Sections 53.4-53.6

What He$# is Organogenesis?

Blah…Blah...Blah More InfoCell-Signaling Molecules and Transcription help

the genetic control of organogenesis in Vertebrates and Invertebrates.

CELLS…CELLS…CELLSCell Determination- a cell’s location in the

developing embryo determines its fate..Induction- a cells fate can be established by

inheritance of cytoplasmic determinant from the mother and by interaction of cells…

Nonporous Barrier- Prevents Induction Porous Filter- Permits Induction

Development and Stuff…

Vertebrate Axis FormationThe dorsal-ventral axis is determined by the

Spemann organizer.. Organizers are a cluster of cells that produce

gradients of diffusible signal molecules, conveying positional information to other cells..

Wnt genes encode a large family of cell –signaling proteins that affect the development of a number of structures in both vertebrates and invertebrates..

The Sperm Meets the Egg and a Human Develops!!!!

“Random Fact” Human development from fertilization to birth takes an average of 266 days or about 9 months…This time is divided into three period called

Trimesters.. First Trimester…Second…and Third

First Trimester

1st Trimester Continued….. The Second Month The Third Month

Organogenesis continues….The miniature limbs of the

embryo assume their adult shapes. The arms, legs, knees,

elbows, fingers, and toes can all be seen, as well as a short bone tail..

Major organs such as the liver, pancreas, and gallbladder become evident.

The 9th week the embryo becomes a fetus.

All of the major organs in the body has been set in there proper locations …

The Nervous System Develops….

Shows Facial Expressions and starts primitive reflexes…

(hCG)declines and the corpus lutem regresses as a result.

** High levels of estadioal and progesterone in the blood during pregnancy continues to inhibit the release of FSH and LH, thereby preventing ovulation

Conception

Blastocyst Gestational Sac

Ultraso

und

12 weeks

Second TrimesterBones EnlargeA rapid Heartbeat can

be Heard.The fetus weighs about

1.3lbs is about 1 ft long.The fetus cannot

survive outside the uterus without special medical interventions…

Can tell if it a boy or girl??

Third Trimester Organs Mature to the

Point at which the baby can survive outside the womb.

The weight of the fetus doubles several times…

Major Nerve Tracts in the brain is formed…Continues to develop

and produce new neurons for months after birth..

Birth……Birth is initiated by secretion of corticosteroids

from the fetal adrenal cortex that induce prostaglandin, which cause contractions.

Estadioal also stimulates the uterus to produce ore oxytocin receptors which it becomes sensitive to.

Working together oxytocin and prostaglandin further stimulate uterine contractions, forcing the fetus downward labor.

After birth, continuing uterine contractions expel the placenta and associated membranes, called afterbirth

http://youtube.com/watch?v=GB3xu2krjuc&feature=related

Milk is Coming Out of My Br@#%!!This process is called lactation or milk

production. It occurs in the alveoli of mammary glands when they

are stimulated by the prolactin.. During pregnancy high levels of progesterone

stimulates the development of alveoli and estadioal stimulate the development of the alveolar ducts.

When the placenta is discharge after birth…progesterone and estadioal declines as prolactin is secrete and milk is made..

The pathway In which milk is released is called the milk-let down reflex.

Colostrums is the first milk produced after birth…it hold nutritious and is rich in maternal antibodies.

Postnatal Development in HumansThe growth of infants continue rapidly after

birth..Allometic Growth

A pattern of growth in which different components grow at different rates.