When Sperm Meets Egg

Egg

In females, the sex cells are called eggs. Eggs are produced in sex organs called ovaries. Sex cells – egg An egg is so big that this is how small a sperm looks next to it. nucleus containing chromosomes jelly coat cytoplasm membrane

Sperm Motility

Sperm meets egg

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Cell division

Identical vs. fraternal twins

5 Day Old Human Blastocysts

An embryo forms a plate-like structure called the placenta. The umbilical cord joins the fetus to the placenta. In the placenta, food and oxygen diffuse from the mother’s blood into the blood of the fetus. Carbon dioxide and waste products diffuse from the blood of the fetus to the mother’s blood. How does an embryo get food and oxygen and how does it get rid of waste? The placenta

The Placenta

In the earliest stages of development, a human baby is called an embryo. After the first eight weeks of pregnancy, a human embryo is then called a fetus. At this stage the fetus has all the main human features. The fetus continues to develop and grow inside its mothers’ uterus for a total of 40 weeks. From embryo to fetus

 Conception – 4 weeks  8 weeks  12 weeks  16 weeks  20 weeks  24 weeks  28 weeks  32 weeks  weeks

First trimester Conception – 4 weeks  Less 1/10 inch long  Beginning of spinal cord, nervous system, heart, intestinal system and lungs  Amniotic Sac – clear fluid, in which the unborn baby floats and moves

First trimester 8 weeks  Less than 1 inch  Face forming – eyes, ears, mouth  Arms and legs are moving  Heartbeat detectable

First trimester 12 weeks  3 inches and weighs 1 oz  Moving fingers and toes  Finger prints  Can smile, frown, swallow and urinate

Second trimester 16 weeks  5 ½ inches long, 4 oz  Strong heartbeat  Thin skin  Downy hair over body  Fingernails and toe nails develop

Second trimester 20 weeks  inches  Sucks thumb  Hiccup  Hair, eyelashes and eyebrows  Rolls over fluid

Second trimester 24 weeks  inches 1 ½ lbs  Wrinkled skin  Open eyes  Strong grip

Third trimester 28 weeks  inches, 2 ½ - 3 lbs  Adding body fat  Very active

Third trimester 32 weeks  16 ½ - 18 inches, 4 – 5 lbs  Sleep/awake  Responds to sounds

Third trimester weeks  19 inches 6lbs  Skin less wrinkled  Gaining immunities from mother

Period of prenatal development  Embryonic Period Occurs 2-8 weeks after conception Rate increases of cell division, support systems for the cells form, organs appear  Germinal period Takes place in first 2 weeks after conception Creation of zygote (fertilized egg), cell division attachment of the zygote to the uterine wall

Period of prenatal development  Embryonic Period Occurs 2-8 weeks after conception Rate increases of cell division, support systems for the cells form, organs appear The mass of cells attached to the uterine wall forms three layers and is now called the embryo  Endoderm – inner layer of cells will develop into digestive and respiratory systems  Ectoderm – outer layer of cells will become the nervous systems and sensory receptors (ears, nose, eyes and skin)  Mesoderm – middle layer – will develop into the circulatory system, bones, muscle, excretory system and reproductive system

Period of prenatal development  Fetal Period 2 months of conception Last for 7 months Development is very dramatic

44 First Stage of Childbirth During labor the bottom part of the uterus enlarges occurs during the first stage of labor. The babies head is about 9.5 centimeters therefore the cervix has to extend at about 10 centimeters.

45 Doctor supports baby’s head and shoulders. Doctor supports baby’s head as it exits the uterus. Hold the baby face down clear mouth of mucus and fluids. The Birth

So cute