Question

identify the function and/or fate during development of each of the following

            Notochord                               neural tube                  somites                        infundibulum

            Metanephric mesenchyme      ureteric bud                 mesonephrous             Rathke’s pouch

            Neural crest cells                    trophoblast                  inner cell mass                        amnion

            Chorion                                   yolk sac                       allantois                      archenteron

            Henson’s node                        primitive streak           optic cup                     Wolffian duct

            Mullerian duct                        pronephric duct           LH                               FSH

            Progesterone                           HCG    

Answer 1

a.Notochord - flexible,rod shaped body found in embryos of all chordates,derived from mesoderm.It serves as the basis of the axial skeleton.

b.Metanephric mesenchyme - involved in the formation of kidney,it is one of the two embryonic structures that leads to the formation of kidney,the other one is ureteric bud.Metanephric mesenchyme consists of mesenchymal cells and these cells later forms the neurons,and are located adjacent to the tips of the branching ureteric bud.

c.Neural crest cells - Majour source of connective tissue componenets including cartilage,bone,ligaments of facial and oral region.(thereby contributes to the formation of muscles and arteries of this region).They are of ectomesenchymal in nature.

d.Chorion - consists of hypocellular ,densely collagenous stroma containing large muscularized fetal chorionic vessels and involved in the formation of major tributaries of umbilical vessels.

e.Henson's node - also known as the primitive knot,found in birds ,reptiles and mammals.Functional equivalent of the dorsal lip of the blastophore in amphibians.Appears as regional thickening of cells at the top or anterior,of the primitive groove through which gastrulating cells migrate anteriorally to form tissues in the future head and neck.

f.Mullerian duct - primordial basis of the female reproductive tract,differerntiates and forms the fallopian tube,uterus and uterine cervis as well as the superior aspect of the vagina.

g.Progesterone - synthesized and secreted by corpus luteum and placenta.Acts as an intermediate in the formation of steroid hormones from cholestrol.

h.Neural tube - embryonic structure that ultimately forms the brain and spinal cord.

i.Ureteric bud - divides and branches forming the renal pelvis ,infundibulae,collecting tubules and calyces- parts that play important role in the conduit of urine drainage in kidney.

j.Trophoblast - important role in embryo implantation and interaction with the endometrium of the maternal uterus during decidualization.

k.Yolk sac - important role in the early nutrition of the embryo and the early source of haematopoiesis.