Which of the following is an illustration of permissive interaction?   -When implanted in the newt embryo, the frog oral ectoderm can only differentiate into frog derivatives and will not differentiate into newt derivatives.   -Contact with the appropriate extracellular matrix is sufficient for cells to express differentiation-specific genes.   -An inducing signal from the optic vesicle is necessary for new gene expression in the lens ectoderm.

Which of the following is NOT true about the specification of the eye field? (Check all that apply)   During early gastrulation, Noggin promotes the expression of both ET and Otx2.   ET induces RX, which in turn blocks Otx2 and Pax6.   ET induces RX, which in turn induces Pax6 and blocks Otx2 within the eye field.   It starts with neural induction when the neural plate is induced within the ectoderm.   During late gastrulation, Otx2 blocks the inhibition of ET by Noggin.   ET induces RX, which in turn induces Otx2 and Pax6.   Pax6 is only required for the specification of the retina.   Pax6 initiates the expression of a network of transcription factors, some of which mutually activate one another.   During late gastrulation, the forebrain and hindbrain are specified.   During early gastrulation, Noggin indices Otx2 but blocks E

What critical developmental process/es are altered following retinoic acid-exposure, which may cause protrusion of the spinal cord through the vertebral arches? Select one or more: O A. Primary neurulation, where the neural plate creases inward until the edges come in contact and fuse. O B. Secondary neurulation, where the tube forms by hollowing out of the interior of a solid precursor. O C. Regulation of neural crest migration from the neural tube to generate segmental ganglia. O D. Abnormal somite formation affecting the development of muscles of the back.

Discuss the role adhesion proteins play in the formation of the neural system, neural crest cells, and epithelial of the back in the developing embryo – neurulation.

The red arrows in Figure 1 indicate a normal open epiphyseal plate (an open growth plate).   What tissue is it made of? What tissue will it be made of once it has closed (fused)? Which bone is the growth plate part of? Describe how this growth plate formed. Start with the cartilage model in the embryo and end with what can be seen in this xray.

Describe the dorsolateral and ventrolateral migration of trunk neural crest cells. Provide details as to the timing of the migration, pathways taken, eventual fate, and location of the neural crest cells that follow each pathway or portion of the pathways. Include a simple drawing that depicts both pathways .

At one time, if a farmer wanted to improve his or her cattle herd, he or she would have to buy an expensive bull from another farmer who had a herd proven to show desirable characteristics. Now, semen from bulls with desirable characteristics can be shipped all over the world to help farmers improve their herds. Use the Internet to learn more about the use of artificial insemination (AI) as a cattle-breeding option.    (a)  What are the primary advantages and disadvantages of using AI to breed cattle?   (b)  How popular is AI as a breeding method for the beef and dairy industry?

The insect testis is composed of individual units called ____ , whereas the insect ovary is composed of individual units called ovarioles. In the type of ovariole referred to as ____ , the upper region called the germarium contains oogonia and cells called____ , which connect to forming eggs by long ____ that carry maternal mRNA to the egg.

-4. In the diagram below, the stages of development in a frog embryo are NOT arranged in the correct order. In what order should they be placed to show the normal sequence of development in the embryo? What process is occurring in this diagram? B. D Dorsal lip of blastopore Dorsal lip of blastopore Dorsal lip of blastopore Dorsal lip blastopon

Early in the development of skin, ectoderm becomes A. periderm and mesoderm becomes mesenchyme  B. mesenchyme and endoderm becomes periderm  C. the vernix caseosa and mesoderm becomes the stratum basale  C. perichondrium and mesoderm becomes the vernix caseosa