Download Fetal surface covered by amnion

CONCEPTION AND
BIOPHYSICAL CHANGES
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
OOGENESIS
Ovary gives rise to oogonial cells
First meiotic division – two unequal cells
Second meiotic division – begins at
ovulation
Three polar bodies
One ovum
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-3-A GAMETOGENESIS INVOLVES MEIOSIS WITHIN THE OVARY AND TESTIS. DURING MEIOSIS,
EACH OOGONIUM PRODUCES A SINGLE HAPLOID OVUM ONCE SOME CYTOPLASM MOVES INTO THE POLAR
BODIES.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
SPERMATOGENESIS
Production of sperm begins during puberty
First meiotic division
Primary spermatocyte replicates and divides
Second meiotic division
Secondary spermatocytes replicate and divide
Produce four spermatids
Series of changes
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-3-B GAMETOGENESIS INVOLVES MEIOSIS WITHIN THE OVARY AND TESTIS. EACH
SPERMATOGONIUM, IN CONTRAST, PRODUCES FOUR HAPLOID SPERMATOZOA.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
THE PROCESS OF FERTILIZATION
Sperm and ovum unite to form a zygote
Ova are fertile for 12 to 24 hours
Sperm are fertile for 72 hours
Takes place in the ampulla of fallopian tube
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CONCEPTION
Necessary functional components
a. uterus
b. fallopian tubes
c.
ovaries (eggs)
d. hormones
e. sperm
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PREPARATION FOR FERTILIZATION
Estrogen levels increase peristalsis in
fallopian tubes
Fertilization usually takes place in ampulla
Single ejaculation – 200 to 500 million
spermatozoa
Prostaglandins in semen help transport
sperm
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CHANGES IN SPERM
Capacitation
Removal of plasma membrane and glycoprotein
coat
Loss of seminal plasma proteins
Acrosomal reaction
Release of enzymes
Allows entry through corona radiata
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
AFTER SPERM ENTRY
Additional sperm blocked by zone pellucida
Secondary oocyte completes second meiotic
division, forms nucleus of ovum
Nuclei of ovum and sperm unite
Nuclear membranes disappear
Chromosomes pair up
Sex of zygote determined
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FERTILIZATION
& IMPLANTATION
a.
process over time
Ovum

Fertilized Ovum

Zygote (Pronuclei Stage)

1st Mitotic Division

2-Cell Zygote (1 1/2 days later)

16-Cell Morula (3 days)

58-Cell Blastocyst (4 days)

107-Cell Unilaminar Blastocyst (4 1/2 days)

Several Days Pass Until Bilaminar Blastocyst Implants (6 days)
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FERTILIZATION & IMPLANTATION
Several Days Pass Until Bilaminar Blastocyst Implants (6
days)
b.
c.
d.
double layer development
1)
blastocyst - inner layer - solid
2)
trophoblast - outer layer foraging layer (feeding layer)
implantation
trophoblast to chorion
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-4 A. SPERM PENETRATION OF AN OVUM. THE SEQUENTIAL STEPS OF OOCYTE PENETRATION
BY A SPERM ARE DEPICTED MOVING FROM TOP TO BOTTOM.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-4 B. SPERM PENETRATION OF AN OVUM. SCANNING ELECTRON MICROGRAPH OF HUMAN
SPERM SURROUNDING A HUMAN OOCYTE (750 ). THE SMALLER SPHERICAL CELLS ARE GRANULOSA CELLS
OF THE CORONA RADIATA. SOURCE: USED WITH PERMISSION FROM NILSSON, L. (1990). A CHILD IS BORN.
NEW YORK, NY: DELL PUBLISHING.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PREEMBRYONIC STAGE
First 14 days of human development
Cleavage
Blastomeres form morula
Blastocyst
Develops into embryonic disc and amnion
Trophoblast
Develops into chorion
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
IMPLANTATION
Occurs 7 to 10 days after fertilization
Blastocyst burrows into endometrium
Endometrium is now called decidua
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CELLULAR DIFFERENTIATION
Primary germ layers
Ectoderm
Mesoderm
Endoderm
All tissues develop from primary germ cell layers
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
TABLE 11-2 DERIVATION OF BODY
STRUCTURES FROM PRIMARY CELL
LAYERS
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CELLULAR DIFFERENTIATION (CONT’D)
Embryonic membranes begin to form
Chorion(outerm membrane contribues to
placental development)
Amnion (inner most membranous sac)
Amniotic fluid
Functions –protects against physical force,
maintains temperature, allows fetal movement
Characteristics-clear, slightly yellow, 7001000cc by 3rd trimester,
Abnormal variationsYolk sac-provides early nourshment
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
CELLULAR DIFFERENTIATION (CONT’D)
Umbilical cord
 Body stalk fuses with embryonic portion of placenta
 Provides circulatory pathway from chorionic villi to
embryo
One vein, two arteries
Wharton’s jelly
Delivers oxygenated blood to fetus
 Two arteries
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTA
Metabolic and nutrient exchange
Maternal portion
Decidua basalis and circulation
Fetal portion
Covered by amnion (chorionic villi)
Fetal surface covered by amnion
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTAL DEVELOPMENT
Chorionic villi form spaces in decidua
basalis
Spaces fill with maternal blood
Chorionic villi (provide blood supply to the
embryo)
Syncytium: outer layer
Cytotrophoblast: inner layer
Anchoring villi form septa
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-13 LONGITUDINAL SECTION OF PLACENTAL VILLUS. SPACES FORMED IN THE MATERNAL
DECIDUA ARE FILLED WITH MATERNAL BLOOD; CHORIONIC VILLI PROLIFERATE INTO THESE MATERNAL
BLOOD-FILLED SPACES AND DIFFERENTIATE INTO A SYNCYTIUM LAYER AND A CYTOTROPHOBLAST LAYER.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTAL CIRCULATION
After implantation cells differentiate
Trophoblast invades endometrium
Opens uterine capillaries
Completion of maternal-placentalfetal circulation
About 17 days after conception
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-14 VASCULAR ARRANGEMENT OF THE PLACENTA. ARROWS INDICATE THE DIRECTION OF
BLOOD FLOW. MATERNAL BLOOD FLOWS THROUGH THE UTERINE ARTERIES TO THE INTERVILLOUS
SPACES OF THE PLACENTA AND RETURNS THROUGH THE UTERINE VEINS TO MATERNAL CIRCULATION.
FETAL BLOOD FLOWS THROUGH THE UMBILICAL ARTERIES INTO THE VILLOUS CAPILLARIES OF THE
PLACENTA AND RETURNS THROUGH THE UMBILICAL VEIN TO THE FETAL CIRCULATION.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTAL FACTS
• Size of 8-inch dinner plate
• Consists of 15-20 cotyledons, chorionic villi
branch out from it
• Structure is complete at the end of 12th week
gestation
• Grows till 20th week gestation, covers ½ of
uterine surface
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PLACENTAL FUNCTIONS
 Transfers nutrients
 Diffuses oxygen and carbon dioxide functioning as fetal lungs
 Production of 4hormones
 hCG
 Progesterone
 Estrogens
 hCS/hPL
 Facilitates transfer of metabolic wastes from the fetus to the
maternal ciruclation
 Transfers heat from mother to fetus.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
DEVELOPMENT OF THE FETAL
CIRCULATORY SYSTEM
Maintains blood flow to placenta
Provides fetus with oxygen and nutrients
Removes carbon dioxide and waste products
Blood flows through umbilical vein into abdominal wall of fetus
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FIGURE 11-15 FETAL CIRCULATION. BLOOD LEAVES THE PLACENTA AND ENTERS THE FETUS THROUGH
THE UMBILICAL VEIN. AFTER CIRCULATING THROUGH THE FETUS, THE BLOOD RETURNS TO THE
PLACENTA THROUGH THE UMBILICAL ARTERIES. THE DUCTUS VENOSUS, THE FORAMEN OVALE, AND THE
DUCTUS ARTERIOSUS ALLOW THE BLOOD TO BYPASS THE FETAL LIVER AND LUNGS.
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
EMBRYONIC AND FETAL DEVELOPMENT
Pregnancy averages 10 lunar months
Beginning of last normal menstrual period
to birth
Most born within 10 to 14 days of
calculated date of birth
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
EMBRYONIC STAGE
Day 15 to Week 8
Tissues differentiate into essential
organs
Week 3
Most advanced organ is heart, beginning
to beat; well-arked midbrain flexure
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
EMBRYONIC STAGE (CONT’D)
Week 4
Beginning development of GI tract
Somites develop – beginning vertebrae
Heart develops, begins beating,
circulating blood
Eyes, nose begin to form
Arm, leg buds present
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
EMBRYONIC STAGE (CONT’D)
Week 5-8
 Trachea developed
 Liver produces blood cells
 Trunk straighter
 Digits develop
 Tail begins to recede
 1st indication of ossification
 Definitive muscles well represented
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL STAGE
Week 9 to birth
At 9-11 weeks
Every organ system, structure present
Gestation time
Refining structures-nails appearing, skin
pink
Perfecting function
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 12 3RD LM
Eyelids closed
Tooth buds appear
Fetal heart tones can be heard
Genitals well differentiated
Urine produced
Spontaneous movement occurs
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 16 4TH LM
Head still dominant
Lanugo begins to develop
Blood vessels clearly developed
Active movements present
Fetus makes sucking motions
Fetus swallows amniotic fluid
Fetus produces meconium
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 20 5TH LM
Subcutaneous brown fat appears
Quickening felt by mother
Nipples appear over mammary glands
Fetal heartbeat heard by fetoscope
Brain grossly formed
Nose and ears ossifying
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 24 6TH LM
Eyes structurally complete
Vernix caseosa covers skin
Alveoli beginning to form
Ability to hear
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 28 7TH LM
Testes begin to descend
Lungs structurally mature
Minimum tones
Fleeting movements
Lecithin forming on alveolar surfaces
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 32 8TH LM
Rhythmic breathing movements
Ability to partially control temperature
Bones fully developed but soft and flexible
L/S ratio 2:1
Sense of taste present
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 36 9TH LM
Increase in subcutaneous fat
Lanugo begins to disappear
L/S ratio >2:1
Definite sleep-wake cycles
Skin pink becoming rounded
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FETAL DEVELOPMENT: WEEK 40 10TH LM
Skin appears polished
Lanugo disappears except in upper arms and
shoulders
Hair now coarse and approximately 1-inch long
Fetus is flexed
Strong suck reflex
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
TABLE 11-4 EMBRYONIC AND
FETAL DEVELOPMENT: WHAT
PARENTS WANT TO KNOW
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
FACTORS INFLUENCING DEVELOPMENT
Quality of sperm or ovum
Genetic code
Adequacy of intrauterine environment
Teratogens (any agent that interfere with a
developing embryo)
Organs formed primarily during embryonic
development
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
SIGNS AND SYMPTOMS OF PREGNANCY—THIS
IS IMPORTANT TO KNOW
Presumptive signs of pregnancy (subjective)
• menstrual suppression (amenorrhea, menstruation
may occur after conception)
• nausea, vomiting, and "morning sickness" (due to
increased HCG levels)
• frequency of micturition (uterus stretches base of
bladder)
• tenderness and fullness of the breasts, breast
pigmentation, and discharge (due to increased
progesterone, estrogen)
• "quickening" (usually 18-20 wks. may be 16 wks. in
multigravida)
• fatigue
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
PROBABLE SIGNS (OBJECTIVE)
• Dark blue discoloration of the vaginal mucous membrane known
as CHADWICK'S SIgn
• pigmentation of the skin and abdominal striae (may also occur
in breasts, buttocks, and thighs)
• changes in the size, shape, and consistency of the uterus HEGAR'S SIGN (lower part of the body of uterus much softer
than cervix)
• fetal outline, distinguished by abdominal palpation and
detection of a fetal part vaginally by BALLOTTEMENT (sudden
tap on presenting part makes it rise in amniotic fluid)
• changes in the cervix (GOODELL'S SIGN - cervix softens due to
increased vascularity edema)
• BRAXTON HICKS contractions (painless, cause of false labor)
• positive pregnancy test (increased Hcg levels, blood/serum 8-9
days after ovulation and fertilization and urine test within 2 wks
of gestation)
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig
POSITIVE SIGNS (DIAGNOSTIC)
• fetal heart sounds (audible with Doppler
8-10 weeks gestation, or ultrasound)
• fetal movements felt by examiner
• x-ray- outline of fetal skeleton
• ultrasonic demonstration of the
presence of a conceptus (6-8 wks.
yields most information)
• fetal movements visible
Olds’ Maternal-Newborn Nursing & Women’s Health Across the Lifespan, Ninth Edition
Michele Davidson • Marcia London • Patricia Ladewig