This stage lasts an average of 8 to 12 hours but may vary considerably.

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28-68 Second stage—delivery of the infant. More powerful contractions of the uterus are brought about by oxytocin released by the posterior pituitary gland and perhaps by the placenta itself. If the fetus is positioned other than head down, delivery may be difficult. This is called a breech birth (the baby enters the birth canal with the buttocks or feet). and It may necessitate a cesarean section (C-section), which is delivery of the fetus through a surgical incision in the abdominal wall and uterus. For some women, the central opening in the pelvic bone may be too small to permit a vaginal delivery. Fetal distress, as determined by fetal monitoring of heartbeat for example, may also require a cesarean section.

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28-69 Third stage—delivery of the placenta (afterbirth). Continued contractions of the uterus expel the placenta and membranes, usually within 10 minutes after delivery of the infant. There is some bleeding at this time, but the uterus rapidly decreases in size, and the contractions compress the endometrium to close the ruptured blood vessels at the former site of the placenta. This is important to prevent severe maternal hemorrhage.

Blood Supply to the Uterus : 

28-70 Blood Supply to the Uterus Uterine arteries branch as arcuate arteries and radial arteries that supply the myometrium Straight & spiral branches penetrate to the endometrium spiral arteries supply the stratum functionalis their constriction due to hormonal changes starts menstrual cycle

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28-71 THANK YOU