Dr.amin Embryology

EMBRYOLOGYEMBRYOLOGY

AHMAD AMINUDDINAHMAD AMINUDDIN

GAMETOGENESISGAMETOGENESIS

GAMETES ARE DERIVED FROM PRIMORDIAL GAMETES ARE DERIVED FROM PRIMORDIAL GERM CELLS THAT ARE FORMED IN THE GERM CELLS THAT ARE FORMED IN THE EPIBLAST DURING 2EPIBLAST DURING 2NDND WEEK AND THAT WEEK AND THAT MOVE TO THE WALL OF THE YOLK MOVE TO THE WALL OF THE YOLK SAC.MITOTIC DIVISION.SAC.MITOTIC DIVISION.

DURING 4DURING 4THTH WEEK PRIMORDIAL GERM CELLS WEEK PRIMORDIAL GERM CELLS BEGIN TO MIGRATE FROM YOLK SAC BEGIN TO MIGRATE FROM YOLK SAC TOWARD THE DEVELOPING GONADS, TOWARD THE DEVELOPING GONADS, ARRIVE BY THE END OF 5ARRIVE BY THE END OF 5THTH WEEK. MITOTIC WEEK. MITOTIC DIVISION.DIVISION.

CLINICAL CORRELATESCLINICAL CORRELATES

TERATOMAS TERATOMAS

are tumors of disputed origin that often are tumors of disputed origin that often contain a variety of tissues, such as bone, hair, contain a variety of tissues, such as bone, hair, muscle, gut epithelia, and others.muscle, gut epithelia, and others.

It is thought that these tumors arise from a It is thought that these tumors arise from a pluripotent stem cells that can differentiate in pluripotent stem cells that can differentiate in to any of the three germ layers or their to any of the three germ layers or their derivates.derivates.

THE CHROMOSOME THEORY THE CHROMOSOME THEORY OF INHERITANCEOF INHERITANCE

HUMAN HAVE APPROXIMATELY 35.OOO HUMAN HAVE APPROXIMATELY 35.OOO GENES ON 46 CHROMOSOMES.GENES ON 46 CHROMOSOMES.

GENES ON THE SAME CHROMOSOME TEND GENES ON THE SAME CHROMOSOME TEND TO BE INHERITED TOGETHER AND SO ARE TO BE INHERITED TOGETHER AND SO ARE KNOWN AS LINKED GENES.KNOWN AS LINKED GENES.

IN SOMATIC CELLS, CHROMOSOMES APPEAR IN SOMATIC CELLS, CHROMOSOMES APPEAR AS 23 HOMOLOGOUS PAIRS TO FORM THE AS 23 HOMOLOGOUS PAIRS TO FORM THE DIPLOID NUMBER OF 46.DIPLOID NUMBER OF 46.

THERE ARE 22 PAIRS OF THE AUTOSOMES, THERE ARE 22 PAIRS OF THE AUTOSOMES, AND ONE PAIR OF SEX CHROMOSOMES.AND ONE PAIR OF SEX CHROMOSOMES.

SEX PAIR : XX - female.SEX PAIR : XX - female. XY - male.XY - male.

MITOSISMITOSIS

MITOSIS IS THE PROCESS WHEREBT MITOSIS IS THE PROCESS WHEREBT ONE CELL DIVIDES, GIVING RISE TO ONE CELL DIVIDES, GIVING RISE TO TWO DAUGHTER CELLS THAT ARE TWO DAUGHTER CELLS THAT ARE GENETICALLY IDENTICAL TO THE GENETICALLY IDENTICAL TO THE PARENT CELL.PARENT CELL.

EACH DAUGHTER CELL RECEIVES THE EACH DAUGHTER CELL RECEIVES THE COMPLETE COMPLEMENT OF 46 COMPLETE COMPLEMENT OF 46 CHROMOSOMES.CHROMOSOMES.

MEIOSISMEIOSIS

MEIOSIS IS THE CELL DIVISISON THAT MEIOSIS IS THE CELL DIVISISON THAT TAKE PLACE IN THE GERM CELLS TO TAKE PLACE IN THE GERM CELLS TO GENERATE MALE AND FEMALE GENERATE MALE AND FEMALE GAMETES, SPERM AND EGG CELLS.GAMETES, SPERM AND EGG CELLS.

MEIOSIS REQUIRES TWO CELL MEIOSIS REQUIRES TWO CELL DIVISION ;DIVISION ;

- MEIOSIS I.- MEIOSIS I.

- MEIOSIS II.- MEIOSIS II.

CHROMOSOMAL CHROMOSOMAL ABNORMALITIESABNORMALITIES

NUMERICAL ABNORMALITIESNUMERICAL ABNORMALITIES

- ORIGINATE DURING MEIOTIC AND - ORIGINATE DURING MEIOTIC AND

MITOTIC DIVISIONS.MITOTIC DIVISIONS.

- THERE ARE :- THERE ARE :

- NONDISJUNCTION.- NONDISJUNCTION.

- TRANSLOCATIONS.- TRANSLOCATIONS.

TRANSLOCATIONSTRANSLOCATIONS

NUMERICAL NUMERICAL ABNORMALITIESABNORMALITIES

TRISOMY 21 ( DOWN SYNDROME ).TRISOMY 21 ( DOWN SYNDROME ). TRISOMY 18.TRISOMY 18. TRISOMY 13.TRISOMY 13. KLINEFELTER SYNDROME.KLINEFELTER SYNDROME. TURNER SYNDROME.TURNER SYNDROME. TRIPLE X SYNDROME.TRIPLE X SYNDROME.

STUCTURAL ABNORMALITIESSTUCTURAL ABNORMALITIES

CRI-DU-CHAT SYNDROME.CRI-DU-CHAT SYNDROME. - delition of the short arm of chromosome 5.- delition of the short arm of chromosome 5. ANGELMAN SYNDROME.ANGELMAN SYNDROME. - inherited on the maternal chromosome- inherited on the maternal chromosome PRADER-WILLI SYNDROME.PRADER-WILLI SYNDROME. - inherited on the paternal chromosome.- inherited on the paternal chromosome. MILLER-DIEKER SYNDROME.MILLER-DIEKER SYNDROME. - inherited from either parent.- inherited from either parent. VELOCARDIOFACIAL SYNDROME.VELOCARDIOFACIAL SYNDROME. FRAGILE X SYNDROME.FRAGILE X SYNDROME.

GENE MUTATIONSGENE MUTATIONS

IN BORN ERROR METABOLISMIN BORN ERROR METABOLISM

- PHENYLKETONURIA.- PHENYLKETONURIA.

- HOMOCYSTINURIA.- HOMOCYSTINURIA.

- GALACTOSEMIA.- GALACTOSEMIA.

FREQUENTLY ACCOMPANIED BY OR FREQUENTLY ACCOMPANIED BY OR

CAUSE VARIOUS DEGREES OF MENTAL CAUSE VARIOUS DEGREES OF MENTAL

RETARDATIONRETARDATION

OOGENESISOOGENESIS

MATURATION OF OOCYTES BEGINS MATURATION OF OOCYTES BEGINS BEFORE BIRTH.BEFORE BIRTH.

PRIMORDIAL GERM CELLS IN THE PRIMORDIAL GERM CELLS IN THE GONAD OF A GENETIC FEMALE, GONAD OF A GENETIC FEMALE, DIFFERENTIATE IN TO OOGONIA.DIFFERENTIATE IN TO OOGONIA.

BY THE END OF THE 3BY THE END OF THE 3RDRD MONTH ARE MONTH ARE ARANGED IN CLUSTER, SURROUNDED ARANGED IN CLUSTER, SURROUNDED BY A LAYER OF FLAE EPITHELIAL BY A LAYER OF FLAE EPITHELIAL CELL, KNOWN AS FOLLICULAR CELLS.CELL, KNOWN AS FOLLICULAR CELLS.

THE MAJORITY OF OOGONIA THE MAJORITY OF OOGONIA CONTINUE TO MITOSISCONTINUE TO MITOSIS

BY THE 5BY THE 5THTH MONTH ARE 7 MILLION, AT MONTH ARE 7 MILLION, AT THIS TIME CELL DEATH BEGINS.THIS TIME CELL DEATH BEGINS.

PRIMARY OOCYTES IN PROPHASE OF PRIMARY OOCYTES IN PROPHASE OF MEIOSIS I , SURROUNDED BY FLAT MEIOSIS I , SURROUNDED BY FLAT EPITHELIAL CELLS IS KNOWN AS EPITHELIAL CELLS IS KNOWN AS PRIMORDIAL FOLLICLE.PRIMORDIAL FOLLICLE.

NEAR THE TIME OF BIRTH ALL NEAR THE TIME OF BIRTH ALL PRIMARY OOCYES, ENTER THE PRIMARY OOCYES, ENTER THE DIPLOTENE STAGE.DIPLOTENE STAGE.

MATURATION OF OOCYTES MATURATION OF OOCYTES CONTINUES AT PUBERTYCONTINUES AT PUBERTY

PRIMARY OOCYTES REMAIN ARRESTED IN PRIMARY OOCYTES REMAIN ARRESTED IN PROPHASE AND DO NOT FINISH THEIR FIRST PROPHASE AND DO NOT FINISH THEIR FIRST MEIOTIC DIVISION BEFORE PUBERTY IS MEIOTIC DIVISION BEFORE PUBERTY IS REACHED.REACHED.

AT BIRTH THERE ARE PRIMARY OOCYTES ; AT BIRTH THERE ARE PRIMARY OOCYTES ; 600.000 – 800.000.600.000 – 800.000.

DURING CHILDHOOD MOST OOCYTES DURING CHILDHOOD MOST OOCYTES BECOME ATRETIC.BECOME ATRETIC.

AT THE BEGINNING OF PUBERTY;400000.AT THE BEGINNING OF PUBERTY;400000. < 500 WILL BE OVULATED.< 500 WILL BE OVULATED.


AT PUBERTY GROWING FOLLICLE PASSING AT PUBERTY GROWING FOLLICLE PASSING THROUGH 3 STAGESTHROUGH 3 STAGES

- PRIMARY OR PREANTRAL.- PRIMARY OR PREANTRAL.

- SECONDARY OR ANTRAL.- SECONDARY OR ANTRAL.

- PREOVULATORY ( GRAFIAN FOLLICLE )- PREOVULATORY ( GRAFIAN FOLLICLE ) ONLY ONE FOLLICLE REACHES MATURITY.ONLY ONE FOLLICLE REACHES MATURITY. WHEN SECONDARY FOLLICLE IS MATURE A WHEN SECONDARY FOLLICLE IS MATURE A

SURGE IN LUTEINIZING HORMON INDUCE SURGE IN LUTEINIZING HORMON INDUCE THE PROOVULATORY GROWTH PHASE.THE PROOVULATORY GROWTH PHASE.


MEIOSIS I IS COMPLETED , RESULTIG IN MEIOSIS I IS COMPLETED , RESULTIG IN FORMATION OF TWO DAUGHTER CELLS OF FORMATION OF TWO DAUGHTER CELLS OF UNEQUAL SIZE, SECONDARY OOCYTE AND UNEQUAL SIZE, SECONDARY OOCYTE AND FIRST POLAR BODY.FIRST POLAR BODY.

ENTER MEIOSIS II BUT ARREST IN ENTER MEIOSIS II BUT ARREST IN METAPHASE APPROXIMATELY 3 HOURS METAPHASE APPROXIMATELY 3 HOURS BEFORE OVULATION.BEFORE OVULATION.

MEIOSIS II IS COMPLETED ONLY IF THE MEIOSIS II IS COMPLETED ONLY IF THE OOCYTE IS FERTILIZED.OOCYTE IS FERTILIZED.

THE FIRST POLAR BODY ALSO UNDERGO THE FIRST POLAR BODY ALSO UNDERGO DIVISION.DIVISION.

SPERMATOGENESISSPERMATOGENESIS

MATURATION OF SPERM BEGINS AT MATURATION OF SPERM BEGINS AT PUBERTY.PUBERTY.

SHORTLY BEFORE PUBERTY, THE SEX CORD SHORTLY BEFORE PUBERTY, THE SEX CORD BECOME THE SEMINIFEROUS TUBULES.BECOME THE SEMINIFEROUS TUBULES.

AT ABOUT THE SAME TIME PRIMORDIAL AT ABOUT THE SAME TIME PRIMORDIAL GERM CELLS GIVE RISE TO GERM CELLS GIVE RISE TO SPERMATOGONIAL STEM CELLS.SPERMATOGONIAL STEM CELLS.

AT REGULAR INTERVAL, CELLS EMERGE AT REGULAR INTERVAL, CELLS EMERGE FROM THIS STEM CELL TO FORM TYPE A FROM THIS STEM CELL TO FORM TYPE A SPERMATOGONIA.SPERMATOGONIA.

SPERMATOGENESIS SPERMATOGENESIS REGULATIONREGULATION

REGULATED BY L.H. PRODUCTION BY THE REGULATED BY L.H. PRODUCTION BY THE PITUITARY.PITUITARY.

L.H BINDS TO RECEPTOR ON LEIDIG CELLS L.H BINDS TO RECEPTOR ON LEIDIG CELLS AND STIMULATES TESTOSTERON AND STIMULATES TESTOSTERON PRODUCTION.PRODUCTION.

TESTOSTERON BINDS TO SERTOLI CELLS TO TESTOSTERON BINDS TO SERTOLI CELLS TO PROMOTE SPERMATOGENESIS.PROMOTE SPERMATOGENESIS.

F.S.H. BINDS TO SERTOLI CELLS STIMULATES F.S.H. BINDS TO SERTOLI CELLS STIMULATES TESTICULAR FLUID PRODUCTION AND TESTICULAR FLUID PRODUCTION AND SYNTHESIS OF INTRACELLULAR ANDROGEN SYNTHESIS OF INTRACELLULAR ANDROGEN RECEPTOR PROTEIN.RECEPTOR PROTEIN.

SPERMIOGENESISSPERMIOGENESIS THE SERIES OF CHANGES RESULTING IN THE THE SERIES OF CHANGES RESULTING IN THE

TRANSFORMATION OF SPERMATIDS INTO TRANSFORMATION OF SPERMATIDS INTO SPERMATOZOA.SPERMATOZOA.

THE CHANGES INCLUDE ;THE CHANGES INCLUDE ; - FORMATION OF THE ACROSOME.- FORMATION OF THE ACROSOME. - CONDENSATION OF THE NUCLEUS.- CONDENSATION OF THE NUCLEUS. - FORMATION OF NECK, MIDDLE PIECE, - FORMATION OF NECK, MIDDLE PIECE, AND TAIL.AND TAIL. - SHEDDING OF MOST OF THE CYTOPLASM.- SHEDDING OF MOST OF THE CYTOPLASM. THE TIME REQUIRED ; 74 DAYS, AND THE TIME REQUIRED ; 74 DAYS, AND

APPROXIMATELY 300 MILLION SPERM CELLS APPROXIMATELY 300 MILLION SPERM CELLS ARE PRODUCED DAILY.ARE PRODUCED DAILY.

ABNORMAL GERM CELLSABNORMAL GERM CELLS

THE FIRST WEEK OF THE FIRST WEEK OF DEVELOPMETDEVELOPMET

0VULATION TO IMPLANTATION0VULATION TO IMPLANTATION

OVARIAN CYCLEOVARIAN CYCLE

THESE SEXUAL CYCLES ARE CONTROL LED THESE SEXUAL CYCLES ARE CONTROL LED BY THE HYPOTHALAMUS.BY THE HYPOTHALAMUS.

GONADOTROPIN-RELEASING HORMON GONADOTROPIN-RELEASING HORMON PRODUCED BY THE HYPOTHALAMUS, ACTS PRODUCED BY THE HYPOTHALAMUS, ACTS ON THE CELLS OF THE ANTERIOR PITUITARY ON THE CELLS OF THE ANTERIOR PITUITARY GLAND, WICH IN TURN SECRETE GLAND, WICH IN TURN SECRETE GONADOTROPIN.GONADOTROPIN.

THESE HORMONES, FOLLICLE-STIMU LATING THESE HORMONES, FOLLICLE-STIMU LATING HORMON ( FSH ) AND LUTEINIZING HORMON HORMON ( FSH ) AND LUTEINIZING HORMON ( LH ), STIMULATE AND CONTROL CYCLIC ( LH ), STIMULATE AND CONTROL CYCLIC CHANGE IN THE OVARYCHANGE IN THE OVARY

ESTROGENESTROGEN

PRODUCED BY : GRANULOSA CELLS.PRODUCED BY : GRANULOSA CELLS. THECA CELLS. THECA CELLS. FUNCTIONS :FUNCTIONS : - cause the uterine endometrium to enter the - cause the uterine endometrium to enter the follicular or proliferative phase.follicular or proliferative phase. - cause thining of the cervical mucus to allow - cause thining of the cervical mucus to allow passage of sperm.passage of sperm. - stimulate the pituitary gland to secrete LH- stimulate the pituitary gland to secrete LH

LUTEINIZING HORMONELUTEINIZING HORMONE

AT MIDCYCLE, THERE IS AN LH SURGE AT MIDCYCLE, THERE IS AN LH SURGE THAT :THAT :

- elevates concentrations of maturation-promo - elevates concentrations of maturation-promo ting factor, causing oocytes to complete meio ting factor, causing oocytes to complete meio sis I and initiate meiosis II.sis I and initiate meiosis II. - stimulates production of progesterone by - stimulates production of progesterone by follicular stromal cells ( luteinization ).follicular stromal cells ( luteinization ). - causes follicular rupture and ovulation.- causes follicular rupture and ovulation.

OVULATIONOVULATION AN ABRUPT INCREASE IN L.H. THAT CAUSE THE PRIMARY AN ABRUPT INCREASE IN L.H. THAT CAUSE THE PRIMARY

OOCYTE TO COMPLETE MEIOSIS I AND THE FOLLICLE TO OOCYTE TO COMPLETE MEIOSIS I AND THE FOLLICLE TO ENTER THE PREOVULATO RY STAGE.ENTER THE PREOVULATO RY STAGE.

MEIOSIS II IS ALSO INITIATED, BUT THE OOCYTE IS ARRESTED MEIOSIS II IS ALSO INITIATED, BUT THE OOCYTE IS ARRESTED IN METAPHASE APPROXIMATELY 3 HOURS BEFORE IN METAPHASE APPROXIMATELY 3 HOURS BEFORE OVULATION.OVULATION.

THE SURFACE OF THE OVARY, AND AT THE APEX, AN THE SURFACE OF THE OVARY, AND AT THE APEX, AN AVASCULAR SPOT, THE STIGMA, APPEARS.AVASCULAR SPOT, THE STIGMA, APPEARS.

THE HIGH CONCENTRATION OF L.H. INCREASES THE HIGH CONCENTRATION OF L.H. INCREASES COLLAGENASE ACTIVITY.COLLAGENASE ACTIVITY.

PROSTAGLANDIN LEVEL ALSO INCREASE IN RESPO SE TO THE PROSTAGLANDIN LEVEL ALSO INCREASE IN RESPO SE TO THE L.H. SURGE AND CAUSE LOCAL MUSCULAR CONTRACTION IN L.H. SURGE AND CAUSE LOCAL MUSCULAR CONTRACTION IN THE OVARIAN WALL.THE OVARIAN WALL.

THOSE CONTRACTION EXTRUDE THE OOCYTE, WHICH THOSE CONTRACTION EXTRUDE THE OOCYTE, WHICH TOGETHER WITH ITS SURROUNDING GRANULOSA CELLS, TOGETHER WITH ITS SURROUNDING GRANULOSA CELLS, BREAK FREE ( OVULATION ).BREAK FREE ( OVULATION ).

THE CUMULUS OOPHORUS CELLS THEN REARRANGE AROUND THE CUMULUS OOPHORUS CELLS THEN REARRANGE AROUND THE ZONA PELLUCIDA TO FORM THE CORONA RADIATA.THE ZONA PELLUCIDA TO FORM THE CORONA RADIATA.

OVULATIONOVULATION


DURING OVULATION SOME WOMAN DURING OVULATION SOME WOMAN FEEL A SLIGHT PAIN, KNOWN AS FEEL A SLIGHT PAIN, KNOWN AS MIDDLE PAIN.MIDDLE PAIN.

OVULATION IS GENERALLY OVULATION IS GENERALLY ACCOMPANIED BY A RISE IN BASAL ACCOMPANIED BY A RISE IN BASAL TEMPERATURE.TEMPERATURE.

CORPUS LUTEUMCORPUS LUTEUM AFTER OVULASI, GRANULOSA CELLS, TOGETHER AFTER OVULASI, GRANULOSA CELLS, TOGETHER

WITH CELLS FROM THECA INTERNA, ARE WITH CELLS FROM THECA INTERNA, ARE VASCULARIZED BY SURROUNDING VESSELS.VASCULARIZED BY SURROUNDING VESSELS.

UNDER THE INFLUENCE OF L.H. THESE CELLS UNDER THE INFLUENCE OF L.H. THESE CELLS DEVELOP A YELLOWISH PIGMENT AND CHANGE DEVELOP A YELLOWISH PIGMENT AND CHANGE INTO LUTEAN CELLS, WHICH FORM CORPUS INTO LUTEAN CELLS, WHICH FORM CORPUS LUTEUM AND SECRETE THE HORMONE LUTEUM AND SECRETE THE HORMONE PROGESTERON.PROGESTERON.

PROGESTERONE TOGETHER WITH ESTROGENIC PROGESTERONE TOGETHER WITH ESTROGENIC HORMONE, CAUSE THE UTERINE MUCOSA TO ENTER HORMONE, CAUSE THE UTERINE MUCOSA TO ENTER THE PROGESTIONAL OR SECRETORY STAGE IN THE PROGESTIONAL OR SECRETORY STAGE IN PREPARATION FOR IMPLANTATION OF THE PREPARATION FOR IMPLANTATION OF THE EMBRYO.EMBRYO.

OOCYTE TRANSPORTOOCYTE TRANSPORT SHORTLY BEFORE OVULATION FIMBRI AE OF THE SHORTLY BEFORE OVULATION FIMBRI AE OF THE

UTERINE TUBE SWEEP OVER THE SURFACE OF THE UTERINE TUBE SWEEP OVER THE SURFACE OF THE OVARY, AND THE TUBE BEGIN CONTRACT OVARY, AND THE TUBE BEGIN CONTRACT RHYTHMICALLY.RHYTHMICALLY.

IN THE TUBE CUMULUS CELLS WITHDRAW THEIR IN THE TUBE CUMULUS CELLS WITHDRAW THEIR CYTOPLASMIC PROCESSES FROM THE CYTOPLASMIC PROCESSES FROM THE ZONAPELLUCIDA AND LOSE CONTACT WITH THE ZONAPELLUCIDA AND LOSE CONTACT WITH THE OOCYTE.OOCYTE.

THE OOCYTE IN THE TUBE IS PROPELLED BY CILIA THE OOCYTE IN THE TUBE IS PROPELLED BY CILIA WITH THE RATE OF TRANSPORT REGULATED BY WITH THE RATE OF TRANSPORT REGULATED BY THE ENDOCRINE.THE ENDOCRINE.

THE FERTILIZED OOCYTE REACHES THE UTERINE THE FERTILIZED OOCYTE REACHES THE UTERINE LUMEN IN APPROXIMATELY 3 TO 4 DAYS.LUMEN IN APPROXIMATELY 3 TO 4 DAYS.

CORPUS ALBICANSCORPUS ALBICANS

FERTILIZATION DOES NOT OCCUR FERTILIZATION DOES NOT OCCUR - THE CORPUS LUTEUM REACHES MAXI - THE CORPUS LUTEUM REACHES MAXI MUM 9 DAYS AFTER OVULATION.MUM 9 DAYS AFTER OVULATION. - DEGENERATION OF LUTEAL CELLS - DEGENERATION OF LUTEAL CELLS AND FORMS SCAR TISSUE, THE AND FORMS SCAR TISSUE, THE CORPUS ALBICANS.CORPUS ALBICANS. - PROGESTERONE PRODUCTION DECRE - PROGESTERONE PRODUCTION DECRE ASE, PRECIPITATING MENSTRUAL BLEE- ASE, PRECIPITATING MENSTRUAL BLEE- DING.DING.

CORPUS ALBICANSCORPUS ALBICANS OOCYTE IS FERTILIZED OOCYTE IS FERTILIZED - DEGENERATION OF THE CORPUS LUTI - DEGENERATION OF THE CORPUS LUTI UM IS PREVENTED BY HUMAN CHORI- UM IS PREVENTED BY HUMAN CHORI- ONIC GONADOTROPIN (hCG), SECRE- ONIC GONADOTROPIN (hCG), SECRE- TED BY THE SYNCYTIOTROPHOBLAST.TED BY THE SYNCYTIOTROPHOBLAST. - THE CORPUS LUTEUM GROW AND - THE CORPUS LUTEUM GROW AND FORM THE CORPUS LUTEUM OF PREG- FORM THE CORPUS LUTEUM OF PREG- NANCY ( CORP. LUT. GRAVIDITATIS ).NANCY ( CORP. LUT. GRAVIDITATIS ). - LUTEAL CELLS SECRETES PROGESTERON - LUTEAL CELLS SECRETES PROGESTERON UNTIL THE END OF THE 4UNTIL THE END OF THE 4THTH MONTH AND MONTH AND REGRESS SLOWLY.REGRESS SLOWLY. - SECRETION OF PROGESTERONE BY THE - SECRETION OF PROGESTERONE BY THE TROPHOBLAST BECOME ADEQUATE FOR TROPHOBLAST BECOME ADEQUATE FOR MAINTENANCE OF PREGNANCY.MAINTENANCE OF PREGNANCY.

FERTILIZATIONFERTILIZATION

FERTILIZATION, THE PROCESS BY FERTILIZATION, THE PROCESS BY WHICH MALE AND FEMALE GAMETES WHICH MALE AND FEMALE GAMETES FUSE, OCCURS IN THE AMPULLARFUSE, OCCURS IN THE AMPULLARY Y REGION OF THE UTERINE TUBE.REGION OF THE UTERINE TUBE.

THE TRIP OF THE SPERMSTOZOA FROM THE TRIP OF THE SPERMSTOZOA FROM CERVIX TO OVIDUCT REQUIRES 2 TO 7 CERVIX TO OVIDUCT REQUIRES 2 TO 7 HOURS.HOURS.

BEFORE FERTILIZATION BEFORE FERTILIZATION SPERMATOZOA UNDEGO MATURATIONSPERMATOZOA UNDEGO MATURATION

THE PHASE OF FERTILIZATIONTHE PHASE OF FERTILIZATION

PENETRATION OF THE CORONA PENETRATION OF THE CORONA RADIATA.RADIATA.

PENETRATION OF THE PENETRATION OF THE ZONAPELLUCIDA.ZONAPELLUCIDA.

FUSION OF THE OCYTE AND SPERM FUSION OF THE OCYTE AND SPERM CELL MEMBRANES.CELL MEMBRANES.

THE MAIN RESULTTHE MAIN RESULTS OF S OF FERTILIZATIONFERTILIZATION

RESTORATION OF THE DIPLOID RESTORATION OF THE DIPLOID NUMBER OF CHROMOSOMES.NUMBER OF CHROMOSOMES.

DETERMINATION OF THE SEX.DETERMINATION OF THE SEX. INITIATION OF CLEAVAGEINITIATION OF CLEAVAGE


CONTRACEPTIVE METHODS.CONTRACEPTIVE METHODS. INFERTILITYINFERTILITY

CLEAVAGECLEAVAGE

MORULAMORULA

THE INNER CELL MASSTHE INNER CELL MASS

gives rise to tissues of the embryo proper.gives rise to tissues of the embryo proper. THE OUTER CELL MASSTHE OUTER CELL MASS

forms the trophoblast, which later contributes forms the trophoblast, which later contributes

to the placenta.to the placenta.

BLASTOCYST FORMATIONBLASTOCYST FORMATION

THE FIRST WEEK OF HUMAN THE FIRST WEEK OF HUMAN DEVELOPMENTDEVELOPMENT

SECOND WEEK OF SECOND WEEK OF DEVELOPMENTDEVELOPMENT

DAY 8DAY 8

THE TROPHOBLAST HAS DIFFERENTIATED IN THE TROPHOBLAST HAS DIFFERENTIATED IN TO :TO :

- THE CYTOTROPHOBLAST.- THE CYTOTROPHOBLAST.

- THE SYNCYTIOTROPHOBLAST.- THE SYNCYTIOTROPHOBLAST. THE EMBRYOBLAST DIFFERENTIATE IN TO :THE EMBRYOBLAST DIFFERENTIATE IN TO :

- THE HYPOBLAST LAYE- THE HYPOBLAST LAYE

- THE EPIBLAST LAYER.- THE EPIBLAST LAYER. THE AMNIOTIC CAVITY APPEARS WITHIN THE AMNIOTIC CAVITY APPEARS WITHIN

THE EPIBLAST.THE EPIBLAST.

DAY 9DAY 9

DAY 9DAY 9

VACUOLES APPEAR IN THE VACUOLES APPEAR IN THE SYNCYTIUM ---- LACUNAR STAGE.SYNCYTIUM ---- LACUNAR STAGE.

THE EXOCOELOMIC MEMBRANE IS THE EXOCOELOMIC MEMBRANE IS FORMED FROM THE HYPOBLAST.FORMED FROM THE HYPOBLAST.

THE EXOCOELOMIC MEMBRANE WITH THE EXOCOELOMIC MEMBRANE WITH HYPOBLAST, FORM LINING OF THE HYPOBLAST, FORM LINING OF THE EXOCOELOMIC CAVITY ( PRIMITIVE EXOCOELOMIC CAVITY ( PRIMITIVE YOLK SAC )YOLK SAC )

DAY 11 AND 12DAY 11 AND 12

DAY 11 AND 12DAY 11 AND 12 LACUNAR SPACES IN THE SYNCYTIUM FORM LACUNAR SPACES IN THE SYNCYTIUM FORM

AN INTERCOMMUNICATING NET WORK.AN INTERCOMMUNICATING NET WORK. CELLS OF THE SYNCYTIOTROPHOBLAS CELLS OF THE SYNCYTIOTROPHOBLAS

PENETRATE THE STROMA AND ERODE THE PENETRATE THE STROMA AND ERODE THE MATERNAL CAPILLARIES – CAPI- LLARIES MATERNAL CAPILLARIES – CAPI- LLARIES ARE CONGESTED AND DILATATED ARE ARE CONGESTED AND DILATATED ARE KNOWN SINUSOID.KNOWN SINUSOID.

THE SYNCYTIAL LACUNNAE BECOME THE SYNCYTIAL LACUNNAE BECOME CONTINUOUS WIYH THE SINUSOID AND CONTINUOUS WIYH THE SINUSOID AND MATERNAL BLOOD ENTER THE LACUNAR MATERNAL BLOOD ENTER THE LACUNAR SYSTEM – THE UTEROPLACENTAL SYSTEM – THE UTEROPLACENTAL CIRCULATION.CIRCULATION.

DAY 11 AND 12DAY 11 AND 12 THE EXTRAEMBRYONIC MESODERM IS THE EXTRAEMBRYONIC MESODERM IS

FORMED BETWEEN THE INNER SURFA- CE OF FORMED BETWEEN THE INNER SURFA- CE OF THE CYTOTROPHOBLAST AND THE OUTER THE CYTOTROPHOBLAST AND THE OUTER SURFACE OF THE EXOCOE- LOMIC CAVITY.SURFACE OF THE EXOCOE- LOMIC CAVITY.

THE EXTRA EMBRYONIC COELOM DEVELOP THE EXTRA EMBRYONIC COELOM DEVELOP IN THE EXTRAEMBRYONIC MESODERM.IN THE EXTRAEMBRYONIC MESODERM.

THE EXTRAEMBRYONIC MESODERM ; THE EXTRAEMBRYONIC MESODERM ; - the extraembryonic somtopleuric mesoderm.- the extraembryonic somtopleuric mesoderm. - the extraembryonic splanchnopleuric mesoderm.- the extraembryonic splanchnopleuric mesoderm. CELLS OF THE ENDOMETRIUM UNDERGO CELLS OF THE ENDOMETRIUM UNDERGO

DECIDUA REACTION.DECIDUA REACTION.

DAY 13DAY 13

DAY 13DAY 13 NEAR THE 28NEAR THE 28THTH DAY OF THE MENSTRUAL DAY OF THE MENSTRUAL

CYCLE, BLEEDING OCCUR AT THE CYCLE, BLEEDING OCCUR AT THE IMPLANTATION SITE AS ARESULT OF IMPLANTATION SITE AS ARESULT OF INCREASED BLOOD FLOW IN TO LACUNAR INCREASED BLOOD FLOW IN TO LACUNAR SPACE.SPACE.

THE PRIMARY VILLI IS FORMED, CONSIST OF THE PRIMARY VILLI IS FORMED, CONSIST OF THE CYTOTROPHOBLAST. THE CYTOTROPHOBLAST. THESYNCYTIOTROPHOBLAST.THESYNCYTIOTROPHOBLAST.

THE SECONDARY YOLK SAC IS FORMED THE SECONDARY YOLK SAC IS FORMED FROM THE HYPOBLAST, WICH MIGRATE FROM THE HYPOBLAST, WICH MIGRATE ALONG THE INSIDE OF THE EXOCOELOMIC ALONG THE INSIDE OF THE EXOCOELOMIC MEMBRANE.MEMBRANE.

DAY 13DAY 13 THE EXOCOELOMIC CAVITY ARE PINCHED THE EXOCOELOMIC CAVITY ARE PINCHED

OFF – EXOCOELOMIC CYST ARE FORMED.OFF – EXOCOELOMIC CYST ARE FORMED. THE EXTRAEMBRYONIC COELOM EXPAND THE EXTRAEMBRYONIC COELOM EXPAND

AND FORM THE CHORIONIC CAVITY.AND FORM THE CHORIONIC CAVITY. THE EXTRAEMBRYONIC MESODERM LINING THE EXTRAEMBRYONIC MESODERM LINING

THE INSIDE OF THE CYTOTRO- PHOBLAS IS THE INSIDE OF THE CYTOTRO- PHOBLAS IS KNOWN AS THE CHORIONIC PLATE.KNOWN AS THE CHORIONIC PLATE.

THE EXTRAEMBRYONIC MESODERM THE EXTRAEMBRYONIC MESODERM TRAVERSE THE CHORIONIC CAVITY IS IN TRAVERSE THE CHORIONIC CAVITY IS IN THE CONNECTING STALK.THE CONNECTING STALK.

WITH THE DEVELOPMENT OF THE BLOOD WITH THE DEVELOPMENT OF THE BLOOD VESSELS, THE STALK BECOME UMBILICAL VESSELS, THE STALK BECOME UMBILICAL CORD./CORD./

CLINICAL CORRELATESCLINICAL CORRELATES EARLY PREGNANCY FACTOR IN THE EARLY PREGNANCY FACTOR IN THE

MATERNAL SERUM CAN BE DETECTED 24 TO MATERNAL SERUM CAN BE DETECTED 24 TO 48 HOURS AFTER FERTILIZATION.48 HOURS AFTER FERTILIZATION.

BY THE END OF 2BY THE END OF 2NDND WEEK hCG FROM WEEK hCG FROM SYNCYTIOTROPHOBLASTSYNCYTIOTROPHOBLAST ARE SUFFICIENT ARE SUFFICIENT TO BE DETECTED.TO BE DETECTED.

50% OF IMPLANTING EMBRYO S GENOME IS 50% OF IMPLANTING EMBRYO S GENOME IS DERIVED FROM THE FATHER, IT IS A DERIVED FROM THE FATHER, IT IS A FOREIGN BODY,--- IF THE MOTHER HAS FOREIGN BODY,--- IF THE MOTHER HAS AUTOIMMUNE DISEASE ANTIBODY GENERA- AUTOIMMUNE DISEASE ANTIBODY GENERA- TED BY THE DISEASE MAY ATTACK THE TED BY THE DISEASE MAY ATTACK THE CONCEPTUS AND REJECT IT.CONCEPTUS AND REJECT IT.


ABNORMAL IMPLANTATION SITEABNORMAL IMPLANTATION SITE - WITHIN THE UTERUS- WITHIN THE UTERUS - PLACENTA PREVIA- PLACENTA PREVIA - OUT SIDE THE UTERUS- OUT SIDE THE UTERUS - ECTOPIC PREGNANCY- ECTOPIC PREGNANCY the embryo die about 2the embryo die about 2ndnd month of month of gestation.gestation. ABNORMAL BLASTOCYSTABNORMAL BLASTOCYST - HYDATIDIFORM MOLE.- HYDATIDIFORM MOLE.

THIRD WEEK OF THIRD WEEK OF DEVELOPMENTDEVELOPMENT

TRILAMINAR GERM DISC.TRILAMINAR GERM DISC. THE BEGINNING OF THE EMBRYONIC THE BEGINNING OF THE EMBRYONIC

PERIOD, THAT TERMINATES AT THE END OF PERIOD, THAT TERMINATES AT THE END OF THE EIGHTH WEEK.THE EIGHTH WEEK.

GASTRULATION, INCLUDE PROCES FOR GASTRULATION, INCLUDE PROCES FOR MATION OF THE PRIMITIVE STREAK, MATION OF THE PRIMITIVE STREAK, NOTOCHORD AND GERM LATERS ( THE NOTOCHORD AND GERM LATERS ( THE BILAMINAR EMBRYONIC DISC IS BILAMINAR EMBRYONIC DISC IS CONVERTED INTO TRILAMINAR EMBRYONIC CONVERTED INTO TRILAMINAR EMBRYONIC DISC.DISC.

THE PRIMITIVE STREAKTHE PRIMITIVE STREAK

IS FORMED IN THE BEGINNING OF THE THIRD IS FORMED IN THE BEGINNING OF THE THIRD WEEK.WEEK.

RESULT FROM THE PROLIFERATION AND RESULT FROM THE PROLIFERATION AND MIGRATION OF CELLS OF THE EPIBLAST TO MIGRATION OF CELLS OF THE EPIBLAST TO THE MEDIAN PLANE OF THE EMBRYONIC THE MEDIAN PLANE OF THE EMBRYONIC DISCDISC . .

AT THE END OF THE 4AT THE END OF THE 4THTH WEEK THE PRIMITIVE WEEK THE PRIMITIVE STREAK DEMINISHED AND DISAPPEAR.STREAK DEMINISHED AND DISAPPEAR.

GERM DISC AT THE END OF GERM DISC AT THE END OF THE 2THE 2NDND WEEK OF WEEK OF DEVELOPMENTDEVELOPMENT

GASTRULATIONGASTRULATION

CELLS OF THE EPIBLAST THROUGH CELLS OF THE EPIBLAST THROUGH THE PROCESS OF GASTRULATION GIVE THE PROCESS OF GASTRULATION GIVE RISE TO :RISE TO :

- INTRA EMBRYONIC MESODRM.- INTRA EMBRYONIC MESODRM.

- “ ENDODERM.- “ ENDODERM.

- “ ECTODERM.- “ ECTODERM.

GERM DISC FROM 16 DAYGERM DISC FROM 16 DAY

CROSS SECTION OF THE CROSS SECTION OF THE STREAK AT 15 DAYSSTREAK AT 15 DAYS

DEVELOPMENT OF THE DEVELOPMENT OF THE NOTOCHORDAL PROCESSNOTOCHORDAL PROCESS

DEVELOPMENT OF THE DEVELOPMENT OF THE NOTOCHORDNOTOCHORD

FATE OF THE NOTOCHORDFATE OF THE NOTOCHORD THE NOTOCHORD IS THE STRUCTURE AROUND THE NOTOCHORD IS THE STRUCTURE AROUND

WHICH THE VERTEBRAL COLUMN FORM.WHICH THE VERTEBRAL COLUMN FORM. IT EXTENDS FROM THE OROPHARYNGE AL IT EXTENDS FROM THE OROPHARYNGE AL

MEMBRANE TO THE PRIMITIVE NODE.MEMBRANE TO THE PRIMITIVE NODE. THE NOTOCHORD DEGENERATES AND DISAPPEARSTHE NOTOCHORD DEGENERATES AND DISAPPEARS

AS THE VERTEBRAL BODY FORM, BUT IT PERSISTS AS THE VERTEBRAL BODY FORM, BUT IT PERSISTS AS THE NUCLEUS PULPOSUS.AS THE NUCLEUS PULPOSUS.

THE DEVELOPING NOTOCHORD INDUCES THE THE DEVELOPING NOTOCHORD INDUCES THE OVERLYING ECTODERM TO FORM THE NEURAL OVERLYING ECTODERM TO FORM THE NEURAL PLATE, THE PRIMORDIUM OF THE CENTRAL PLATE, THE PRIMORDIUM OF THE CENTRAL NERVOUS SYSTEM.NERVOUS SYSTEM.

WHEN DEVELOPMENT OF THE NOTOCHORD IS WHEN DEVELOPMENT OF THE NOTOCHORD IS COMPLETE, THE NEURENTERIC CANAL NORMALLY COMPLETE, THE NEURENTERIC CANAL NORMALLY OBLITERATES.OBLITERATES.

Cl. correlatesCl. correlates

CONJOINED TWINCONJOINED TWINIf the gene GoosecoidIf the gene Goosecoidis over expressed in is over expressed in frog embryo, the result frog embryo, the result is a two-headed tad pole.is a two-headed tad pole.Perhap, over expression Perhap, over expression of this gene explain the of this gene explain the origin of this type of origin of this type of conjoined twinconjoined twin


SIRENOMELIASIRENOMELIA

Los of mesoderm Los of mesoderm

in the lumbosacralin the lumbosacral

region has resulted region has resulted

in fusion of the in fusion of the

limb buds and limb buds and

other defectsother defects


SACROCOCCYGEAL SACROCOCCYGEAL TERATOMA resultingTERATOMA resultingfrom remnants of the from remnants of the primitive streak. These primitive streak. These tumors may become ma tumors may become ma lignant and are most lignant and are most commonn in female commonn in female fetus.fetus.

THE ALLANTOISTHE ALLANTOIS APPEAR ON ABOUT DAY 16 AS DIVERTICULUM APPEAR ON ABOUT DAY 16 AS DIVERTICULUM

FROM THE CAUDAL WALL OF THE YOLK SAC, AND FROM THE CAUDAL WALL OF THE YOLK SAC, AND EXTEND INTO THE CONNECTING STALKEXTEND INTO THE CONNECTING STALK..

INVOLVED WITH EARLY BLOOD FORMATION.INVOLVED WITH EARLY BLOOD FORMATION. ASSOCIATED WITH DEVELOPMENT OF THE URINARY ASSOCIATED WITH DEVELOPMENT OF THE URINARY

BLADDER.BLADDER. AS BLADER ENLARGE, THE ALLANTOIS BECOME AS BLADER ENLARGE, THE ALLANTOIS BECOME

THE URACHUS.THE URACHUS. IN ADULT IS REPRESENTED AS THE MEDIAN IN ADULT IS REPRESENTED AS THE MEDIAN

UMBILICAL LIGAMENT.UMBILICAL LIGAMENT. THE BLOOD VESSELS OF THE ALLANTOIS BECOME THE BLOOD VESSELS OF THE ALLANTOIS BECOME

THE UMBILICAL ARTERIES AND VEINS.THE UMBILICAL ARTERIES AND VEINS.

NEURULATIONNEURULATION

THE PROCESSES INVOLVED IN THE THE PROCESSES INVOLVED IN THE FORMATION OF THE NEURAL PLATE AND FORMATION OF THE NEURAL PLATE AND NEURAL FOLD AND THE CLOSURE OF THESE NEURAL FOLD AND THE CLOSURE OF THESE FOLD TO FORM THE NEURAL TUBE.FOLD TO FORM THE NEURAL TUBE.

BEGIN AT DAY 17 --- THE END OF THE 4BEGIN AT DAY 17 --- THE END OF THE 4THTH WEEK, WHEN CLOSURE OF THE CAUDAL WEEK, WHEN CLOSURE OF THE CAUDAL NEUROPORE.NEUROPORE.

THE EMBRYO MAY BE REFERED TO AS A THE EMBRYO MAY BE REFERED TO AS A NEURULA.NEURULA.

NEURAL CRESTNEURAL CREST

THE SENSORY GANGLIA OF THE THE SENSORY GANGLIA OF THE SPINAL AND CRANIAL V, VII, IX, AND X.SPINAL AND CRANIAL V, VII, IX, AND X.

THE SHEATH OF NERVES.THE SHEATH OF NERVES. MENINGEAL COVERING.MENINGEAL COVERING. MEDULLA SUPRARENALMEDULLA SUPRARENAL

DEVELOPMENT OF SOMITESDEVELOPMENT OF SOMITES

THE SOMITES FIRST APPEAR AT THE END OF THE SOMITES FIRST APPEAR AT THE END OF THE 3THE 3RDRD WEEK, IN FUTURE OCCIPITAL WEEK, IN FUTURE OCCIPITAL REGION OF THE EMBRYO.REGION OF THE EMBRYO.

APPEAR CRANIOCAUDALLY AND GIVE RISE APPEAR CRANIOCAUDALLY AND GIVE RISE TO MOST OF THE AXIAL SKELETON AND TO MOST OF THE AXIAL SKELETON AND ASSOCIATED MUSCULAR, AS WELL AS TO ASSOCIATED MUSCULAR, AS WELL AS TO THE ADJACENT DERMIS OF THE SKIN.THE ADJACENT DERMIS OF THE SKIN.

BY THE END OF THE 5BY THE END OF THE 5THTH WEEK, 42 – 44 PAIRS WEEK, 42 – 44 PAIRS ARE PRESENT.ARE PRESENT.

DEVELOPMENT OF THE DEVELOPMENT OF THE INTRAEMBRYONIC COELOMINTRAEMBRYONIC COELOM

DURING THE SECOND MONTH THE DURING THE SECOND MONTH THE INTRAEMBRYONIC COELOM IS INTRAEMBRYONIC COELOM IS DIVIDED INTO : DIVIDED INTO :

1. THE PERICARDIAL CAVITY.1. THE PERICARDIAL CAVITY.

2. THE PLEURAL CAVITIES.2. THE PLEURAL CAVITIES.

3. THE PERITONEAL CAVITY.3. THE PERITONEAL CAVITY.

EARLY DEVELOPMENT OF THE EARLY DEVELOPMENT OF THE CARDIOVASCULAR SYSTEMCARDIOVASCULAR SYSTEM

AT THE BEGINNING OF THE 3AT THE BEGINNING OF THE 3RDRD WEEK WEEK ANGIOGENESIS BEGIN IN :ANGIOGENESIS BEGIN IN :

- Extra embryonic mesoderm covering yolk s- Extra embryonic mesoderm covering yolk s - Connecting stalk.- Connecting stalk. - Chorion.- Chorion. AT THE END OF 2AT THE END OF 2NDND WEEK EMBRYONIC WEEK EMBRYONIC

NUTRITION IS OBTAINED FROM THE NUTRITION IS OBTAINED FROM THE MATERNAL BLOD BY DIFFUSION THROUGHMATERNAL BLOD BY DIFFUSION THROUGH

- Extra embryonic coelom.- Extra embryonic coelom. - Yolk sac.- Yolk sac. DURING THE 3DURING THE 3RDRD WEEK A PRIMITIVE WEEK A PRIMITIVE

PLACENTAL CIRCULATION DEVELOP.PLACENTAL CIRCULATION DEVELOP.

ANGIOGENESIS AND ANGIOGENESIS AND HEMATOGENESISHEMATOGENESIS

PRIMITIVE BLOOD CELLS AND PRIMITIVE BLOOD CELLS AND PLASMPLASM

BLOOD DEVELOP FROM BLOOD DEVELOP FROM

- Endothelial cells.- Endothelial cells. VESSELS DEVELOP ON VESSELS DEVELOP ON

- Yolk sac- Yolk sac

- Allantois.- Allantois. BEGIN AT THE END OF THE 3BEGIN AT THE END OF THE 3RDRD WEEK WEEK

UNTIL THE END OF THE 4UNTIL THE END OF THE 4THTH WEEK WEEK

THE PRIMITIVE THE PRIMITIVE CARDIOVASCULAR SYSTEMCARDIOVASCULAR SYSTEM

THE HEART AND GREAT VESSELS FORM THE HEART AND GREAT VESSELS FORM FROM MESENCHYMAL CELLS IN THE FROM MESENCHYMAL CELLS IN THE CARDIOGRNIC AREA.CARDIOGRNIC AREA.

ENDOTHELIAL HEART TUBES DEVELOP ENDOTHELIAL HEART TUBES DEVELOP BEFORE THE END OF THE 3BEFORE THE END OF THE 3RDRD WEEK AND WEEK AND BEGIN TO FUSE INTO A PRIMITIVE HEART BEGIN TO FUSE INTO A PRIMITIVE HEART TUBE.TUBE.

HEART TUBE IS JOINED TO BLOOD VESSELS HEART TUBE IS JOINED TO BLOOD VESSELS IN THE EMBRYO, CONNECTING STALK, IN THE EMBRYO, CONNECTING STALK, CHORION AND YOLK SAC TO FORM A CHORION AND YOLK SAC TO FORM A PRIMITIVE CARDIOVACULAR SYSTEMPRIMITIVE CARDIOVACULAR SYSTEM

THE PRIMITIVE THE PRIMITIVE CARDIOVASCULAR SYSTEMCARDIOVASCULAR SYSTEM

BY THE END OF THE 3BY THE END OF THE 3RDRD WEEK THE WEEK THE BLOOD IS CIRCULATING, AND THE BLOOD IS CIRCULATING, AND THE HEART BEGIN TO BEAT ON THE HEART BEGIN TO BEAT ON THE TWENTY-FIRST OR TWENTY-SECOND TWENTY-FIRST OR TWENTY-SECOND DAY ( ABOUT 5 WEEK AFTER L.N.M.P.)DAY ( ABOUT 5 WEEK AFTER L.N.M.P.)

THE EMBRYONIC HEART BEAT CAN BE THE EMBRYONIC HEART BEAT CAN BE DETECTED ULTRASONOGRAPHYCALLY DETECTED ULTRASONOGRAPHYCALLY WITH A DOPPLER DURING THE 5WITH A DOPPLER DURING THE 5THTH WEEK ( 7 WEEK AFTER L.N.M.P.)WEEK ( 7 WEEK AFTER L.N.M.P.)

PRIMITIVE CARDIOVASCULAR PRIMITIVE CARDIOVASCULAR SYSTEMSYSTEM

DEVELOPMENT OF CHORIONIC DEVELOPMENT OF CHORIONIC VILLIVILLI

THE PRIMARY CHORIONIC VILLI APPEAR AT THE PRIMARY CHORIONIC VILLI APPEAR AT THE END OF THE 2THE END OF THE 2NDND WEEK. WEEK.

SECONDARY CHORIONIC VILLI APPEAR AT SECONDARY CHORIONIC VILLI APPEAR AT EARLY IN THE 3EARLY IN THE 3RDRD WEEK. WEEK.

TERTIARY CHORIONIC VILLI ( STEM VILLI ), TERTIARY CHORIONIC VILLI ( STEM VILLI ), BLOOD VESSELS HAVE DEVELOPED IN THE BLOOD VESSELS HAVE DEVELOPED IN THE VILLI.VILLI.

THE VESSELS IN THESE STEM VILLI SOON THE VESSELS IN THESE STEM VILLI SOON BECOME CONNECTED WITH THE BECOME CONNECTED WITH THE EMBRYONIC HEART.EMBRYONIC HEART.

DEVELOPMENT OF CHORIONIC DEVELOPMENT OF CHORIONIC VILLIVILLI

BY THE END OF THE 3BY THE END OF THE 3RDRD WEEK EMBRYONIC BLOOD WEEK EMBRYONIC BLOOD BEGINS TO FLOW THROUGH THE CAPILLARY IN THE BEGINS TO FLOW THROUGH THE CAPILLARY IN THE CHORIONIC VILLI.CHORIONIC VILLI.

OXYGEN AND NUTRIENTS IN THE MATERNAL OXYGEN AND NUTRIENTS IN THE MATERNAL BLOOD, IN THE INTERVILLOUS SPACE DIFFUSE BLOOD, IN THE INTERVILLOUS SPACE DIFFUSE THROUGH THE WALL OF THE VILLI ( PLACENTAL THROUGH THE WALL OF THE VILLI ( PLACENTAL MEMBRANE ) AND ENTER THE EMBRYO”S BLOOD.MEMBRANE ) AND ENTER THE EMBRYO”S BLOOD.

CYTOTROPHOBLAST CELLS OF THE CHORIONIC CYTOTROPHOBLAST CELLS OF THE CHORIONIC VILLI PROLIFERATE AND EXTEND THROUGH THE VILLI PROLIFERATE AND EXTEND THROUGH THE SYNCYTIOTROPHO- BLASTIC LAYER TO FORM A SYNCYTIOTROPHO- BLASTIC LAYER TO FORM A SYNCYTIOTROPHOBLASTIC SHELL, WHICH SYNCYTIOTROPHOBLASTIC SHELL, WHICH ATTACHESATTACHES THE CHORIONIC SAC TO THE THE CHORIONIC SAC TO THE ENDOMETRIUMENDOMETRIUM

ABNORMAL GROWTH OF THE ABNORMAL GROWTH OF THE TROPHOBLASTTROPHOBLAST

EMBRYO DIE ---- CHORIONIC VILLI EMBRYO DIE ---- CHORIONIC VILLI FORM CYSTIC SWELLING ---- FORM CYSTIC SWELLING ---- HYDATIDIFORM MOLE.HYDATIDIFORM MOLE.

EXCESSIVE AMOUNT OF hCG AREEXCESSIVE AMOUNT OF hCG ARE PRODUCED.PRODUCED.

ABOUT TWO PER CENT OF THESE MOLE ABOUT TWO PER CENT OF THESE MOLE DEVELOP INTO CHORIOCARCINOMA.DEVELOP INTO CHORIOCARCINOMA.

Dr.amin Embryology

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