In case of hotstart PCR, After the reaction mixture is prepared, primers can pair to the single-stranded regions in a nonspecific manner. 

A more attractive alternative is to cover the reaction mixture with a plug of inert wax and place the critical reagent on top of this plug. 

TLS Online TPP Program

#Id: 1039

#Unit 5. Developmental Biology

Craniorachischisis-combination of anencephaly with a contiguous bony defect of the spine (also without meninges covering the neural tissue –rachischisis)

TLS Online TPP Program

#Id: 1040

#Unit 5. Developmental Biology

The first visible sign of limb development is the formation of bilateral bulges called limb buds.

1. limb bud  is 

TLS Online TPP Program

#Id: 1041

#Unit 5. Developmental Biology

The cells that make up the limb bud are derived from the 

1. posterior lateral plate mesoderm

2. adjacent somites

3. bud’s overlying ectoderm

TLS Online TPP Program

#Id: 1042

#Unit 5. Developmental Biology

Limb field - All the cells are capable of forming a limb on their own.

TLS Online TPP Program

#Id: 1043

#Unit 5. Developmental Biology

The positional information needed to construct a limb has to function in a three-dimensional coordinate system:

Proximal-distal axis

Anterior-posterior axis

Dorsal-ventral axis

TLS Online TPP Program

#Id: 1044

#Unit 5. Developmental Biology

The limb bud is regionalized into 3 functional domains

1. Progress zone

2. Zone of polarizing activity

3. Apical ectodermal ridge