Cover some representativeexamples

Start with neurulation

3 hr

7 hr

15 hr

15 hr

17 hr

19 hr

23 hr

http://www.youtube.com/watch?v=kceCuKDz7IA&NR=1

Primary neurulation

Secondary neurulation

http://www.youtube.com/watch?v=qisrNX3QjUg

http://www.youtube.com/watch?v=ddg2IznSuYEhttp://www.youtube.com/watch?v=dXpAbezdOho&feature=related

Chick vs. Frog

Figure 12.5(1) Neurulation in the Human Embryo

Figure 12.9 Early Human Brain Development

Figure 12.5(2) Neurulation in the Human Embryo

The six pituitary cell types of Rathke's pouch are the: Corticotropes, which produce proopiomelanocortin (POMC) and cleave it into adrenocorticotropic hormone (ACTH) needed for glucocorticoid synthesis in the adrenal gland Melanotropes, which produce POMC, but cleave it into melanocyte-stimulating hormone-α (for pigment formation, feeding regulation) Somatotropes, which produce growth hormone (for cell proliferation) Lactotropes, which make prolactin (for milk production, uterine contractions) Gonadotropes, which synthesize lutenizing hormone and follicle stimulating hormone (for gonad growth and development)

Lens induction: Signals the Lens Experiences

Lens induction: Signals the Lens Experiences

Terms (definitions) for Establishment of cells and tissues(here use lens cells as an example)

• Competence, wherein cells can become lens precursors if they are exposed to the appropriate combination of signals.

• Specification, wherein cells have received the appropriate signals to become lens precursors, but progression along the pathway to lens can still be repressed by other signals.

• Commmitment (determination), wherein lens precursors have entered a differentiation pathway, and will become lens even in the presence of inhibitory signals.

• Differentiation, wherein the lens cells leave the mitotic cycle and express those genes characteristic of their cell type.

Go to Meso

Present the following after ENDO

Figure 1.6 Fate Maps of Different Vertebrate Classes at the Early Gastrula Stage

Cover some representativeexamples

Two critical inductions:Formation of the primary organizerAction of the primary organizer

Neurulation is induced (By the ‘primary organizer)’

-1 .The primary organizer induces neurulation and axis formation

-2 .The primary organizer itself arises from a previous induction

-1. The primary organizer induces neurulation and axis formation -The dorsal lip of the blastopore contains the primary organizer

-1. The primary organizer induces neurulation and axis formation -The dorsal lip of the blastopore contains the primary organizer

-1. The primary organizer induces neurulation and axis formation -The dorsal lip of the blastopore contains the primary organizer

Figure 10.21(1) Organization of a Secondary Axis by Dorsal Blastopore Lip Tissue

-1. The primary organizer induces neurulation and axis formation

Figure 10.21(1) Organization of a Secondary Axis by Dorsal Blastopore Lip Tissue

-1. The primary organizer induces neurulation and axis formation

Amphibian

Amphibian

Source of primary organizer shown on fate map

-1. The primary organizer induces neurulation and axis formation

-The primary organizer induces neurulation and axis formation

-The primary organizer itself arises from a previous induction

OR . . . where does the ‘primary organizer’ come from?

-The primary organizer itself arises from a previous induction

-The primary organizer itself arises from a previous induction

Contains the Nieuwkoop center

Experiment at the 32-cell stage

-The primary organizer itself arises from a previous induction The primary organizer is induced by the Nieuwkoop center

(a tissue with an endodermal fate)

The primary organizer arises due to an induction from the Nieuwkoop centerHow does the Nieuwkoop center arise?

The primary organizer arises due to an induction from the Nieuwkoop centerHow does the Nieuwkoop center arise?

The primary organizer arises due to an induction from the Nieuwkoop centerHow does the Nieuwkoop center arise?

The primary organizer arises due to an induction from the Nieuwkoop centerHow does the Nieuwkoop center arise?

The primary organizer arises due to an induction from the Nieuwkoop centerHow does the Nieuwkoop center arise?

Figure 11.20(1) Induction of a New Embryo by Transplantation of Hensen’s Node

THE ORGANIZER IS IN THE HENSEN’S NODE

Mammal

Figure 11.7 Convergence and Extension in the Zebrafish Gastrula

Zebrafish

Figure 11.8 The Embryonic Shield as Organizer in the Fish Embryo

Zebrafish

Figure 1.6 Fate Maps of Different Vertebrate Classes at the Early Gastrula Stage

All have homologous organizers