Mouse Embryo Skeletal Staining (Part 2)

The mouse embryo skeletal prep below was stained with Alcian Blue (for cartilage) and Alizarin Red (for bone). See my previous post Mouse Embryo Skeletal Staining (Part 1) for reference to the protocol. 

The skeletal prep came out too dark for my preference.  Next time, I will greatly restricting the amount of time in Alcian Blue and a prolonged destaining. Alternatively, staining for just bone with Alizarin Red will also provide a nice visualization of where calcium is binding.

Mouse embryo skull and vertebrae (dorsal view)

I shone a light through the front of the skull. You can see the bottom of occipit from the inside illuminated. In the foreground, you can see the first cervical vertebrae (atlas or C1). It is quite larger than the others.

Mouse embryo occipit, illuminated from inside (dorsal view)

Note that the middle of each prospective vertebrae is cartilage and has not ossified. I assume that in this area, the future neural arch will begin to protrude, as seen in adults.
 

Mouse embryo spine, scapula and and vertebrae, including the C1 atlas and C2 axis vertebrae (dorsal view).

Thoracic vertebrae in a mouse embryo (dorsal view)

I disarticulated the arm below to give a view inside the thoracic cavity.

Thoracic shot of a  mouse embryo (left lateral view)

Mouse embryo's cervical and thoracic vertebrae (left lateral view)

The ribs articulate with the vertebrae (dorsally) and the costal cartilage in blue at the ventral side.

Mouse embryo's ribs, costal cartilage and vertebae (left lateral view)

I could see the cartilaginous tracheal rings extending downwards.

Trachea in a mouse embryo (left lateral view)

Odd cartilage protrusions extend laterally from the thoracic vertebrae and lumbar. These may be the future transverse processes.
 

Thoracic and lumbar vertebrae in the mouse embryo (right lateral view)

The more distal vertebrae (caudal vertebrae) progressively look more like amorphous cartilage condensations and appear to ossify at a later stage than the more proximal vertebrae.

Caudal pre-vertebral condensations in the mouse embryo (right lateral view)

Below are the thoracic and lumbar vertebrae. I shone the light through the anterior vertebral column, illuminating the center.

Thoracic and lumbar vertebrae of a mouse embryo (dorsal-superior view)

Lumbar vertebrae, os coxae (hip bones) and femurs of a mouse embryo (dorsal view)

It appears that the obturator foramen is still composed of some cartilage. I believe that the superior portion of the ischium and the pubis, which create the obturator foramen, are beginning to ossify, while the inferior portion of the ischium and pubis is still composed of cartilage.

Developing pelvic girdle of a mouse embryo (right lateral view)

Below is the mouse embryo's hand. Note the fingertips are ossifying, as are the mid-metacarpals and the mid-proximal phalanges..

Mouse embryo hand (prone)

Forearm of a mouse embryo, and the distal humerus (prone)

Mouse embryo metacarpals and phalanges (superior view)

On the left is the scapula, which articulates with the head of humerus. The humerus has a protrusion with a cartilaginous bump. I believe this is the deltoid tuberosity. 

Mouse embryo jaw, neck and shoulder girdle (right lateral view)

 


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