Prenatal development

what is the shared feature of chordates?

all have spinal cords

when was the microscope invented?

1950s

what does scala naturae mean?

great chain of being (species are fixed and arranged hierarchally)

what did Nicolaas Hartsoeker do?

used a microscope to see a embryo/foetus and came up with preformation theory

what development occurred in the 19th century?

improvements in optics demonstrated that embryonic development did not involve simple processes of growth but also substantial differentiation

what is a teleological view?

what is recapitulation theory?

embryos took the form of a less evolved version of the species/the development of an animal from an embryo to an adult mirrors the evolution of that animal

how did photographs change the previous understanding of prenatal development?

showed that early embryos are much more differentiated across species (disproves recapitulation theory)

what are the stages of prenatal (antenatal) development?

• the germinal period (conception to implantation)

• the embryonic period (implantation to approx. 2 months)

• the foetal period (2 months to birth)

what is a morula (germinal period)?

the collection of cells formed in the first few days after conception

what is a blastocyst (germinal period)?

the mass of cells 5 days after conception

what occurs after the first two weeks of prenatal development?

cell differentiation

what are the layers of the nervous system?

• ectoderm

• mesoderm

• endoderm

what is the ectoderm for?

• nervous system

• cornea and lens of eye

• epidermis of skin

• epithelial lining of mouth and rectum

what is the mesoderm for?

• skeletal system

• circulatory system

• lymphatic system

• muscular system

• excretory system

• reproductive system

• dermis of skin

• lining of body cavity

what is the endoderm for?

• epithelial lining of the digestive tract, respiratory tract, reproductive tract and urinary tract

• liver

• pancreas

• thyroid

• parathyroids

• thymus

what occurs at the third week of prenatal development?

• eye is apparent

• brain is beginning to bulge

• heart and liver are forming

• scaffolds for individual vertebrae

• there is a rudimentary tail

• ‘buds’ where arms and legs will be

what occurs at 7 weeks of prental development?

• individual fingers and toes are apparent

• gut is developing

what occurs at 2 months of prenatal development?

• limbs are well-formed

• the brain has expanded substantially

what occurs at 4 months of prenatal development?

• ears are taking their final form

• eyelids are well-developed

• foetus is capable of movement

• can react to touch and sound (250-500 Hz)

what occurs at 8 months of prenatal development?

• genitalia are nearly fully formed and apparent

what is aneuploidy?

the condition of having fewer or more than the usual number of chromosomes

what is trisomy 21?

extra 21st chromosome that causes Down’s syndrome

what is trisomy 18?

an extra 18th chromosome that causes Edwards syndrome

what is trisomy 13?

an extra 13th chromosome that causes Patau syndrome

what are teratogens?

any agent or substance which can cause malformation of an embryo/birth defects (includes drugs, alcohol, tobacco, and other environmental agents)

what was the thalidomide tragedy?

a drug developed to treat headaches, insomnia and morning sickness that caused babies to be born with severely misshapen limbs

what problems can be caused by foetal alcohol syndrome (FAS)?

• microcephaly (the baby’s head is much smaller than expected)

• vision and hearing problems

• learning difficulties

describe the results of study by DeCasper and Spence

babies were able to differentiate between a story their mothers read during late pregnancy and a new stories (babies showed preference for familiar over new stories)