Male Reproductive System PDF

THE REPRODUCTIVE SYSTEM DR. MARIA CRISELDA M. BONIFACIO-UY, RN, AFPAAAMMI  OVERVIEW The reproductive system appears to “slumber” until puberty, when reproductive organs become functional. Gonads or primary sex organs: TESTES and OVARIES Produce sex...

THE REPRODUCTIVE SYSTEM DR. MARIA CRISELDA M. BONIFACIO-UY, RN, AFPAAAMMI  OVERVIEW The reproductive system appears to “slumber” until puberty, when reproductive organs become functional. Gonads or primary sex organs: TESTES and OVARIES Produce sex cells or GAMETES and secrete sex hormones The reproductive role of the man is to manufacture male gametes called SPERM; woman produces female gamete called OVA (singular ovum) or eggs Fertilized egg is called a ZYGOTE —> EMBRYO —> FETUS Sex hormones play vital roles both in the development and function of the reproductive organs and in sexual behavior and drives; as well as growth and development of many other organs and tissues ANATOMY OF THE MALE REPRODUCTIVE SYSTEM TESTES Golf ball sized; approx 4cm (1.5 in) long and 2.5cm (1 in) wide Connected to the trunk via the SPERMATIC CORD Spermatic cord - is a connective tissue sheath that encloses blood vessels, nerves and the ductus deferens Tunica albuginea - is a brous connective tissue capsule, that surrounds each testis Seminiferous tubules - the actual “sperm-forming factories”; of each lobule empty sperm into another set of tubules called the RETE TESTIS - located to one side of the testis Sperm travel through the rete testis to enter the rst part of the duct system, EPIDIDYMIS Interstitial cells - produce androgens and testosterone fi fi ANATOMY OF THE MALE REPRODUCTIVE SYSTEM DUCT SYSTEM EPIDIDYMIS Cup shape, highly convoluted tube 6m (20 ft) long; posterior side of the testis First part of the male duct system Provides a temporary storage site for the immature sperm Contracts during ejaculation and expel sperm into the ductus deferens ANATOMY OF THE MALE REPRODUCTIVE SYSTEM DUCT SYSTEM DUCTUS DEFERENS/ VAS DEFERENS Runs upward from the epididymis via the spermatic cord through the inguinal canal into the pelvic cavity and arches over the superior aspect of the urinary bladder Loops medially over the ureter and descends along the posterior bladder wall Its end expands as the ampulla and then empty into the ejaculatory duct which passes through the prostate to merge with the urethra Main function is to proper live sperm from their storage sites - the epididymis and distal part of the ductus deferens - into the urethra ANATOMY OF THE MALE REPRODUCTIVE SYSTEM DUCT SYSTEM DUCTUS DEFERENS/ VAS DEFERENS VASECTOMY - cutting the vas; a minor operation that cut and tie o the ductus deferens Sperm are still producd but no longer leave the body, and eventually deteriorate and are phagocytized. A man is sterile but because of testosterone is still produced, sex drive and secondary sex characteristics are still retained ff ANATOMY OF THE MALE REPRODUCTIVE SYSTEM DUCT SYSTEM URETHRA Extends from the base of the urinary bladder to the tip of the penis Terminal part of the male duct system 3 regions 1. Prostatic urethra - surrounded by the prostate gland 2. Membranous urethra - spanning the distance from the prostate urethra to the penis 3. Spongy (penile) urethra - running within the length of the penis and opening of the body exterior via the external urethral ori ce When ejaculation occurs and sperm enter the prostatic urethra from the ejaculatory ducts the bladder sphincter constricts. fi ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN SEMINAL VESICLES Located at the base of the bladder Large hollow glands, each 6 to 7 cm Produce about 60% of seminal uid Their thick, yellowish secretion is rich in sugar (fructose), vitamin C, prostaglandins and other substances that nourish and activate the sperm passing through the tract The duct of each seminal vesicle joins that of the ductus deferens on the same side to form the ejaculatory duct Sperm and seminal uid enter the urethra together during ejaculation fl fl ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN PROSTATE A single doughnut shaped gland, about the size of peach pit It encircles the prostatic urethra just inferior to the urinary bladder Prostate uid is milky and plays a role in activating sperm During ejaculation the uid enters the urethra through several small ducts. Located immediately anterior to the rectum, its size and texture can be palpated by digital rectal examination fl fl ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN Hypertrophy of the prostate - an increase in its size independent of the body’s growth, a ects nearly every older man and strangles the urethra Makes urination di cult and enhances the risk of cystitis and kidney damage Prostatitis - in ammation of the prostate; single most common reason for a man to consult a urologist Prostate Cancer - third most prevalent cancer in men; slow growing fl ffi ff ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN BULBOURETHRAL GLANDS Are tiny, pea-sized glands inferior to the prostate gland Produce a thick, clear mucus that drains into the penile urethra This secretion is the rst to pass down the urethra when a man becomes sexually excited. It cleanses the urethra of trace of acidic urine prior to ejaculation, it serves as a lubricant during sexual intercourse fi ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN SEMEN A milky white, sticky mixture of sperm and accessory gland secretions The liquid portion acts as transport medium for nutrients and chemicals that protect the sperm and aid their movement. Mature sperm cells are streamlined cellular tadpoles containing little cytoplasm and stored nutrients The fructose in seminal vesicles secretions provide all of their energy fuel ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN SEMEN Sperm are very sluggish under acidic conditions (below pH 6) Alkalinity of semen as a whole is pH 7.2-7.6, helps neutralize the acidic environment of the female vagina (pH 3.5-4) Dilutes sperm; without it sperm motility is severly impaired Ejaculate: 2 to 5ml - each ml contains 50 - 150 million sperm < 20 million per ml makes impregnation improbable ANATOMY OF THE MALE REPRODUCTIVE SYSTEM ACCESSORY GLANDS AND SEMEN SEMEN Contains: Antibiotic chemicals - seminalplasmin, zinc, lactoferrin, defensins, prostatic acid phosphatase Relaxin - enhance sperm motility; promoting sperm capacitation, increase acrosome reaction, improving cervical mucus penetration. Enzymes - enhances sperm motility (eg Hyaluronidase, Acrosin, Proteases, PSA, Fibrolysin, Lactic dehydrogenase) Prostaglandin - inhibit immune response in the reproductive tract ANATOMY OF THE MALE REPRODUCTIVE SYSTEM EXTERNAL GENITALIA SCROTUM Is a divided sac of skin with sparse hairs that hangs outside the abdominal cavity, between the legs at the root of the penis Provides a temperature about 3 C lower than body temperature - necessary for the production of healthy sperm ANATOMY OF THE MALE REPRODUCTIVE SYSTEM EXTERNAL GENITALIA PENIS Functions to deliver sperm into the female reproductive tract Shaft Glans penis Prepuce/ Foreskin Circumcision - surgical removal of the foreskin ANATOMY OF THE MALE REPRODUCTIVE SYSTEM EXTERNAL GENITALIA Erectile tissue a spongy tissue that lls with blood during sexual excitement; surrounds the spongy urethra Causes the penis to enlarge and become rigid Erection helps the penis serve as the male organ of copulation to deliver the semen into the female reproductive tract fi  MALE REPRODUCTIVE FUNCTIONS SPERMATOGENESIS Sperm production Begins during puberty and continues throughout life A man makes millions of sperm daily Only one sperm fertilizes an egg Sperm are formed in the seminiferous tubules of the testis Spermatogonia - a primitive stem cells; found in the periphery of each tubule Goes through rapid mitotic divisions to build up the stem cell line During puberty FSH is secreted in increasing amounts by the anterior pituitary gland  MALE REPRODUCTIVE FUNCTIONS SPERMATOGENESIS A spermatogonium produces one stem cells, called a type A daughter cells and another cell, called a type B daughter cell Type A cell remains at the tubule periphery to maintain stem cell population Type B cell gets pushed toward the tubule lumen where it becomes a primary spermatocyte destined to undergo meiosis and form four sperm. Meiosis is a special type of nuclear division that occurs only in the gonads (testes and ovaries); consist of two successive division of the nucleus (meiosis I & II) instead of only one division —> results in four (instead of two) daughter cells or gametes. Gamete are called SPERMATIDS which contains Have only half as much genetic material as other body cells; haploid or n; 23 chromosomes; When the sperm and egg (which also has 23 chromosomes) unite forming the fertilized egg or zygote, the normal 2n number of 46 chromosome is reestablished and is maintained in subsequent body cells by the process of mitosis  MALE REPRODUCTIVE FUNCTIONS SPERMATOGENESIS Meiosis: dividing cells (primary and secondary spermatocytes) are pushed toward the lumen of the tubule. Spermatid of meiosis are not functional sperm; nonmotile —> undergo further physical changes, in which their excess cystoplasm is stripped away and a tail is formed Spermiogenesis - last stage of sperm development; all excess cystoplasm is slough o and 3 regions of fully formed sperm remains — head, midpiece and tail Mature sperm - has high metabolic rate and a means of propelling itself, enabling it to move long distances in a short time to get to the egg Sperm head is the nucleus and contains compacted DNA, the genetic material; anterior to the nucleus is the helmetlike ACROSOME which is produced by the Golgi apparatus and is similar to the large lysosome ff  MALE REPRODUCTIVE FUNCTIONS SPERMATOGENESIS When a sperm comes into close contact with an egg, the acrosomal membrane breaks down and releases enzyme that help the sperm penetrate the capsule of follicle cells that surround the egg Filaments which form the long tail, arise from centrioles in the midpiece. Mitochondria wrapped tightly around these laments provide the ATP needed for the rolling, one sided movements of the tail that propel the sperm along the female reproductive tract The entire process from the formation of a primary spermatocyte to release of immature sperm in the tubule lumen takes 64 to 72 days. fi  MALE REPRODUCTIVE FUNCTIONS TESTOSTERONE PRODUCTION Testosterone - produced by interstitial cells; most important hormonal product of the testes. In a male embryo small amounts of testosterone are produced to in uence embryonic development of male structures. During puberty, as the seminiferous tubules are being prodded by the FSH to produce sperm, the interstitial cells are being stimulated by luteinizing hormone (LH) Testosterone is produced continuously for the rest of a man’s life. The rising blood level of testosterone in the young man stimulates the adolescent growth spurt, prompts his reproductive organs to develop to their adult size, underlies the sex drive and causes the male secondary sex characteristics to appear. fl  MALE REPRODUCTIVE FUNCTIONS TESTOSTERONE PRODUCTION Male secondary sex characteristics include the following: Deepening of the voice as the larynx enlarges Increased hair growth all over the body, particularly in the axillary and pubic regions and on the face Enlargement of skeletal muscles to produce the heavier muscle mass typical of the male physique Increased heaviness of the skeleton due to bone growth in both size and density  ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM OVARIES The primary female reproductive organs Paired; resemble almonds Ovarian follicles - tiny saclike structures; Each follicle consist of an immature egg called an OOCYTE The follicle enlarges and develops a uid- lled central region called an antrum. Graa an / vesicular follicle - mature follicle and the developing egg is ready to be ejected from the ovary —> ovulation After ovulation — the ruptured follicle is transformed into corpus luteum Ovulation occurs every 28 days fi fl fi ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM OVARIES Suspensory ligament - secures both the ovaries and uterus to the lateral walls of the pelvis Ovarian ligament - anchors the ovary to the uterus medially Broad ligament - a fold of peritoneum that encloses the ovaries, uterus and fallopian tubes ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM UTERINE TUBES/FALLOPIAN TUBES Form the initial part of the duct system Receive the ovulated oocyte and provide a site where fertilization can occur 10cm (4 in) long and extend medial from the ovary to empty into the superior region of the uterus There is little or no actual contact the between uterine tubes and the ovaries  ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM UTERINE TUBES/FALLOPIAN TUBES Four parts (lateral to medial) 1. Fimbriae - nger-like, ciliated projections which capture the ovum from the surface of the ovary 2. Infundibulum - funnel shaped opening near the ovary to which the mbrae are attached 3. Ampulla - widest section; where fertilization occurs 4. Isthmus - narrow section; connects the ampulla to the uterine cavity fi fi ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM UTERINE TUBES/FALLOPIAN TUBES Because the journey to the uterus takes 3 to 4 days and the oocyte is viable for at most 24 hours after ovulation, the usual site of fertilization is the uterine tube. To reach the oocyte, the sperm must swim upward through the vagina and uterus to reach the uterine tubes. ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM UTERUS Located in the pelvis between the urinary bladder and rectum A hollow organ that functions to receive, retain and nourish a fertilized egg eventually to aid in childbirth Nulliparous woman - a woman who has never given birth; the uterus is about the size and shape of a pear During pregnancy - uterus increases tremendously in size and during the latter part of pregnancy can be felt well above the umbilicus ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM UTERUS Suspended in the pelvis by the broad ligament Anchored anteriorly by the round ligament; posteriorly by the uterosacral ligament Parts: 1. Body 2. Fundus - rounded region superior to the entrance of the uterine tubes 3. Cervix - narrow outlet; protrudes inferiorly into the vagina ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM UTERUS 3 layers: 1. Endometrium - inner layer; where implantation occurs; if fertilization does not occur the endometrial lining sloughs o periodically — about every 28 days — menstruation 2. Myometrium - bulky middle layer; composed of interlacing bundles of smooth muscles; plays an active role during childbirth when it contracts rhythmically to force the baby out 3. Perimetrium/ visceral peritoneum - outermost layer ff ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM VAGINA A thin-walled tube 8 to 10 cm (3-4in) long Lies between the bladder and rectum Extends from the cervix to the body exterior Often called the birth canal Provides a passageway for the delivery of an infant and for the menstrual ow to leave the body It is the female organ of copulation fl ANATOMY OF THE FEMALE REPRODUCTIVE SYSTEM DUCT SYSTEM VAGINA Distal end is partially closed by a thin fold of the mucosa called the HYMEN HYMEN - is very vascular and tends to bleed when it is ruptured during the rst sexual intercourse. fi  EXTERNAL GENITALIA and FEMALE PERINEUM Aka the VULVA Mons pubis A fatty, rounded area overlying the pubic symphysis After puberty is it covered with pubic hair Labia majora - two elongated hair covered skin folds that encloses the labia minora Labia minora - two delicate and hair free fold  EXTERNAL GENITALIA and FEMALE PERINEUM Vestibule - a region enclosed by the labia majora which contains the external opening of the urethra Clitoris - anterior ro the vestibule; a small, protruding structure that corresponds to the male penis; hooded by a prepuce and is composed of sensitive eretile tissue that becomes swollen with blood during sexual excitement Greater vestibular glands - a pair of mucus producing glands, ank the vagina, one on each side; lubricates the distal end of the vagina during intercourse Perineum - the diamond shaped region between the anterior end of the labial folds, the anus posteriorly and the ischial tuberosities. fl  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES The total supply of eggs that a female can release is already determined by the time she is born Female’s reproductive ability begins during puberty, heralded by the beginning of her menstrual cycle (menarche) and ends in her fties. Menopause - a period in which a woman’s reproductive capability ends fi  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE Ova (female gametes) are produced by OOGENESIS In the developing female fetus: OOGONIA - female stem cell — multiply rapidly to increase their number producing daughter cells called PRIMARY OOCYTES Primary oocyte push into the ovary connective tissue — become surrounded by a single layer of cells to ultimately form the PRIMORDIAL FOLLICLES — grow to become PRIMARY FOLLICLES  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE By birth: the oogonia no longer exist and a female’s lifetime supply of primary oocytes (approx 1 to 2 million of them) is already in place in the ovarial follicles, awaiting the chance to undergo meiosis to produce functional eggs The primary oocyte remain dormant until puberty At 10-14 years of age the primary oocytes decrease to about 400,00 as a result of programmed cell death  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE At puberty: the anterior pituitary gland begins to release FSH which stimulates a small number of primary follicles to grow and mature each month and ovulation begins to occur each month 400,000 oocytes remain; small number of oocyte are activated each month Ovarian cycle - is the cyclic changes that occur monthly in the ovary The reproductive life of a female is about 40 years (from 11 to approx 51)  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE FSH stimulates a follicle to grow larger, it accumulates uid in the central chamber called the ANTRUM and the primary oocyte is contains replicates its chromosomes and begins meiosis The rst meiotic division produces two cells that are very dissimilar in size: the larger cell is a SECONDARY OOCYTE and the smaller cell is a POLAR BODY fl fi  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE FSH stimulates a follicle to grow larger, it accumulates uid in the central chamber called the ANTRUM and the primary oocyte is contains replicates its chromosomes and begins meiosis The rst meiotic division produces two cells that are very dissimilar in size: the larger cell is a SECONDARY OOCYTE and the smaller cell is a POLAR BODY Vesicular follicle contains a secondary oocyte and protrudes from the external surface of the ovary Follicle development to this stage takes about 14 days and ovulation occurs at just about that time in response to the burstlike release of luteinizing hormone fi fl  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE The ovulated secondary oocyte is still surrounded by its follicle cell capsule now called the corona radiata Mittelschmertz - a twinge of abdominal pain in the lower abdomen when ovulation occurs; cause is unknown but may include intense stretching of the ovarian wall leading up to ovulation and irritation of the peritoneum by the small amout of blood or uid released by the ruptured follicle. fl  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES OOGENESIS and the OVARIAN CYCLE LH - major role in triggering ovulation and causes the ruptured follicle to transform into a hormone producing structure called the COPRUS LUTEUM If the secondary oocyte is fertilized by a sperm, the oocyte quickly completes the second meiotic division that produces the ovum and another polar body Once the ovum is formed, its 23 chromosome are combined with those of the sperm to form the ZYGOTE Meiosis in females yields only one functional ovum and three tiny polar bodies  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES HORMONE PRODUCTION by the OVARIES ESTROGEN produced by the follicle cells of the growing and matured follicles Causes the appearance of secondary sex characteristics Has metabolic e ects: maintain low total blood cholesterole levels and facilitate calcium ion uptake which sustains bone density ff  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES HORMONE PRODUCTION by the OVARIES Secondary sex characteristics 1. Enlargement of the accessory organs of the female reproductive system (uterine tubes,uterus, vagina, external genitals) 2. Development of the breasts 3. Appearance of axillary and pubic hair 4. Increased deposits of fat beneath the skin in general, and particularly in the hips and breasts 5. Widening and lightening of the pelvis 6. Onset of menses, or the menstrual cycle  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES HORMONE PRODUCTION by the OVARIES Progesterone Second ovarian hormone Produced by the glandular corpus luteum Corpus luteum stops producing hormones by 10 to 14 days after ovulation Major e ects helps maintain the pregnacy and prepare breasts for milk production The main source of production after the second month is the placenta ff  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES UTERINE (MENSTRUAL) CYCLE Is a series of cyclic changes that the endometrium (mucosa of the uterus) goes through each month as it responds to changing blood levels of ovarian hormones The cyclic production of estrogens and progesterone by the ovaries is regulated by the anterior pituitary gonadotropic hormones, FSH and LH. The ovarian and the uterine cycles are about 28 days long. Ovulation typically occurs midway in the cycles, on or about day 14.  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES UTERINE (MENSTRUAL) CYCLE Three phases: Day 0-4: Menstrual phase The super cial functional layer of the thick endometrial lining of the uterus is sloughing o from the uterine wall The detached tissues and blood pass through the vagina as menstrual ow (period) for 3 to 5 days Average blood loss during this period is 50 to 150ml By day 4, the growing ovarial follicles begin to produce more estrogen fi fl ff  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES UTERINE (MENSTRUAL) CYCLE Three phases: Day 5 - 14: Proliferative phase Stimulated by a rising level of estrogens produced by the growing follicles of the ovaries, the basal layer of the endometrium regenerates the functional layer, glands form in it, and the endometrial blood supply increases. endometrium becomes velvety, thick, and well vascularized Ovulation occurs in the ovary at the end of this stage in response to the sudden surge of LH  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES UTERINE (MENSTRUAL) CYCLE Three phases: Day 14 - 28: Secretory phase A rising level of progesterone production by the corpus luteum acts on the estrogen-primed endometrium and increases its blood supply Progesterone also causes the endometrial glands to grow and begin secreting nutrients into the uterine cavity.  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES UTERINE (MENSTRUAL) CYCLE If fertilization does occur, the embryo produces a hormone very similar to LH that causes the corpus luteum to continue producing its hormones until the placenta can take over. If fertilization does not occur, the corpus luteum begins to degenerate toward the end of this period as the LH blood level declines. Lack of ovarian hormone in the blood causes the blood vessels supplying the functional layer of the endometrium to go into spams and kink —> stage of menses begin again  FEMALE REPRODUCTIVE FUNCTIONS AND CYCLES UTERINE (MENSTRUAL) CYCLE Classic cycle: 28 days Shortest is 21 days Longest is 40 days Only one interval is fairly constant in all females--the time from ovulation to the beginning of menses is almost always 14 or 15 days  MAMMARY GLANDS Are present in both sexes but functional only to women Stimulation by female sex hormones, especially estrogens, causes the female mammary glands to increase in size at puberty. Are modi ed sweat glands that are part of the skin contained within a rounded skin-covered breast anterior to the pectoral muscles. Areola - pigmented area inferior to the center of each breast Nipple fi  MAMMARY GLANDS Each gland consist of 15 to 25 lobes that radiate around the nipple The lobes are padded and separated from one another by connective tissue and fat Within each lobe are smaller chambers called lobules which contains clusters of ALVEOLAR GLANDS that produce milk when a woman is lactating Milk produced by the alveolar glands exits each lobule by passing into LACTIFEROUS DUCTS which open to the outside at the nipple. LACTIFEROUS SINUS - dilated region just deep to the areola where milk accumulates during nursing  PREGNANCY AND EMBRYONIC DEVELOPMENT Pregnancy - refers to events that occur from the time of fertilization (conception) until birth. Conceptus - developing o spring Gestation period - which extends by convention from the last menstrual period (a date the woman is likely to remember) until birth, approximately 280 days. Embryonic period - from fertilization through 8 weeks; the conceptus is called an EMBRYO Fetal period - from week 9 through birth; the conceptus is called FETUS ff  PREGNANCY AND EMBRYONIC DEVELOPMENT ACCOMPLISHING FERTILIZATION For fertilization to occur, a sperm must reach the ovulated secondary oocyte Oocyte is viable for 12 - 24 hours after ovulation Sperm retain their fertilizing power within the female reproductive tract for up to 5 days after ejaculation for fertilization to occur, sexual intercourse must occur no more than 2 days before ovulation and no later than 24 hours after. At this point, the oocyte is approximately one-third of the way down the uterine tube.  PREGNANCY AND EMBRYONIC DEVELOPMENT ACCOMPLISHING FERTILIZATION It takes 1 to 2 hours for sperm to complete the journey up the female duct system into the uterine tubes, even though they are only about 12 cm (5 inches) away. However, millions of sperm leak out of the vagina, and of those remaining, millions more are destroyed by the vagina's acidic environment. Only a few hundred to a few thousand sperm make it to the egg's vicinity.  PREGNANCY AND EMBRYONIC DEVELOPMENT ACCOMPLISHING FERTILIZATION When the swarming sperm reach the oocyte, their cell surface hyaluronidase enzymes break down the "cement" that holds the follicle cells of the corona radiata together around the oocyte. Thousand of sperm undergo the acrosomal reaction in which the acrosome membranes breakdown, releasing enzymes that digest holes in the surrounding oocyte membrane When the membrane is weakened and a single sperm makes contact with one of the oocytes membrane receptors for sperm the head of the sperm fuses with the oocyte membrane and the snakelike sperm contents enter the oocyte cytoplasm  PREGNANCY AND EMBRYONIC DEVELOPMENT ACCOMPLISHING FERTILIZATION Fertilization occurs at the moment the genetic material of a sperm combines with that of an ovum to form a fertilized egg, or zygote, with a complete set of 46 chromosomes. The zygote represents the rst cell of the new individual. fi  PREGNANCY AND EMBRYONIC DEVELOPMENT EVENTS OF EMBRYONIC AND FETAL DEVELOPMENT Zygote begin to undergo rapid mitotic cell division forming rst two cells then four and so on Cleavage is the early stage of embryonic development; provides a large number of cells to serve as building blocks for constructing the embryo Day 3: the developing embryo reaches the uterus and becomes a MORULA - a tiny ball of 16 cells The embryo oats free in the uterine cavity, temporarily using the uterine secretions for nutrition The embryo continues to develop until it has about 100 cells and then it hollows out to form a ball-like structure called a BLASTOCYST fl fi  PREGNANCY AND EMBRYONIC DEVELOPMENT EVENTS OF EMBRYONIC AND FETAL DEVELOPMENT Blastocyst secretes an LH - like hormone called HUMAN CHORIONIC GONADOTROPIN (hCG) - which stimulates the corpus luteum of the ovary to continue producing its hormones has two important functional area: TROPHOBLAST - which forms the large uid lled sphere INNER CELL MASS - a small cluster of cells on one side fl fi  PREGNANCY AND EMBRYONIC DEVELOPMENT EVENTS OF EMBRYONIC AND FETAL DEVELOPMENT Day 7 after ovulation Implantation begins Blastocysts has attached to the endometrium The 3 primary germ layers are being formed from the inner cells mass ECTODERM - will become the nervous system and epidermis ENDODERM - forms mucosae and associated glands MESODERM - the rest of the body  PREGNANCY AND EMBRYONIC DEVELOPMENT EVENTS OF EMBRYONIC AND FETAL DEVELOPMENT Day 14 after ovulation Implantation has completed and uterine mucosa has grown over the burrowed in embryo After implantation: TROPHOBLAST develops projections called CHORIONIC VILLI - which combine with the tissues of the uterus to form the placenta. Amnion - a uid lled sac that surrounds the embryonic body; it is attached to the placenta by the umbilical cord fl fi  PREGNANCY AND EMBRYONIC DEVELOPMENT EVENTS OF EMBRYONIC AND FETAL DEVELOPMENT By the 3rd week The placenta is functioning to deliver nutrients and oxygen to and remove wastes from the embryonic blood By the 2nd month of pregnancy The placenta has become a endocrine organ and is producing estrogen, progesterone and other hormones that help maintain the pregnancy The corpus luteum becomes inactive and degenerates  PREGNANCY AND EMBRYONIC DEVELOPMENT EVENTS OF EMBRYONIC AND FETAL DEVELOPMENT By the 8th week of embryonic development Organogenesis is done By the 9th week the major activities are growth and organ specialization, accompanied by changes in body proportions. the developing fetus grows from a crown-to-rump length of about 3 cm and a weight of approximately 1 g to about 36 cm (14 inches) and 2.7 to 4.1 kg (6 to 10 pounds) or more.  PREGNANCY AND EMBRYONIC DEVELOPMENT EFFECTS OF PREGNANCY ON THE MOTHER Anatomical Changes Physiologic Changes Gastrointestinal system: nausea; heartburn Urinary system: produce more urine; frequent urination, more urgent and sometime uncontrollable -> stress incontinence Respiratory system: nasal stu ness, occasional nosebleeds; vital capacity and RR increases; residual volume declines; dyspnea CVS: blood volume increases 25 to 40%; blood pressure and pulse rise and increase cardiac output by 20 to 40%; swollen ankles and feet ffi  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Parturition is is the culmination of pregnancy. It usually occurs within 15 days of the calculated due date (which is 280 days from the last menstrual period) Labor - is the series of events that expel the infant from the uterus  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Initiation of Labor Estrogen reach their highest level on the last few weeks of pregnancy which causes the myometrium form oxytocin receptors and interferes with progesterone’s quieting in uence on the uterine muscle —> which causes BRAXTON HICKS CONTRACTIONS - weak, irregular uterine contractions - false labor Fetus cells begin to produce oxytocin —> stimulates the placenta to release prostaglandins —> stimulate more frequent and powerful contractions of the uterus fl  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Initiation of Labor The combined e ects of rising levels of oxytocin and prostaglandins initiate the rhythmic, expulsive contractions of true labor. To prevent premature birth antiprostaglandin drugs can inhibit labor. ff  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Stages of Labor Stage 1: Dilation stage is the time from the appearance of true contractions until the cervix is fully dilated by the baby's head the contractions become more vigorous and more rapid, and, as the infant's head is forced against the cervix with each contraction, the cervix begins to soften, becomes thinner (e aces), and dilates. Amnion ruptures releasing the amniotic uid Longest stage of labor; last for 6 to 12 hours or more fl ff  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Stages of Labor Stage 2: Expulsion Stage Is the period from full dilation to delivery of the infant. The infant passes through the cervix and vagina to the outside of the body. The mother experiencing natural childbirth (that is, undergoing labor without local anesthesia) has an increasing urge to push, or bear down, with the abdominal muscles. Last for about 2 hours; 50 mins in a rst birth; 20 mins in subsequent births fi  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Stages of Labor Stage 2: Expulsion Stage Vertex position (head rst), the skull acts as wedge to dilate the cervix. The head- rst presentation also allows the baby to be suctioned free of mucus and to breathe even before it has completely exited from the birth canal. Once the head has been delivered, the rest of the baby's body is delivered much more easily. After birth, the umbilical cord is clamped and cut. In breech (buttocks- rst) presentations and other nonvertex presentations, these advantages are lost and delivery is often much more di cult, sometimes requiring the use of forceps or a vacuum extractor fi fi fi ffi  PREGNANCY AND EMBRYONIC DEVELOPMENT CHILDBIRTH Stages of Labor Stage 3: Placental Stage Delivery of the placenta Accomplished within 15 mins after birth of the infant All placental fragments must be removed to prevent continued uterine bleeding after birth (postpartum bleeding). DEVELOPMENTAL ASPECT OF THE REPRODUCTIVE SYSTEM Sexual di erentiation begin at 8 weeks of embryonic development Puberty - between 10 - 15 years old Budding beasts is apparent by age 11 Menarche - rst menstrual period; occurs 2 years after budding Menopause - occurs between the ages of 46 to 54 ff fi  READ MORE ON THE DEVELOPMENTAL ASPECT OF THE REPRODUCTIVE SYSTEM “May the odds be ever in your favor” THANK YOU and MAY GOD BLESS YOU