Embryology 1 Flashcards
What is the main difference between the amniote eggs of birds/reptiles and mammals?
Mammals have an umbilical cord.
What are chordates?
All animals with dorsal nerve cords & notochords.
What characteristics can dusting us vertebrates from other chordates?
- Vertebral column
- Cranium
- Endoskeleton.
Describe Baer Law.
The embryo of a higher animal form never resembles the adult of another animal form, but only its embryo.
Define embryo.
Phase between fertilisation & birth.
What are the structures that make up the amniote egg?
- Amnion
- Allantois
- Shell
- Yolk sac
- Chorion.
What type of cleavage do amphibians undergo?
Radial cleavage.
What type of cleavage do birds undergo?
Meroblastic cleavage.
What type of cleavage do mammals undergo?
Holoblastic cleavage.
Define trophoblasts.
Cells forming the outer layer of a blastocyst which provide nutrients to the embryo and develop into a large part of the placenta.
Define inter cell mass.
The mass of cells inside the primordial embryo that will eventually give rise to the definitive structures of the foetus.
Define blastomeres.
Individual cells that are formed during cleavage stage are called blastomeres.
What structures can the ectoderm form?
- Cornea and lens of eye
- Nervous system
- Tooth enamel.
What structures can the mesoderm form?
- Skeletal system
- Excretory system
- Circulatory & lymphatic system.
What structures can the endoderm form?
- Liver
- Pancreas
- Thymus.
