CONCEPTION,NIDATION AND CONCEPTION,NIDATION AND PLACENTAL DEVELOP0MENTPLACENTAL DEVELOP0MENT

CONCEPTIONCONCEPTION

FERTILIZATION OR UNION OF THE FERTILIZATION OR UNION OF THE MALE AND FEMALE GAMETES(SPERM MALE AND FEMALE GAMETES(SPERM AND OVUM)AND OVUM)

SAME AS PREGNANCYSAME AS PREGNANCY

NIDATIONNIDATION

IMPLANTATION OR EMBEDDING OF IMPLANTATION OR EMBEDDING OF THE PRODUCT OF FERTILIZATION OR THE PRODUCT OF FERTILIZATION OR ZYGOTE INTO THE UTERINE CAVITYZYGOTE INTO THE UTERINE CAVITY

A NIDUS IS A CAVITY IN WHICH A NIDUS IS A CAVITY IN WHICH PLANT SPORES DEVELOPPLANT SPORES DEVELOP

NIDATIONNIDATION

SPERMATOGENESISSPERMATOGENESIS

STAGES OF DEVELOPMENT OF THE STAGES OF DEVELOPMENT OF THE SPERM OCCURING IN THE TESTIS.SPERM OCCURING IN THE TESTIS.

THE PROCESS STARTS AT PUBERTYTHE PROCESS STARTS AT PUBERTY

IT TAKES ABOUT 72 DAYS FROM IT TAKES ABOUT 72 DAYS FROM SPERMATOGONIUM TO MATURE SPERMATOGONIUM TO MATURE SPERM.SPERM.

OOGENESISOOGENESIS

STARTS DURING INTRAUTERINE LIFE.STARTS DURING INTRAUTERINE LIFE.

ALL THE PRIMARY OOCYTES ARE ALL THE PRIMARY OOCYTES ARE FORMED BEFORE BIRTH.FORMED BEFORE BIRTH.

THE PRIMARY OOCYTE BEGINS THE THE PRIMARY OOCYTE BEGINS THE FIRST MEIOTIC DIVISION JUST FIRST MEIOTIC DIVISION JUST BEFORE BIRTH.BEFORE BIRTH.

COMPLETION OF THE PROPHASE COMPLETION OF THE PROPHASE OCCURS JUST BEFORE PUBERTY.OCCURS JUST BEFORE PUBERTY.

OOGENESISOOGENESIS

BEFORE PUBERTY, THE PRIMARY BEFORE PUBERTY, THE PRIMARY OOCYTE INCREASES IN SIZE AND OOCYTE INCREASES IN SIZE AND ZONA PELLUCIDA FORMS AROUND IT.ZONA PELLUCIDA FORMS AROUND IT.

BEFORE OVULATION, PRIMARY BEFORE OVULATION, PRIMARY OOCYTE COMPLETES FIRST MEIOTIC OOCYTE COMPLETES FIRST MEIOTIC DIVISION ,RESULTING IN SECONDARY DIVISION ,RESULTING IN SECONDARY OOCYTE AND FIRST POLAR BODYOOCYTE AND FIRST POLAR BODY

OOGENESISOOGENESISWITH THE ONSET OF OVULATION,THE WITH THE ONSET OF OVULATION,THE NUCLEUS OF THE SECONDARY OOCYTE NUCLEUS OF THE SECONDARY OOCYTE ENTERS THE SECOND MEIOTIC DIVISION ENTERS THE SECOND MEIOTIC DIVISION AND PROCEEDS TO METAPHASE UNTIL AND PROCEEDS TO METAPHASE UNTIL FERTILIZATION.FERTILIZATION.THE SECONDARY OOCYTE RELEASED AT THE SECONDARY OOCYTE RELEASED AT OVULATION IS CALLED OVUM.OVULATION IS CALLED OVUM.IT IS SURROUNDED BY ZONA PELLUCIDA IT IS SURROUNDED BY ZONA PELLUCIDA AND CORONA RADIATA.AND CORONA RADIATA.SECOND POLAR BODY IS FORMED AFTER SECOND POLAR BODY IS FORMED AFTER FERTILIZATION AND IS EXPELLED.FERTILIZATION AND IS EXPELLED.

SPERMATOGENSIS AND SPERMATOGENSIS AND OOGENESISOOGENESIS

STRUCTURE OF SPERMSTRUCTURE OF SPERM

STRUCTURE OF SECONDARY STRUCTURE OF SECONDARY OOCYTEOOCYTE

1.OVUM1.OVUM

2. ZONA PELLUCIDA2. ZONA PELLUCIDA

3. CORONA RADIATA3. CORONA RADIATA

COMPOSITION OF SEMENCOMPOSITION OF SEMEN

FROM THE FOLLOWING ORGANSFROM THE FOLLOWING ORGANS

1.TESTIS1.TESTIS

2. SEMINAL VESICLE2. SEMINAL VESICLE

3.PROSTATE3.PROSTATE

4.URETHRAL GLANDS4.URETHRAL GLANDS

TRANSPORT OF SEMENTRANSPORT OF SEMENALKALINE SEMEN DEPOSITED IN THE ALKALINE SEMEN DEPOSITED IN THE VAGINA AFTER SEXUAL INTERCOURSE VAGINA AFTER SEXUAL INTERCOURSE COAGULATES THEN LIQUIFIES.COAGULATES THEN LIQUIFIES.AFTER 30MINS IN THE VAGINA WHICH IS AFTER 30MINS IN THE VAGINA WHICH IS ACID THEY LOOSE MOTILITY AND UNABLE ACID THEY LOOSE MOTILITY AND UNABLE TO PENETRATE THE CERVICAL MUCUS AND TO PENETRATE THE CERVICAL MUCUS AND DIE.DIE.SPERMS CAN SURVIVE FOR 1-3 DAYS IN SPERMS CAN SURVIVE FOR 1-3 DAYS IN THE CERVICAL MUCUS AND FURTHER 2 THE CERVICAL MUCUS AND FURTHER 2 DAYS IN THE FALLOPIAN TUBEDAYS IN THE FALLOPIAN TUBE

TRANSPORT OF SPERMTRANSPORT OF SPERM

BY PERISTALSIS ASSISTED BY TUBAL BY PERISTALSIS ASSISTED BY TUBAL FLUID ,CILIA AND MUSCULAR FLUID ,CILIA AND MUSCULAR CONTRATION.CONTRATION.

DURING THE JOURNEY TO THE TUBE DURING THE JOURNEY TO THE TUBE THE SPERMS GAIN ABILITY TO THE SPERMS GAIN ABILITY TO FERTILIZE THE OVUM BY PROCESSES FERTILIZE THE OVUM BY PROCESSES OF CAPACITATION AND ACROSOMAL OF CAPACITATION AND ACROSOMAL REACTIONREACTION

CAPACITATION AND CAPACITATION AND ACROSOMAL REACTIONACROSOMAL REACTION

CAPACITATION-THE PROCESS WHICH CAPACITATION-THE PROCESS WHICH REMOVES THE SPERM MEMBRANES.REMOVES THE SPERM MEMBRANES.

ACROSOMAL REACTION IS THE PROCESS ACROSOMAL REACTION IS THE PROCESS WHEREBY THE CAPACITATED SPERM WHEREBY THE CAPACITATED SPERM LOOSES ITS ACROSOMAL MEMBRANES LOOSES ITS ACROSOMAL MEMBRANES RELEASING THE ENZYMES WHICH HELPS RELEASING THE ENZYMES WHICH HELPS THE PENETRATION OF THE ZONA THE PENETRATION OF THE ZONA PELLUCIDAPELLUCIDA

OVUMOVUMAT OVULATION, THE FIMBRIAL END OF THE AT OVULATION, THE FIMBRIAL END OF THE TUBE COMES VERY CLOSE TO THE OVARY.TUBE COMES VERY CLOSE TO THE OVARY.

WHEN THE OVUM IS RELEASED, IT IS WHEN THE OVUM IS RELEASED, IT IS CARRIED BY PERITONEAL FLUID INTO THE CARRIED BY PERITONEAL FLUID INTO THE TUBE BY CILIARY ACTION OF EPITHELIAL TUBE BY CILIARY ACTION OF EPITHELIAL CELLS AND MUSCULAR CONTRACTIONS.CELLS AND MUSCULAR CONTRACTIONS.

THE FERTILE LIFE OF THE OVUM IS ABOUT THE FERTILE LIFE OF THE OVUM IS ABOUT 24 HRS24 HRS

FERTILIZATIONFERTILIZATION

NORMALLY OCCURS AT THE NORMALLY OCCURS AT THE AMPULLA OF THE FALLOPIAN TUBEAMPULLA OF THE FALLOPIAN TUBE

INVOLVES FUSION OF OVUM AND INVOLVES FUSION OF OVUM AND SPERM.SPERM.

ONLY ONE SPERM FERTILIZES THE ONLY ONE SPERM FERTILIZES THE OVUMOVUM

SPERM IS ATTRACTED TO OVUM BY SPERM IS ATTRACTED TO OVUM BY CHEMOTAXIS.CHEMOTAXIS.

FERTILIZATIONFERTILIZATIONMANY SPERMS ENTER THE ZONA MANY SPERMS ENTER THE ZONA PELLUCIDA BUT AS SOON AS ONE PELLUCIDA BUT AS SOON AS ONE SPERM GETS INTO THE CYTOPLASM, SPERM GETS INTO THE CYTOPLASM, THE OVUM SEPERATES FROM THE THE OVUM SEPERATES FROM THE ZONA.ZONA.THE HEAD OF THE SPERM WHICH IS THE HEAD OF THE SPERM WHICH IS THE NUCLEUS FUSES WITH THE THE NUCLEUS FUSES WITH THE NUCLEUS OF THE OVUM TO FORM NUCLEUS OF THE OVUM TO FORM THE ZYGOTE.THE ZYGOTE.

FERTILIZATIONFERTILIZATION

THE ZYGOTE IS CARRIED DOWN THE THE ZYGOTE IS CARRIED DOWN THE TUBE BY PERISTALSIS AND CILIARY TUBE BY PERISTALSIS AND CILIARY ACTION AND REACHES THE UTERINE ACTION AND REACHES THE UTERINE CAVITY ABOUT 5-6 DAYS AFTER CAVITY ABOUT 5-6 DAYS AFTER OVULATION.OVULATION.

FERTILIZATIONFERTILIZATION

IMPLANTATIONIMPLANTATION

EARLY DEVELOPMENT AND EARLY DEVELOPMENT AND EMBEDDING OF BLASTOCYSTEMBEDDING OF BLASTOCYST

ZYGOTE UNDERGOES MITOTIC ZYGOTE UNDERGOES MITOTIC DIVISION FORMING TWO DAUGHTER DIVISION FORMING TWO DAUGHTER CELLS CALLED BLASTOMERES CELLS CALLED BLASTOMERES WITHIN 30 HRS AFTER WITHIN 30 HRS AFTER FERTILIZATIONFERTILIZATION

LATER DIVISION OCCURS ABOUT LATER DIVISION OCCURS ABOUT EVERY 24HRS UNTIL A MORULA EVERY 24HRS UNTIL A MORULA FORMS WHICH IS ABOUT 16 FORMS WHICH IS ABOUT 16 BLASTOMERES.BLASTOMERES.

CAVITY APPEARS IN THE MORULA AND IS CAVITY APPEARS IN THE MORULA AND IS NOW CALLED BLASTOCYST.NOW CALLED BLASTOCYST.

THE BLASTOCYST CONSISTS OF 1.OUTER THE BLASTOCYST CONSISTS OF 1.OUTER LAYER CALLED TROPHOBLASTLAYER CALLED TROPHOBLAST

2.INNER CELL MASS WHICH GIVES RISE TO 2.INNER CELL MASS WHICH GIVES RISE TO THE EMBRYOTHE EMBRYO

THE TROPHOBLAST ERODES AND DIGEST THE TROPHOBLAST ERODES AND DIGEST THE ENDOMETRIUM NOW CALLED THE ENDOMETRIUM NOW CALLED DECIDUA.DECIDUA.

EARLY DEVELOPMENTEARLY DEVELOPMENT

DEVELOPMENT OF THE DEVELOPMENT OF THE PLACENTAPLACENTA

FORMS FROM TROPHOBLAST WHICH FORMS FROM TROPHOBLAST WHICH DIFFERENTIATES TODIFFERENTIATES TO

1.INNER CYTOTROPHOBLAST1.INNER CYTOTROPHOBLAST

2.OUTER SYNCYTIOTROPHBLAST2.OUTER SYNCYTIOTROPHBLAST

FORMATION OF PLACENTAFORMATION OF PLACENTAEARLY DEVELOPMENTEARLY DEVELOPMENT

TROPHOBLAST PENETRATES THE TROPHOBLAST PENETRATES THE ENDOMETRIUM NOW CALLED DECIDUA.ENDOMETRIUM NOW CALLED DECIDUA.

DECIDUA BASALIS IS UNDERNEATH THE DECIDUA BASALIS IS UNDERNEATH THE CONCEPTUS AND IS INVOLVED IN THE CONCEPTUS AND IS INVOLVED IN THE MATERNAL SIDE OF THE PLACENTA.MATERNAL SIDE OF THE PLACENTA.

CYTOTROPHOBLAST PROLIFERATES AND CYTOTROPHOBLAST PROLIFERATES AND FORM CLUMPS THAT EXTENDS TO THE FORM CLUMPS THAT EXTENDS TO THE SYNCYTIOTROPHOBLAST TO FORM THE SYNCYTIOTROPHOBLAST TO FORM THE PRIMARY VILLI.PRIMARY VILLI.

FORMATION OF PLACENTAFORMATION OF PLACENTALATER DEVELOPMENTLATER DEVELOPMENT

Placenta: Later dePlacenta: Later development velopment Placental growth continues to term Placental growth continues to term

Until week 16 the placenta grows both thickness and Until week 16 the placenta grows both thickness and circumference due to the growth of the chorionic villi with circumference due to the growth of the chorionic villi with accompanying expansion of the intervillous space.accompanying expansion of the intervillous space.

After 16 weeks growth occurs mainly circumferentially.After 16 weeks growth occurs mainly circumferentially.

The placenta at termThe placenta at termCircular, diameter 15-20, thickness~2.5cm at the centre.Circular, diameter 15-20, thickness~2.5cm at the centre.

Weight~500g (the ratio of fetal: placental weight at term is Weight~500g (the ratio of fetal: placental weight at term is about 6:1) It occupies about 30% of the uterine wall at about 6:1) It occupies about 30% of the uterine wall at term and has two surfaces: term and has two surfaces:

Fetal surface Fetal surface Covered by a smooth, glistening amnion with the Covered by a smooth, glistening amnion with the

umbilical cord usually attached at or near its umbilical cord usually attached at or near its centre.centre.

The branches of the umbilical blood vessels are The branches of the umbilical blood vessels are visible beneath the amnion as they radiate from visible beneath the amnion as they radiate from the insertion of the cord.the insertion of the cord.

The amnion can be peeled off from the underlying The amnion can be peeled off from the underlying chorion except at the insertion of the cord.chorion except at the insertion of the cord.

Maternal surface Maternal surface Has a rough and spongy appearance and is Has a rough and spongy appearance and is

divided into several velvety bumps called the divided into several velvety bumps called the cotyledons (15-20) by septa arising from the cotyledons (15-20) by septa arising from the maternal tissues.maternal tissues.

Each cotyledon may be supplies by its own spiral Each cotyledon may be supplies by its own spiral artery.artery.

Numerous small greyish spots may be visible on Numerous small greyish spots may be visible on the maternal surface representing calcium the maternal surface representing calcium deposition in degenerated areas.deposition in degenerated areas.

Umbilical cordUmbilical cordVascular cable that connect the fetus to the placenta.Vascular cable that connect the fetus to the placenta.

Varies from 30 to 90cm long , covered by amniotic Varies from 30 to 90cm long , covered by amniotic epithelium.epithelium.

Contains two umbilical arteries and one umbilical vein Contains two umbilical arteries and one umbilical vein embedded into the Wharton's jell.embedded into the Wharton's jell.

The arteries carry deoxygenated blood from the fetus to the The arteries carry deoxygenated blood from the fetus to the placenta and the oxygenated blood return to the fetus via placenta and the oxygenated blood return to the fetus via the umbilical vein.the umbilical vein.

In a full-term fetus, the blood flow in the cord is In a full-term fetus, the blood flow in the cord is approximately 350ml\min approximately 350ml\min

PRIMARY VILLI BRANCHES PRIMARY VILLI BRANCHES EXTENSIVELY INTO SECONDARY AND EXTENSIVELY INTO SECONDARY AND TERTIARY VILLI AND FINALLY TERTIARY VILLI AND FINALLY CHORION FRONDOSUM.(fetal portion CHORION FRONDOSUM.(fetal portion of the placenta)of the placenta)MORE INVASION OF THE DECIDUA MORE INVASION OF THE DECIDUA BASALIS TAKES PLACE,WITH THE BASALIS TAKES PLACE,WITH THE FORMATION OF THE COTYLEDON(15-FORMATION OF THE COTYLEDON(15-20)20)

PLACENTAL FUNCTIONPLACENTAL FUNCTION1. LUNG FUNCTION-GASEOUS EXCHANGE1. LUNG FUNCTION-GASEOUS EXCHANGE2.KIDNEY FUCTION-EXCRETION OF 2.KIDNEY FUCTION-EXCRETION OF HYDROGEN IONS AND BREAKDOWN HYDROGEN IONS AND BREAKDOWN PRODUCTS OF OTHER SUBSTANCESPRODUCTS OF OTHER SUBSTANCES3. GI. FUNTION-NUTRIENT FUNCTION3. GI. FUNTION-NUTRIENT FUNCTION4.HORMONE PRODUCTION4.HORMONE PRODUCTION5.IMMUNE FUNCTION-TRANSFER OF 5.IMMUNE FUNCTION-TRANSFER OF IMMUNOGLOBULINS TO THE FETUSIMMUNOGLOBULINS TO THE FETUS6.LIVER FUNCTION-DETOXIFICATION OF 6.LIVER FUNCTION-DETOXIFICATION OF DRUGSDRUGS

PLACENTAPLACENTA