embryonic period Flashcards
Anterior visceral endoderm
Hypoblast cells migrate to the future cranial end of the embryo
Cranial end establishment: occurs before gastrulation
Important for head formation: transcription factors, OTX2, LIM1, HESX1, secreted factor Cerberus. All are inhibitors of nodal (pro caudal factors) activity in the cranial end of the embryo
Primitive streak initiated by…
Nodal (TGFB family)
Caudal end establishment
The node in the dorsal region is the organizer. Maintain by…
Nodal & HNF-3B
Once the streak is formed…
BMP-four is secreted throughout the bilaminar disc
BMP4 and FGF
Ventralize the mesoderm to contribute to kidneys, blood, and boy wall mesoderm.
Goosecoid activates chord, nagging and follistatin which…
Inhibit BMP expression of the dorsal mesoderm in the cranial region.
Ventralization is inhibited in the dorsal mesoderm of the cranial end of the embryo.
Regulate head formation
Brachyury T
Gene regulates the dorsal mesoderm in the middle and caudal regions. It encodes a transcription factor that binds to a T box in the DNA. It is expressed in the node, notochordal precursor cells and notochord.
Ventralization is inhibited in the dorsal mesoderm of the middle and caudal regions of the embryo.
Hox-C
Important in craniocaudal axis
Derivatives of the three germ layers
Endoderm, mesoderm, ectoderm
Paraxial mesoderm
Muscles of the head
Striated skeletal muscle
Skeleton except cranium
Dermis of skin
Connective tissue
Intermediate Mesoderm
Urogenital system including gonads, ducts, and accessory glands
Lateral mesoderm
Connective tissue and muscle viscera
Serous membranes of pleura, pericardium, and peritoneum
Primordial heart
Blood and lymphatic cells
Spleen
Suprarenal (adrenal) cortex
Mesoderm (Head)
Cranium
Connective tissue of head
Ectoderm
Neuroecotoderm
Surface ectoderm
Surface ectoderm
Epidermis, hair, nails, cutaneous glands, and mammary glands
Anterior part of pituitary gland
Enamel of teeth
Internal Ear
Lens of the eye
Neuroectoderm
Neural Crest
Neural Tube
Neural Crest
Cranial and sensory ganglia and nerves
Medulla of suprarenal gland (adrenal medulla)
Pigment cells
Pharyngeal arch cartilages
Head mesenchyme and connective tissue (visceral skeleton of head, and neck)
Bulbar and coral ridges in heart
Parafollicular cells of thyroid gland
Meninges except dura mater
Endoderm
Epithelial parts of Trachea, Bronchi, Lungs, of gastrointestinal tract, liver, pancreas, urinary bladder, urachus, pharynx, thyroid gland, tympanic cavity, pharyngotympanic tube, tonsils, parathyroid glands
By the beginning of the 3rd week, the paraxial mesoderm begins to organize into segments called somitomeres
the paraxial mesoderm begins to organize into segments called somitomeres
First appears in the 20th day in the…
cephalic region, then cephalocaudally