Developmental Biology (Bio 445)

Lecture Guide

(pages 63-71 Moore)

 

NOTE: We will also cover some material in Wolpert, Chap 8 (up to Neurulation).  We may not get into this at all until Wednesday.  But please preview that chapter also.

 

Third week of Development.

 

__________________ is the process by which the ____________________ embryonic disc  is converted into the _________________________________.

 

Gastrulation is the beginning of ______________________________________.

 

During this period, the embryo is referred to as a _____________________. 

 

_____ important processes occur during this period.

 

1.     ________________________________

2.     ________________________________

3.     ________________________________

 

Primitive Streak

 

- This structure appears as _________________________ of the embryo. 

 

- It is formed by ______________________ and ______________________ of ___________________________cells to the ___________________ plane of the embryonic disc.

 

The primitive streak _________________________caudally.

 

_______________________ – forms at the caudal end of the primitive streak.

 

The ________________________ forms  within the primitive streak and is continuous with a small depression , the __________________________. 

 

The formation of the primitive streak define the embryos _________________ ________________________ axis. 

 

 

 

Cells on the deep surface of the primitive streak form a __________________________________________________________ called ____________________________________ or mesoblast.  These cells form a layer known as the _______________________________________________.

 

 

______________________ – epiblast cells which have displaced the hypoblast.

 

_____________________ - formed from the remaining cells of the epiblast.

 

Cells from the ______________________ give rise to all three germ layers in the embryo.

 

The primitive streak normally degenerates by ___________________________ .

 

 

NOTOCHORD

 

The notochord:

1.     defines the ___________________________ and gives it some rigidity.

2.     serves as the basis for development of the _________________ ______________________ (bones of the head and vertebral column)

3.     indicates the future site of the ______________________________ .

 

___________________________ - formed from the cranial migration of ____________________ from the primitive _______________________ which forms a cellular cord.  This grows cranially between the __________________ and _____________________________ until it reaches the _______________ ____________________.

 

____________________________ - the lumen within the notochordal process. 

 

The prechordal plate halts the advancement of the notochordal process because its firmly attached to the _________________________ to form the _______________________________________________ (future site of the mouth).

 

_____________________ - future site of the _______________.  The germ layers are also fused here.  This prevents ___________________________ from migrating beyond this point.

 

The notochord is the primary inductor in the early embryo. 

 

The notochord induces the overlying ectoderm to thicken and form the _______________________________________.

 

 

Remnants of the notochord can be seen as the ___________________________ of each intervertebral disc.

 

The _________________ is a small diverticulum from the caudal wall of the _____________________________ projecting into the connecting stalk.  Its function is less critical in humans than in reptiles in birds.  However, is does play a role in the ___________________ and development of the __________________________ . 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1.

 

 

 

Figure 2.

 

 

 

Figure 3

 

 

 

 

 

 

Figure 4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 5