INTERMEDIATE AND LATERAL MESODERM

intermediate mesoderm

forms the urogenital system, consisting of the kidneys, the gonads, and their associated ducts outer (cortical) portion of the adrenal gland

kidney

bean-shaped organ found at the o back of the abdominal cavity

filtration
reabsorption
secretion

kidney

nephron

functional unit of kidney (10,000 cells and at least 12 different cells)

pronephros

HOW THE INTERMEDIATE MESODERM BECOMES KIDNEY-FORMING TISSUE

Signals from the paraxial mesoderm induce __________ formation in the intermediate mesoderm of the chick embryo.

pronephric kidney

The paraxial mesoderm was surgically separated from the intermediate mesoderm on the right side of the body. As a result, a ___________ developed only on the left side.

pronephros
mesonephros
metanephros

STRUCTURE OF A KIDNEY

pronephros

Forms from intermediate mesoderm ventral to anterior somites.

Pronephric duct

migrates caudally, inducing adjacent mesenchyme to form pronephric tubules

nephric duct

pronephros Degenerates in mammals; remnants form the Wolffian/ ________

mesonephros

Induced by the middle portion of the Wolffian duct

pronephros
mesanephros

transient structures of a kidney

metanephros

permanent structure of a kidney

Posterior intermediate mesoderm

origin of metanephros

metanephric mesenchyme
ureteric buds

2 Distinct Progenitor Cell Populations of metanephros

Metanephric Mesenchyme

Committed kidney-forming tissue.

Ureteric Buds

Epithelial branches from Wolffian duct → form collecting ducts, ureters, and bladder connection.

ureteric bud

. shorter Wnt exposure ⟶

metanephric mesenchyme

longer Wnt exposure ⟶

GDNF

The metanephric mesenchyme secrete ______ to induce and direct the ureteric bud

Retinoic acid

GDNF binds to ________ receptor on the nephric duct, causing the ureteric bud to grow out, forming the collecting duct system

FGF2
BMP7

The ureteric bud secretes

Wnt9b
Wnt6

_____ and ______ from the ureteric bud signal the mesenchyme to become nephron-forming epithelial cells.

Wnt4

mesenchyme produces ______ in response, finalizing transformation nephron ⟶C-shaped and S-shaped tubules

lateral mesoderm

gives rise to the heart, blood vessels, and blood cells of the circulatory system, and the lining of the body cavities gives rise to the pelvic and limb skeleton

Heart Field Formation

Tunicate Embryos vs Vertebral Heart Formation

Heart Progenitor Cells

Primitive Steak

Cardiogenic Mesoderm

Linear Heart Tube

heart progenitor cells

originate near the rostral primitive streak in the gastrula.

primitive streak

heart progenitor cells Migrate through the _________ to form lateral plate mesoderm groups.

first heart field

Forms the primary heart tube scaffold

second heart field

Role: Adds cells to anterior/posterior ends of the heart tube.

C-looping

involves the transformation of the initially straight heart tube into a C-shape

S-looping

further transforms this C-shape into the mature S-shaped loop

Cardiomyocytes
Endocardium
Endocardial cushions
Epicardium

CELL TYPES OF THE HEART

1. _______ that form the muscular layers

2. ________ that forms the internal layer

3. ________ of the valves

4. _________ that forms the coronary blood vessels

that feed the heart

5. Purkinje fibers that coordinate the heartbeat

vasculogenesis

The initial formation of blood vessels

hemangioblasts

Give rise to hematopoietic (blood cells) and endothelial (blood vessels)

Runx1 transcription factor

induces the conversion of endothelial cells to blood stem cells

angiogenesis

Sprouting of blood vessels and remodeling of vascular beds