This fetal pig snout contains excellent examples of fibroblasts.
Mesenchyme is an early form of connective tissue found in embryos. It is composed of mesenchymal cells and ground substance. Mesenchymal cells can differentiate into other cell types such as fibroblasts, fat, cartilage and bone.
Skin - a stratified squamous epithelium that covers the specimen. This fetal epithelium is very hydrated giving it an unusual, "fluffy" appearance.
Cartilage - the two large, oval structures near the midline with a lower cell density.
Bone - basophilic spicules often with cells on their surface..
Tooth - a protrusion of tissue that will develop into a tooth.
Fibroblasts are actively producing the extracellular matrix between these developing tissues. In this state, their cytoplasm is visible. These cells appear spindle-shaped (fusiform) with elongated nuclei.