To review:
The need for the two different mechanism for the formation of neural tube in relation to the evolutionary pressures that forced the adoption of secondary neurulation. The idea which influence the timing of end of gastrulation and its capacity for axis elongation in relation to neurulation.
Introduction:
The set of morphogenetic events that leads to the formation of neural tube is known as neurulation. This process acts as a base for the formation of central nervous system in different organism. Neurulation is characterized as a complex set of cell movements which includes epithelial columnarization, migration, intercalation and convergent extension. Multiple genes are involvesd in regulation of this process. Neurulation is accompained by two modes, primary neurulation and secondary neurulation.
Explanation of Solution
The formation of vertebral neural tube into anterior and posterior tube are two independent processes specific in morphogenetic and molecular processes. The anterior tube forms by primary neurulation, in contrast posterior tube forms via secondary neurulation. The main difference between these two processes is the role of epithelial and mesenchymal cell population. Epithelial tissues are an organized and continuous sheet of cells associated by junctional complexes whereas the mesenchymal tissue are loosely connected cells.
The evolutionary studies indicate that the mechanism of primary neurulation was the ancestral condition and the secondary neuraltion is evolved later like the evolution of limbs. Before the formation of neural tube, primary neurulation uses a flat neural plat whereas the secondary neurulation starts with a mesenchymal cell population which later condensed. The comparision of early stages serve to evaluate the evolutionary conservation. The precise movement in different vertebrates, shows a number of solutions to the problem of change in neural plate cells into a neural tube. So the morphological and antamoical changes with due course of time may be a reason for the evolution of secondary neurulation. The neural induction, at any given time during gastrulation is regulated by the different cells at the organizer and under the control of precise gene regulation. The cell division in the neural plate is preferentially in anterior-posterior direction, which also regulates the axis elongation during gastrulation.
Thus it is concluded that primary neurulation was the ancestral condition and the secondary neuraltion is evolved later like the evolution of limbs. The comparision of early stages serve to evaluate the evolutionary conservation. The precise movement in different vertebra may be a reason for this evolutionary condition.
Want to see more full solutions like this?
Chapter 13 Solutions
Developmental Biology
- Question: Regarding the events that take place in the complex process of spermatogenesis, which of the following statements is true: a.The sperm nucleus behaves like that of any other somatic cell, and remains quiescent until its replication during cell division, maintaining the RNAs. b.RNA transcription is continuous, and even increases as the process progresses, since the RNA content in the sperm will have a key relevance in early embryo development and is related to assisted reproduction outcomes. c.RNA transcription in the sperm does not contribute to embryo quality or reproductive success, since it is silenced, and the oocyte will be responsible for its contribution as well as its functionalities in the embryo. d.There is no RNA transcription in the later stages, but the mRNA content in the sperm that comes from previous stages of spermatogenesis will have a key relevance in early embryo development and has been related to the ability of the sperm to achieve a pregnancy.arrow_forwardSubject [Developmental Biology] Question; In an OUTLINE FORM, describe briefly the phases of neurulation. Mention some signaling molecules, genes, morphogenetic factors, and other factors, intrinsic/extrinsic factors responsible for each phase. NOTE [Follow the instruction]arrow_forwardHelp please? The Topic is sexual reproduction and its physiology. Scenario: During the ovarian cycle, estrogen secretion by the dominant follicle eventually gets so high that it triggers the hypothalamus to produce and secrete even more gonadotropin-releasing hormone (GnRH). This release of GnRH into the anterior pituitary typically causes the anterior pituitary to release a large amount of luteinizing hormone and a much smaller amount of follicle-stimulating hormone. However, Tiffany K. produces a ton of follicle-stimulating hormone and luteinizing hormone during the end of her follicular phase. She had a bad experience with medical doctors in the past, and so she her medical doctor to figure out what is going on. She asks you if you had any suggestions about what hormone the doctor should test first. You tell Tiffany it would make sense for the doctors to first check her levels of...(see image)arrow_forward
- The 48-hr Chick Embryo Whole Mount (SEE IMAGE) Before you mount your slide on your microscope stage, take a good look at the morphology of the 48-hour embryo. Note the striking changes in morphology as compare, to the 33-hour embryo. There is a cephalic flexure or bending at the level of the midbrain. The head now lies on its left side. On the other hand dorsal side of the trunk is still turned up so the twisting of the embryo is noticeable. Verify these changes under the low power objective. Note the flexion and the torsion. In addition to the cranial/cephalic flexure there is also a cervical flexure at the level of the neck region. Very briefly go through the structures previously seen in the 33-hour chick. Observe the new structures appearing for the first time (Please visit the main website for viewing the whole mount of 33-hour and 48-hour chick embryo). Ectodermal Derivatives The prosencephalon is now divided into two regions: Telencephalon: This brain region is the anterior…arrow_forwardThe 48-hr Chick Embryo Whole Mount (SEE IMAGE) Before you mount your slide on your microscope stage, take a good look at the morphology of the 48-hour embryo. Note the striking changes in morphology as compare, to the 33-hour embryo. There is a cephalic flexure or bending at the level of the midbrain. The head now lies on its left side. On the other hand dorsal side of the trunk is still turned up so the twisting of the embryo is noticeable. Verify these changes under the low power objective. Note the flexion and the torsion. In addition to the cranial/cephalic flexure there is also a cervical flexure at the level of the neck region. Very briefly go through the structures previously seen in the 33-hour chick. Observe the new structures appearing for the first time (Please visit the main website for viewing the whole mount of 33-hour and 48-hour chick embryo). Ectodermal Derivatives The prosencephalon is now divided into two regions: Telencephalon: This brain region is the anterior…arrow_forwardThe 48-hr Chick Embryo Whole Mount (SEE IMAGE) Before you mount your slide on your microscope stage, take a good look at the morphology of the 48-hour embryo. Note the striking changes in morphology as compare, to the 33-hour embryo. There is a cephalic flexure or bending at the level of the midbrain. The head now lies on its left side. On the other hand dorsal side of the trunk is still turned up so the twisting of the embryo is noticeable. Verify these changes under the low power objective. Note the flexion and the torsion. In addition to the cranial/cephalic flexure there is also a cervical flexure at the level of the neck region. Very briefly go through the structures previously seen in the 33-hour chick. Observe the new structures appearing for the first time (Please visit the main website for viewing the whole mount of 33-hour and 48-hour chick embryo). Ectodermal Derivatives The prosencephalon is now divided into two regions: Telencephalon: This brain region is the anterior…arrow_forward
- The 48-hr Chick Embryo Whole Mount (SEE IMAGE) Before you mount your slide on your microscope stage, take a good look at the morphology of the 48-hour embryo. Note the striking changes in morphology as compare, to the 33-hour embryo. There is a cephalic flexure or bending at the level of the midbrain. The head now lies on its left side. On the other hand dorsal side of the trunk is still turned up so the twisting of the embryo is noticeable. Verify these changes under the low power objective. Note the flexion and the torsion. In addition to the cranial/cephalic flexure there is also a cervical flexure at the level of the neck region. Very briefly go through the structures previously seen in the 33-hour chick. Observe the new structures appearing for the first time (Please visit the main website for viewing the whole mount of 33-hour and 48-hour chick embryo). Ectodermal Derivatives The prosencephalon is now divided into two regions: Telencephalon: This brain region is the anterior…arrow_forwardQ3/ Q1/ what kind of division can perform normal growth and development for the ?embryo & whyarrow_forward+Describe the process of implantation of the embryo, what cells are involved and their roles. +Describe placentationarrow_forward
- Question:- Gonadotropin-releasing hormone (GRH) is a hormone from the hypothalamus responsible for the release of the tropic sexual hormones FSH and LH (whose peak induces ovulation) from the anterior pituitary that act on the ovary. Explain why it is advantageous to have the brain (rather than a typical negative feedback) control the dynamic secretion of GnRH over the 28-day period of the estrus cycle. Imagine when GnRH is produced.arrow_forward33-hour Chick Embryo Whole Mount, At what level of the neural tube do you find the anteriormost somite?arrow_forwardLearning Task 6: Essay .Explain why there is a high level of estrogen and progesterone once in every 28-day uterine cycle of a female, Refer your answer on Fig.2 Negative Feedback Mechanisms in Menstrual cycię, Day 4: Nervous System Working Together with Endocrine System to Maintain Homeostasis Learning Task 7: Read and answer the given questions after the lesson. Homeostasis is the state reached when each part of the body functions in equilibrium with other parts. This is attained through the regulation of the bodily functions by the endocrine and nervous systems. Most body system maintain homeostasis by using feedback mechanisms. When the brain reçeives messages from the body about an internal change in one of its systems, it works to restore the system to its normal state. The levels of hormones in the body are controlled by feedback. It is important that the amount of homeostasis in our body is kept at the right level. To achieve homeostasis, the nervous and endocrine systems…arrow_forward
- Understanding Nutrition (MindTap Course List)Health & NutritionISBN:9781337392693Author:Eleanor Noss Whitney, Sharon Rady RolfesPublisher:Cengage LearningBiology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage LearningAnatomy & PhysiologyBiologyISBN:9781938168130Author:Kelly A. Young, James A. Wise, Peter DeSaix, Dean H. Kruse, Brandon Poe, Eddie Johnson, Jody E. Johnson, Oksana Korol, J. Gordon Betts, Mark WomblePublisher:OpenStax College