Talk:Week 6

From Embryology

Timeline

Day
Stage
Event
36
Pituitary Week 6 - connecting stalk between pouch and oral cavity degenerates

Parathyroid Week 6 - diverticulum elongate, hollow then solid, dorsal cell proliferation

Thymus Week 6 - diverticulum elongate, hollow then solid, ventral cell proliferation

Adrenal Week 6 - fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia

Respire Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes

Tongue Week 6 - gustatory papilla, caudal midline near the foramen caecum (week 6 to 7 - nerve fibers approach the lingual epithelium)

37
Stage 16 Stage16 bf1c.jpg Neural first parasympathetic ganglia, submandibular and ciliary, are identifiable[1]

Limbs upper limb bud nerves median nerve, radial nerve and ulnar nerve entered into hand plate, myoblasts spindle shaped and oriented parallel to limb bud axis.

Heart outflow tract elliptical configuration with four cushions, the two larger fusing at this stage. Semilunar valve leaflets form at the downstream end of the cushions

Head lip and palate components of the upper lip, medial nasal prominence and maxillary process present, median palatine process appears.

38
   
39
   
40
   
41
Stage 17 Stage17 bf1c.jpg

Neural telencephalon areas of the future archicortex, paleocortex, and neocortex, visible. Beginning of future choroid plexus[2]

Sense - Smell olfactory nerve fibres enter the brain[3] Neural primordium of the epidural space appears first on the ventral part of the vertebral canal and develops rostro-caudally[4]

42
  Heart separation of common cardiac outflow (aortic arch and pulmonary aorta)

References

  1. F Müller, R O'Rahilly The human brain at stage 16, including the initial evagination of the neurohypophysis. Anat. Embryol.: 1989, 179(6);551-69 PubMed 2751117
  2. F Müller, R O'Rahilly The human brain at stage 17, including the appearance of the future olfactory bulb and the first amygdaloid nuclei. Anat. Embryol.: 1989, 180(4);353-69 PubMed 2802187
  3. F Müller, R O'Rahilly Olfactory structures in staged human embryos. Cells Tissues Organs (Print): 2004, 178(2);93-116 PubMed 15604533
  4. Magdalena Patelska-Banaszewska, Witold Woźniak The development of the epidural space in human embryos. Folia Morphol. (Warsz): 2004, 63(3);273-9 PubMed 15478101