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42 Cards in this Set
- Front
- Back
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Gametogenesis |
Process of producing gametes. Gametes: Sex cells (egg, sperm) Haploid vs. Diploid Meiosis (reduction division) Four sperm or one egg |
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Prenatal Development: Sequence of events |
Fertilization
Implantation Embryonic development Fetal development Birth |
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Egg Release |
One egg per month; appx. day 14 of 28 day cycle Swept into fallopian tube; appx. 3 days to reach uterus Sperm meets egg in fallopian tube; appx. 2-300 sperm can reach egg |
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Capacitation |
Preparation of a sperm through female tract to become capable of fertilization. |
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Acrosome Reaction |
release of enzymes from acrosome to penetrate oocyte. |
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Fertilization |
Sperm and egg join. Blocks to polyspermy: fast block and slow block Egg completes Meiosis II Pronuclei and amphimixis Zygote formed |
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Fast Block vs. Slow Block |
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Pronuclei |
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Amphimixis |
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Prenatal Development |
Conception Gestation Parturition |
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Conception |
Fertilization -Conceptus: all products of conception |
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Gestation |
Pregnancy -Trimesters: 3 month periods *First trimester: 1-12 weeks *Second trimester: 13-24 weeks *Third trimester: 25 weeks to birth |
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Parturition |
Childbirth |
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Biological States of Prenatal Development |
Preembryonic Embryonic Fetal |
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Preembryonic |
Fertilization Cleavage Implantation |
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Embryonic |
-17 days to end of 8 weeks; after 8 weeks, fetus |
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Fetal |
9 weeks to birth |
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Cleavage |
At 3 days. -Blastomeres -Morula -Blastocyst *Trophoblast: placenta *Embryoblast: embryo |
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Implantation |
6 to 7 days post ovulation - Syncytiotrophoblast - Cytotrophoblast |
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Embryonic Stage |
Establishment of 3 primary germ layers Gastrulation Organogenesis |
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Gastrulation |
Cells of epiblast migrate and form 3 primary germ layers - Ectoderm - Mesoderm - Endoderm Formation of primitive streak (1) Invagination ( mesoderm, then endoderm, then ectoderm) (2) |
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Embryonic Stage: During Weeks 3-4 |
Embryo grows and folds around yolk sac Lateral folding -> primitive gut surface covered with ectoderm mesoderm slits -> coelom (cavity) Coelom divided into thoracic and peritoneal cavity by diaphragm |
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Embryonic State: Organogenesis |
- Neurulation: - Pharyngeal pouches: - Somites: * Sclerotome * Myotome * Dermatome At 5 weeks: - Head Bulge - Heart Bulge - Arm and leg buds |
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Extraembryonic Membranes |
- First appear in second week of development - Amnion *Amniotic fluid - Yolk sac * First blood cells *Stem cells of gametogenesis - Allantois * Forms umbilical cord and urinary bladder - Chorion * Fetal placenta |
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Development of Placenta |
-Extensions of syncitiotrophoblast (chorionic villi) penetrate into endometrium *Blood-filled cavity = placental sinus *Extraembryonic mesenchyme -> blood vessels -Umbilical cord *2 arteries *1 vein *Pumped by fetal heart
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Fetal Stage |
End of week 8. - About 3 cm long - Fetus - Organs are developed and become functional - Rapid weight gain - Human characteristics become distinct |
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Spontaneous Abortions |
Early spontaneous abortions - most common - typically within first 3 weeks - mistaken for late period - high percentage of chromosomal defects in spontaneous abortions - may be natural mechanism of selection |
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Birth Defects |
Congenital anomaly Abnormal structure or position of an organ at birth Teratology: The study of birth defects |
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Mutagens and Genetic Anomalies |
Mutation: change in DNA structure Mutagens: environmental agents that cause mutations |
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Karyotype |
Number and appearance of chromosomes in cell Humans have 23 pairs = 46 chromosomes -Not known until 1950s -T.C. Hsu- MD Anderson in Houston |
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Genetic Disorders: Aneuploidy |
Abnormal number of chromosomes |
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Genetic Disorders: Nondisjunction |
Failure to separate one of the 23 chromosomes during meiosis |
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Nondisjunction Disorders: |
• Triplo-X syndrome - XXX • Klinefelter syndrome – XXY • Turner syndrome – XO • Patau syndrome (trisomy-13) • Edward syndrome (trisomy-18) • Down syndrome (trisomy-21) |
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Triplo-X syndrome - XXX |
d |
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Klinefelter syndrome – XXY |
d |
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Turner syndrome – XO |
d |
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Patau syndrome (trisomy-13) |
dd |
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Edward syndrome (trisomy-18) |
d |
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Down syndrome (trisomy-21) |
d |
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Teratogens |
Agents that cause anatomical deformities. -Drugs or other chemicals -Radiation -Infectious diseases Largest effect during weeks 3-8 of development Thalidomide Fetal Alcohol Syndrome (FAS) |
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Thalidomide |
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Fetal Alcohol Syndrome (FAS) |
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