The topics of individual talks may change interannually. The program is subject to change without notice!

Topics for 2023/2024:

* 1) Introduction to comparative embryology

Introduction of topics of the course.

Comparative embryology as an insight into the past (comparative embryology as a way to reconstruct phylogenetic relationships, comparative embryology vs. molecular phylogeny, from comparative embryology to developmental genetics and evo-devo)

* 2) Traditional invertebrate model organisms in embryology

What is a „model organism“?

Advantages and disadvantages of using model organisms.

Traditional (worm, fly, flour beetle, sea urchins) and less-common invertebrate models

* 3) Traditional vertebrate model organisms in embryology

Traditional (mouse, chick, frog, zebrafish) and less-common vertebrate models

What can vertebrate models tell us and what not?

* 4) The phylotype

Comparison of embryonic development within animal kingdoms.

Funnel model of embryonic development (eggs are similar, later developmental stages diverge).

The phylotype and hourglass model of embryonic development (middle developmental stages are similar, earlier and later stages diverge).

Alternative ideas (inverse hourglass, folded ribbon models).

Developmental evidence.

* 5) Stomy types

Stomy types and comparative embryology at the level of Protostomia and Deuterostomia.

Gastrulation and stomy types – protostomy/deuterostomy/amphistomy vs. Protostomia/Deuterostomia.

Protostomia does not equal protostomy – diversity of stomy types (causa Chaetognatha, Priapulida and Brachiopoda).

Mouth equals anus vs. mouth does not equal anus. Homologies of body openings?

Blastoporus as an indicator of the main body axis? Body axes inversion at the base of chordates.

* 6) Comparative embryology of an eye

Types of eyes – from a single cell to complex organs (division of labor model)

The same genes in the development of diverse eyes – example of Pax6 in Drosophila and vertebrates.

Pax6 and multiple origin of eyes.

Various genes in the development of similar structure – crystallines and the lens.

Camera-type eyes in vertebrates and their origin (irreducible complexity)

* 7) The problem of body segmentation

Segmentation and positional identity vs. segmentation and the „clock and wavefront“ model.

Segmentation in annelids, arthropods and chordates.

Types of segmentation in chordates.

Potentially shared characters of individual segmentation types.

* 8) Integration of new cell types and the vertebrate head

Comparative embryology of chordates – neural crest, placodes and the new head.

Neurulation in chordates and specification of tissues.

Placodes and neural crest in vertebrates.

Urochordates and development of placodes and neural crest?

Cephalochordates and development of placodes and neural crest?

Integration of structures and the origin of the new head in vertebrates.

* 9) Development of iterative structures and the origin of patterns

Development of integumentary derivatives (hair, feathers, scales).

Regulation of distribution of skin derivatives, activator zone, inhibitory zone.

What does regulate regular distribution? Why aren’t individual organs fused? Can new organs be added?

Positional information (French flag model) vs. Turing patterns.

* 10) Modelling in embryonic development

Why to model?

Types of modelling (biomechanics, cellular automaton, oscillators, reaction-diffusion processes, agent-based models).

Process vs. pattern.

Homology of processes vs. structural homology.

* 11) Body coloration

Body surface types and coloration in invertebrates and vertebrates.

Dermal layers and position of pigment cells.

Production of color patterns.

Evolutionary origin of coloration.