Key Concepts from Lecture on Early Gastrulation and Development

These flashcards cover key concepts from the lecture, focusing on embryonic development stages, structures, and evolutionary significance.

What is the primitive streak?

A feature of mammalian, avian, and reptilian development that marks the beginning of gastrulation.

What is the significance of Henson's node?

Henson's node is the origin of the notochord and is critical for forming the embryonic head.

What defines the process of gastrulation?

Gastrulation is the process where the formation of the three germ layers begins, establishing the embryonic body plan.

What type of cleavage occurs in mammals?

Mammals exhibit radial cleavage.

What are the three primary germ layers formed during gastrulation?

Ectoderm, mesoderm, and endoderm.

What are monotremes?

Monotremes are egg-laying mammals such as the platypus and echidna.

What happens during compaction in early embryogenesis?

Cells become closely packed to form a tight ball of cells known as a morula.

What is the role of cadherins in early development?

Cadherins are proteins that help cells adhere to one another during compaction.

What does the term 'blastocyst' refer to?

A structure formed in the early development of mammals containing an inner cell mass and trophoblast.

Why do birds and reptiles share a similar feature regarding their heart structure?

Many birds and reptiles, including dinosaurs, have a four-chambered heart which is thought to support blood flow to their heads.

In the context of embryonic development, what is a notochord?

A cartilaginous rod-like structure that forms the basis for the vertebral column.

How does gastrulation differ in frogs compared to birds and mammals?

Frogs undergo complete cleavage with a yolk plug, while birds and mammals have surface divisions and do not form yolk plugs.

What is the significance of gene expression in Hox genes?

Hox genes dictate the body plan and structure during embryonic development, being responsible for the regional identity of segments.

What are somites?

Blocks of mesodermal tissue that develop into muscles and vertebrae.

What does 'asymmetry in organ development' refer to?

The difference in structure or morphology between the left and right sides of an organism.

What is the pharyngula stage?

A stage in embryonic development characterized by the presence of pharyngeal folds and notochord, common across chordates.

How does the concept of evolutionary history apply to embryonic development?

Embryonic features reflect shared ancestry, seen in similarities among different vertebrate embryos during early stages.