OOGENESIS

BEFORE BIRTH…

↓

Primordial Germ Cells (developed in Epiblast; 2nd

Week)

↓

MIGRATES TO Yolk Sac

↓

MIGRATES TO Developing Gonads (End of 5th

Week)

↓

Oogonia (2N)

↓

DIVIDES (by mitosis) TO FORM Primary Oocyte

↓

Mitosis results to INCREASE NO. OF OOGONIA AND

PRIMARY OOCYTE

↓

TOTAL NO. GERM CELLS REACHES MAXIMUM (7

MILLION)

↓

SO, CELL DEATH BEGINS (OOGONIA AND PRIMARY OOCYTE

BECOMES ATRETIC)

↓

Surviving Primary Oocytes undergo MEIOSIS I PROPHASE I

DIPLOTINE STAGE (1st arrest)

↓

BIRTH…

↓

600,000-800,000 Primary Oocyte

↓

↓

CHILDHOOD…

↓

Primary oocyte becomes Atretic

↓

BEGINNING PUBERTY…

↓

40,000 Primary Oocyte, fewer than 500 will be ovulated

↓

↓

PUBERTY…

↓

↓

↓

↓

↓

MEIOSIS I CONTINUES AND FINALLY COMPLETED

↓

Secondary Oocyte + 1st

Polar Body

↓

METAPHASE II OF MEIOSIS II (2ND

Arrest)

↓

Fertilization””/ No Fertilization

↓

MEIOSIS II CONTINUES AND FINALLY COMPLETED/

secondary oocyte degenerates

FOLLICLE MATURATION

BEFORE BIRTH…

↓

↓

↓

Primary Oocyte surrounded by thin layer of follicular cells

↓

Primordial Follicle

↓

↓

↓

↓

↓

BIRTH…

↓

(FSH) Surrounding follicular cells change from flat to cuboidal and

gradually become stratified epithelium forming GRANULOSA CELLS.

↓

GRANULOSA CELLS secrete glycoproteins forming ZONA

PELLUCIDA

↓

Primary Follicle

↓

Cells of THECA FOLLICULA organize into THECA INTERNA and

THECA EXTERNA, formation of Antrum

↓

PUBERTY…

↓

Secondary Follicle (LH AND FSH)^^^^

↓

As Antrum enlarges, granulosa remain intact, thus forming CUMULUC

OOPHORUS

↓

Graafian Follicle (surge in LH)

OVARIAN CYCLE

HYPOTHALAMUS

↓

GnRH

↓

GONADOTROPINS

↓

FSH^^

↓

Stimulates growth and maturation of GRANULOSA CELLS

↓

GC Together with THECA INTERNA

↓

Produce ESTROGEN^^

↓

Estrogen stimulates Anterior Pituitary Gland

↓

Produce LH^^

↓

Stimulates FOLLICULAR CELLS

↓

Produce PROGESTERONE

^^FSH

↓

Nourishes the follicular cells of PRIMORDIAL FOLLICLE,

saving the 25-20 Primary follicle from dying and become

atretic

^^ESTROGEN

↓

Uterine Endometrium enter FOLLICULAR/PROLIFERATIVE

PHASE

/ Thinning of cervix mucus to allow passage of sperm

^^LH

↓

Maturation promoting factor / Follicular Rupture and

Ovulation

↓

Maturation of secondary follicle and completion of Meiosis

I

^^^^ OVULATION (Follicular/ Proliferative Phase)

ESTROGEN

↓

Maturation of Secondary Follicle

↓

LH SURGE

↓

Secondary follicle forms into Graafian follicle

↑ Collagenase activity/ ↑Prostaglandins level

↓

Digestion of Collage fibers surrounding the follicles/ Local

muscular contraction in Ovarian walls

↓

Uterine Tube contract Rhythmically

↓

The PRIMARY OOCYTE is extruded from the ovary

together with cumulus oophorus

↓

Fimbrae sweeps over the surface of ovary

↓

SECONDARY OOCYTE is propelled by peristaltic

movement or contraction of Uterine Tube

↓

SECONDARY OOCYTE on uterine tube

↓

Cumulus Oophorus rearrange around the zona pellucida

↓

Forming CORONA RADIATA**

“”FERTILIZATION

Sperm

↓

Passes the Vagina

↓

Passes the Cervix

↓

Muscular contraction of uterus and uterine tube

Uterine tube (2 to 7 hours)

↓

Isthmus of Uterine tube

↓

(Sperm becomes less motile and cease their migration)

↓

CUMULUS OOPHORUS produce chemo-attractants

stimulating motility of sperm

↓

Sperm in AMPULLA

↓

CAPACITATION

(conditioning of the female reproductive tract; involves

epithelial interaction between sperm and mucosal surface

of the tube)

↓

Glycoprotein coat and seminal plasma proteins are

removed from the acrosome of spermatozoa

↓

SPERM passes through

CORONA RADIATA

↓

Acrosome reaction

↓

Sperm passes through ZONA PELLUCIDA

(Alters the property of ZONA Pellucida, preventing other

sperm from entering)

↓

FUSION OF SPERM AND EGG CELL MEMBRANES

**CORPUS LUTEUM (SECRETORY PHASE)

If oocyte is not fertilized…

Remains of the Ruptured Follicle (GRANULOSA CELLS +

THECA INTERNA)

↓

Vascularized by surrounding vessels

↓

Develops into LUTEAN CELLS

↓

CORPUS LUTEUM

↓

CORPUS LUTEUM reaches maximum development

approx. 9 days after ovulation

↓

CORPUS LUTEUM shrinks and produce PROGESTERONE

↓

Becomes CORPUS ALBICANS

↓

Venules and sinusoidal space become packed with blood

cells/ extensive diapedesis in blood tissues

↓

Shedding of Endometrium (Menstruation)

If oocyte is fertilized…

Remains of the Ruptured Follicle (GRANULOSA CELLS +

THECA INTERNA)

↓

Vascularized by surrounding vessels

↓

Develops into LUTEAN CELLS

↓

CORPUS LUTEUM

↓

CORPUS LUTEUM does not degenerate

(Under influence of HCG)

↓

Develops into CORPUS LUTEUM of PREGNANCY

↓

Produce PROGESTERONE (until end 4th

month that the

uterus is ready for implantation)

↓

IMPLANTATION

↓

Uterine glands and arteries become coiled and tissues

become succulent

CLEAVAGE

Uterine Tube…

↓

2 Cell Stage

↓

4 Cell Stage (formation of blastomeres)

↓

COMPACTION (Blastomeres maximize their contact with

each other; segregates inner cell mass from outer cell

mass)

↓

8 Cell Stage

↓

16 Cell Stage – Morula

↓

Morula enters Uterine Cavity…

↓

Fluid begins to penetrate zona pellucida

↓

Forming BLASTOCOELE

↓

Formation of inner cell mass and outer cell mass

↓

BLASTOCYST

↓

Zona pellucida disappears

↓

IMPLANTATION (Trophoblastic cells penetrate epithelial

cells of Uterine Mucosa)

SPERMATOGENESIS

PRIMORDIAL GERM CELLS is at Sex cords At Birth

↓

Before Puberty… Sex cord obtain lumen and form Seminiferous tubules

↓

PG develops into SPERMATOGONIAL STEM CELLS

↓

Differentiate to SPERMATOGONIA TYPE A

↓

Divides by mitosis to form SPERMATOGONIA TYPE B

↓

Divides by mitosis to form PRIMARY SPERMATOCYTE

↓

Meiosis I prolonged

↓

Puberty

↓

Meiosis I completed

↓

Forms SECONDARY SPERMATOCYTE

↓

Meiosis 2 completed

↓

Forms SPERMATIDS

↓

Spermiogenesis (1. Formation of acrosome, 2. Condensation of nucleus, 3. Formation of neck, midpiece and tail and 4. Shedding of cytoplasm)

↓

Mature Spermatozoa

↓

Lumen of Seminiferous Tubules

↓

Epididymis

2nd

Week of Development (FORMATION OF BILAMINAR DISC)

Day 8… Day 9…

Day 11 and 12…

Day 13…

Blastocyst attaches its outer cell mass in the epithelium of Endometrial Stroma Blastocyst forms: o Trophoblast (Outer Cell Mass)

Cytotrophoblast

(mononucleated)

Syncytiotrophoblast

(multinucleated)

o Embryoblast (Inner Cell Mass)

Hypoblast

(Cuboidal cells) Epiblast

(Columnar cells)

Amnioblast

o Blastocyst cavity

Blastocyst is partially embedded in the endometrial stroma

Penetration defect is closed by FIBRIN COAGULUM

Appearance of LACUNAE in

syncytiotrophoblast

Blastocyst cavity becomes PRIMITIVE YOLK SAC

Hypoblast forms the EXOCOELOMIC MEMBRANE

(Heuser’s Membrane) – lining of primitive yolk sac

Blastocyst is completely embedded in endometrial stroma

Surface epithelium almost entirely covers the original defect in the uterine wall

Syncytiotrophoblast penetrate deeper into the stroma and erodes endothelial lining → Maternal blood enters lacunae → Establishment of UTEROPLACENTAL CIRCULATION

Exocoelomic Membrane becomes EXTRAEMBRYONIC MESODERM

o SOMATOPLEUR (Somatic

Mesoderm) o SPLANCHNOPLEUR (Visceral

Mesoderm)

Primitive Yolk Sac becomes the SECONDARY/ DEFINITE YOLK SAC

Extraembryonic coelom expands to form CHORIONIC CAVITY

3rd

WEEK (GASTRULATION & NEURULATION)

Day 14 Day 16 - 18

Formation of PRIMITIVE STREAK

Migration of Epiblast cells o Towards the hypoblast – ENDODERM o Epiblast and newly created endoderm – MESODERM o Remains in the epiblast – ECTODERM

*These cells spread laterally and cranially

Formation of NOTOCHORD (Basis of axial skeleton)

Elongation o Cranial end (from prechordal plate) o Caudal end are added (in primitive pit) o Primitive pit forms indentation in the epiblast – neurenteric canal

temporarily connects the amniotic and yolk sac cavities o CLOACAL MEMBRANE is formed at the caudal end

Mesoderm differentiates into: o PARAXIAL MESODERM (midline) o LATERAL PLATE MESODERM (lateral)

Mesoderm covering the Amnion – Somatic or Parietal Mesoderm

Mesoderm covering the Yolk Sac – Splanchnic or Visceral Mesoderm

Both mesoderm forms the INTRAEMBRYONIC CAVITY o INTERMEDIATE MESODERM (connects paraxial and lateral plate mesoderm)

NEURULATION

Day 19 Day 20 Day 23 Day 25 Day 28

Formation of NEURAL

PLATE

Neuroectoderm becomes elevated forming the NEURAL FOLDS

Neural folds fuse cranially and caudally forming the NEURAL TUBE

Closure of the ANTERIOR NEUROPORE (18 –

20 somite stage)

Closure of POSTERIOR NEUROPORE (25

somite stage)

4th

WEEK (ORGANOGENESIS)

ECTODERM

NEURAL TUBE NEURAL CREST CELLS

o Cranial region – forms the BRAIN VESICLES Prosencephalon (FOREBRAIN)

o Telencephalon – CEREBRUM o Diencephalon – OPTIC CUP, THALAMUS, HYPOTHALAMUS and

EPIPHYSIS

Mesencephalon (MIDBRAIN)

RHOMBOCEPHALON (HINDBRAIN) o Metencephalon – CEREBELLUM, PONS o Myelencephalon – MEDULLA OBLONGATA

o Caudal region – forms the SPINAL CHORD

They migrate into :

o CRANIAL NEURAL FOLDS to form: CRANIOFACIAL SKELETON NEURONS FOR CRANIAL GANGLIA GLIAL CELLS

o Mesoderm in 2 pathways: DORSAL PATHWAY

MELONOCYTE

VENTRAL PATHWAYS

SENSORY GANGLIA

ENTERIC NEURONS

SCHWANN CELLS

ADRENAL MEDULLA CELLS

MESODERM

PARAXIAL MESODERM LATERAL PLATE MESODERM INTERMEDIATE MESODERM

SOMITES

SOMITOMERES Somatic mesoderm Splanchnic Mesoderm

Metanephric Mesodern

Ureteric Bud

SCLEROTOME DERMATOME MYOTOME

o Ventromedial forms

the cartilage, tendons and bones

o Vertebrae Primary Curves

• THORACIC CURVE • SACRAL CURVE

Secondary Curves • CERVICAL CURVE

(develops when a child learns to hold up his head)

•LUMBAR CURVE (develops when a child learns to walk)

o Intervertebral disc

o Together with Lateral Plate mesoderm forms the COSTAL CARTILAGE

o BONY PART OF THE

RIBS

o Remains in the middle –forms the dermis of back

o Dorsomedial & Ventrolateral –forms the segmental muscles

o Cranially (in

association with neural plate) – forms the NEUROMERES

and then into MESENCHYME OF THE HEAD

o Caudally to form the

SOMITES which will form the AXIAL SKELETON

w/ ectoderm – dermis of skin in body wall, connective tissue of limbs

w/ sclerotome and myotome – costal cartilage, limb muscles and most body wall muscles

surround in intraembryonic cavity – mesothelial and serous membranes

MANUBRIUM, STERNEBRAE XIPHOID PROCESS

Together with

neural crest cells form SMOOTH MUSLES

w/ embryonic endoderm – wall of Gut Tube

Hemangioblast →blood islands → blood cells

o Stroma of glands

o Visceral muscles,

connective tissue and Peritoneal components of the gut

o Bowman’s

capsule

o Proximal Convulated Tubule

o Loop of Henle

o Distal Convulated Tubule

o Ureter

o Renal

Pelvis

o Major

Calyx

o Minor Calyx

DERMOMYOTOME

Ventrolateral lip o INFRAHYOID, ABDOMINAL

WALL, LIMB MUSCLES

Dorsolateral lip o Muscles of the back,

shoulder girdle and intercostal muscles

ENDODERM

FOREGUT MIDGUT - HINDGUT

Dorsal portion of the Respiratory Diverticulum forms the ESOPHAGUS

Fusiform dilation of the foregut forms the

STOMACH

The terminal part of the foregut and the cephalic part of the midgut forms the DUODENUM

Outgrowth of the endodermal epithelium at the

distal end of the foregut forms the LIVER

Small ventral outgrowth formed by the bile duct forms the GALLBLADDER

o Formed from the two buds of the endodermal

lining of duodenum is the PANCREAS

o Epithelial lining of digestive tract o Hepatocytes, endocrine and exocrine glands

of pancreas

Cephalic limb of the primary intestinal loops develop into DISTAL PART OF DUODENUM, JEJUNUM AND PART OF ILEUM

Caudal limb of the primary intestinal loops

becomes the LOWER PORTION OF ILEUM, CECUM, APPENDIXASCENDING COLON AND PROXIMAL 2/3 OF TRANSVERSE COLON

*formed from rapid elongation of the gut and its mesentery

o

DISTAL 1/3 OF TRANSVERSE COLON

DESCENDING COLON

SIGMOID

RECTUM

UPPER PART OF ANAL CANAL (derived from

endoderm of hindgut and ectoderm of proctodeum)

INTERNAL LINING OF BLADDER AND

URETHRA

*degeneration of cloacal membrane establish continuity between upper and lower part of anal canal

Orientation of BODY PARTS

LIMBS STOMACH DUODENUM

o FORELIMBS (1

st)

Rotates 90 degree laterally

Extensor muscles lie laterally and posteriorly, thumbs on lateral side

o HINDLIMBS (2nd

) Rotates 90 degree medially

Extensor muscles at the anterior, toes at the medial side

SEGMENTATION OF THE LIMBS First circular constriction separates distal segment

(foot/hand) from proximal segment (legs) Second circular constriction divides proximal

portion into two segments (the thigh and the legs)

90 DEGREE CLOCKWISE ROTATION AROUND THE LONGITUDINAL AXIS

o Left side of the stomach face anteriorly o Right side of the stomach face posteriorly o Greater Curvature of the Stomach (formed

because posterior wall of stomach grows faster than anterior wall)

ROTATION ON THE ANTEROPOSTERIOR AXIS

o Caudal or pyloric part moves right, upward o Cephalic or cardiac portion moves left

downward

ROTATION OF STOMACH ON ANTEROPOSTERIOR AXIS

o Duodenum forms a C shaped loop and rotates to the right

o Swings duodenum from midline to right of abdominal cavity

o FINGERS and TOES Distal portion thickens and forms APICAL ECTODERMAL RIDGE (AER)

AER inducts the adjacent mesenchyme causing it to remain undifferentiated, rapidly, proliferating cells called PROGRESSIVE ZONE Cell death in AER separate ridges into 5 parts o FEET/HANDS

Terminal portion becomes flattened to form HAND AND FOOT PLATES

PHARYNGEAL ARCH

1ST

PHARYNGEAL ARCH 2ND

PHARYNGEAL ARCH

(Hyoid arch)

3RD

PHARYNGEAL ARCH 4TH

AND 6TH

PHARYNGEAL ARCH

o Maxillary Process (Dorsal)

PREMAXILLA, MAXILLA, ZYGOMATIC BONE, part of TEMPORAL BONE

o Mandibular Process (Ventral) INCUS, MALLEUS

o TRIGEMINAL NERVE

o STAPES, STYLOID PROCESS,

TEMPORAL BONE, STYLOHYOID LIGAMENT, LESSER HORN and UPPER PART OF THE BODY OF HYOID BONE

o FACIAL NERVE

o LOWER PART OF THE BODY

OF HYOID BONE, GREATER HORN OF HYOID BONE

o GLOSSOPHARYNGEAL NERVE

o THYROID, CRICOID,

ARYTENOID, CORNICULATE CUNEIFORM CARTILAGE OF LARYNX

o SUPERIOR LARYNGEAL BRANCH OF VAGUS NERVE (4

TH Arch)

o RECURRENT LARYNGEAL BRANCH OF VAGUS NERVE (6

TH Arch)

1ST

PHARYNGEAL CLEFTS o EXTERNAL AUDITORY MEATUS

PAHRYANGEAL POUCH

1ST

PHARYNGEAL POUCH 2ND

PHARYNGEAL POUCH 3RD

PHARYNGEAL POUCH 4TH

PHARYNGEAL POUCH

o TYMPANIC MEMBRANE

(Distal) o EUSTACHIAN TUBE

(Proximal)

Palatine Tonsils

o INFERIOR PARATHYROID

GLAND (Dorsal) o THYMUS (Ventral)

o SUPERIOR PARATHYROID GLAND (Dorsal)

o ULTIMOBRANCHIAL BODY (Ventral)

Parafollicular Cells of Thyroid Gland

Calcitonin

TONGUE

MESODERM OF 1ST

PHARYNGEAL ARCH

MESODERM OF 2ND

, 3RD

AND 4

TH PHARYNGEAL ARCH

Posterior Part of the 4TH

Arch

LATERAL LINGUAL SWELLING

1ST

MEDIAL SWELLING

2ND

MEDIAN SWELLING 3rd

MEDIAN SWELLING

Anterior 2/3 of TONGUE

Anterior 1/3 of TONGUE

Posterior Root of TONGUE EPIGLOTTIS

MAXILLARY PROMINENCE FRONTONASAL PROMINENCE

MANDIBULAR PROMINENCE

Merge with 2 MEDIAL NASAL PROMINENCE

Merge with the INTERMAXILLARY SEGMENT Merge across the midline

UPPER LIP

UPPER JAW COMPONENT

LABIAL COMPONENT

PALATAL COMPONENT

LATERAL NASAL PROMINENCE

MEDIAL NASAL PROMINENCE

LOWER LIP

4 INCICOR TEETH

PHILTRUM OF UPPER LIP

TRIANGULAR PRIMARY PALATE

SIDE OF NOSE AND CHEEKS

CREST AND TIP OF NOSE

2nd

MONTH TO BIRTH

Month Development

2nd

Month (5

th week – 8

th week)

LIMBS AND HEAD

INCREASE IN HEAD SIZE FORELIMBS APPEAR as paddle shaped buds HINDLIMBS appear later

3RD

Month ( 9th

– 12th

week) FULL DEVELOPMENT OF ORGANS

Slowdown in the growth of the head compared to the rest of the body FACE becomes more HUMAN –LIKE EYES from lateral position moves to the ventral portion of the head Ears comes to lie at their definite position in the head Limbs reach their relative length Primary ossification are present in long bones and skull External genitalia develop to such degree that the sex of the fetus can be determined Large swelling (Herniation) has withdrawn into the abdominal cavity

4th

( 13th

– 16th

weeks) LENGTH

Fetus lengthens rapidly Weight increase a little Fetus is covered with fine hair (lanugo), eyebrows are visible

5th

Month (17th

– 20th

weeks) WEIGHT

Movements of fetus can be felt by the mother Weight increase rapidly Fetus swallows its own amniotic fluid (400 mL a day) – FETAL urine is added daily to the amnion

6th

Month (21ST

24TH

weeks) RED SKIN

Skin is reddish and wrinkled because lack of underlying connective tissue Fetus born in this month cannot survive since Respiratory and Nervous System has not yet sufficiently differentiated

7 Months (25th

- 28th

weeks) WHITE SKIN

Fetus obtains well rounded contours as a result of fat deposition The skin is covered with whitish fatty substance (Vernix caseosa) composed of secretory products of sebaceous glands

9th

Month ( 33th - 36 weeks) FETUS READY FOR DELIVERY

Skull has the largest circumference of all parts of the body

CHANGES IN THE TROPHOBLAST/ PLACENTA

2nd

MONTH 4TH

MONTH 5TH

MONTH

Cytotrophoblastic cells invades

(ENDOVASCULAR INVASION) the terminal ends of SPIRAL ARTERIES

This transforms SPIRAL ARTERIES from small diameter, high resistance vessels to large diameter, low resistance vessels

Spiral arteries release blood into the INTERVILLOUS SPACE – derived from lacunae of Syncytiotrophoblast; filled with maternal blood

Cytotrophoblastic cells and connective tissue cells

disappears due to increase in diameter of villi The SYNCYTIUM and ENDOTHELIAL WALL OF

BLOOD VESSELS are the only layers that separate maternal and fetal circulation

Villi covers the surface of the CHORION Villi grow and expand to form CHORION

FRONDOSUM

Villi on abembryonic region degenerate forming CHORION LEVAE

CHRORION LEVAE comes in contact with DECIDUA PARIETALIS on the opposite side of the uterus and fuse, obliterating the uterine lumen

Amnion expands, and come in contact with Chorion, obliterating the CHORIONIC CAVITY; yolk sac shrinks and gradually obliterated

Placenta produce: o PROGESTERONE to maintain pregnancy

(synthesized in SYNCYTIAL TROPHOBLAST) o ESTROGEN just before end of pregnancy to

promote uterine development and growth of mammary glands

o hCG to maintain Corpus luteum o Placental lactogen which gives fetus priority on

maternal blood glucose and makes mother diabetogenic; promotes breast development for

PLACENTA ENLARGES with growth of the fetus

and expansion of Uterus not due to further penetration into maternal tissues but due to arborisation of existing villi

PARTURITION

EFFACEMENT

DELIVERY OF THE FETUS

DELIVERY OF THE PLACENTAL MEMBRANES

o Uterine contracts, amniotic sac s forced against the cervical canal like a wedge

o If memebrane is ruptured, pressure will be exerted by the presenting part of the fetus, usually the HEAD

o Uterus contracts o Increased intraabdominal pressurefrom

contraction of Abdominal Muscles

o Uterine contractions o Abdominal muscle contraction

PLACENTA

Placenta is composed of:

CHORION FRONDOSUM (Fetal Component) – derived from TROPHOBLAST

and EXTRAEMBRYONIC MESODERM

o Bordered by CHORIONIC PLATE

DECIDUA BASALIS (Maternal Component) – derived from UTERINE

ENDOMETRIUM

o Bordered by DECIDUAL PLATE

o Contains compartments called COTYLEDONS – maintain its contact with

INTERVILLOUS SPACE through DECIDUAL SEPTA

Function:

Exchange of gases (simple diffusion)

Exchange of nutrients

Transmission of Maternal Antibodies

Hormone Production (hCG , progesterone, estrogen and placental lactogen)

Full Term Placenta:

Discoid

15 to 25 cm in diameter

3 cm thick

Weighs 500 to 600 grams

Form from uterine wall at birth

Expelled 30 minutes after birth

On MATERNAL SIDE:

Contains 15 TO 20 cotyledons covered by decidua basalis

On FETAL SIDE:

PLACENTA is covered by CHORIONIC PLATE

CHORIONIC VESSELS converge toward the umbilical cord

CHORION is covered by AMNINON

4 Layers of Placental Membrane:

Endothelial lining of Fetal Vessels

Connective Tissue on Villous Core

Cytotrophoblastic layer

Syncytium

The Amniotic Fluid

Derived from maternal blood

Produced by amniotic cells

Clear, watery fluid replaced every 3 hours

Normal amount:

o 10 weeks – 30 mL

o 20 weeks – 450 mL

o 37 weeks – 800 – 1000 mL

Function:

Absorbs jolt

Prevents adherence of embryo to the amnion

Allow fetal movements

The Umbilical Cord

Distally, contains :

o Yolk Stalk

o Umbilical vessels

Proximally contains:

o Intestinal loop

o Remnant of Allantois

Resource: Langman’s MedicalEmbryology, 11th

Edition

Compiled and condensed by: Ma. Theresa Monje

August 21, 2012