To review:
The fate of blastocyst in the embryos of monotreme mammals (e.g. platypus) and marsupial mammals (e.g. kangaroo) that lay eggs and have extremely short pregnancies respectively.
Introduction:
The blastocyst is defined as a structure which is formed during the early developmental stage of mammals. It is mainly characterized by the presence of an inner cell mass (ICM) which is responsible for the formation of embryo. The outer layer of blastocyst is known as trophoblast. Unlike eutherian mammals, marsupials have short pregnencies, and are born very early in embryonic development. In oviparous monotremes, the offsprings also raised in maternal pouch. Deposition of the egg from the cloaca takes place directly for the incubation.
Explanation of Solution
The blastocyst is responsible to carry the embryo from cleavage to gastrulation. This structure bears a remarkable diversity in its mode of formation, longevity, morphology and association with uterine endometrium in different organisms. In terms of evolution of viviparity, the principal drivers of blastocyst evolution is associated with loss of yolk coupled with evolution of the placenta. In many species the trophoblast segregation is associated with blastocyst formation, but in case of marsupials these processes not coincide. In monotremes and most of the marsupials the zygote undergo polarization. The clevage signal are related to this polarized state. The embryonic-cell lineages are developed at the center of the blastocyst epithelium and extra embryonic lineages are developed at the periphery.
There are a number of similarities and differences are present in eutherians and other mammals like marsupials and monotremes. In marsupials and monotremes, the pluriblast or the inner cell mass is not enveloped by the trophoblast. Here the ICM is part of a continuous epithelium that forms the unilaminar blastocyst, and this pluriblast than segregates into hypoblast and epiblast.
Thus it is concluded that unlike eutherian, marsupials and monotremes bears the inner cell mass, not enveloped by the trophoblast, which later forms the hypoblast and epiblast which give rise to different germ layers.
Want to see more full solutions like this?
Chapter 12 Solutions
Developmental Biology
- [questions 4-6] Volume of the sea Urchin egg is 5.2 x 105 µm3 . You fertilize the cells and take measurements of cellular dimensions at the four blastomere stage. Assume a perfect sphere 4) What is the radius of the sea urchin egg? A) 500 µm B) 100 µm C) 49.9 µm D) 25 mm E) 25 µm F) 6 metersarrow_forwardNeed help 1 and 2 1.) Which of the following change occurs during the third trimester of fetal development? A. Skin appears bright pink due to blood-filled capillaries B. Lanugo hair develops C. Bone development begins D. All red bood cells are formed in the bone marrow 2.) Hormones play an important role in controlling the development and general metabolism of the human body Hormones are secreted by ductless glands called endocrine glandsFrom the following endocrine glands choose the one that develops from the ectoderm : A. Adrenal cortex B. Parathyroid gland C. Pituitary gland D. Thyroid glandarrow_forwardIDENTIFICATION (Subject - Development Biology) 1. It is a historical transformation of the forms of life starting from the simple forms of the past to the complex forms of the present? 2. This is formed when small group of cells segregate from another group of cells? 3. Its a process when one embryonic region interacts with the second and affects the second regions differentiation or behaviour?arrow_forward
- NEED ASAP THANKS A 25-year-old G1P0 seeks consult at a Maternity Clinic. A non-stress test was requested by the attending physician. During the procedure, the tracing displays a relatively flat line for fetal movement, making it difficult to evaluate the fetal heart rate (FHR). To mark the strip, the nurse in charge should instruct the client to push the control button at which time? a. At the end of fetal movement b. At the beginning of each contraction c. At the beginning of each fetal movement d. After every three fetal movementsarrow_forwardQuestion:- There are specific critical periods during fetal development in which any damage caused to the fetus from malnutrition or exposure to toxins is irreversible. When do these periods occur? a) 3rd trimester b) 1st trimester c) 2nd trimester d) only at week 12 e) there are no critical periodsarrow_forwardTOPIC 2 OBJECTIVES • How do physical laws affect morphology? • What is meant by the term “efficiency”? • How can I make sure I’m using it correctly? • How does the size of an organism constrain its morphology? • How can we use physics to describe the function of vertebrate limbs? • How do vertebrates address the problems of movement through fluids? • How do we describe the strength of vertebrate tissues? • How do vertebrate tissues respond to stress? • How do physical constraints control the movement of materials between organisms and the environment?arrow_forward
- Need help with question 1 and 2. 1.) Teratogens are agents that interfere with the normal growth of the fetus and induce abnormalities in them due to exposure during pregnancy. Teratogenic agents include various maternal health factors such as diabetes, physical agents such as ionizing agents, prescription drugs or over-the-counter medication, environmental chemicals such as mercury compounds, and many other recreational factors such as cigarettes and alcohol. Drugs and recreational factors such as cigarettes and alcohol are the main causes of fetal abnormalities. Many drugs cross the placenta by simple diffusion, and reach the fetus from the mother. The most common teratogenic effects of drugs are spontaneous abortions and congenital malformations. Some drugs, such as warfarin, phenytoin and thalidomide are known to have teratogenic effects. Thalidomide was a drug prescribed by doctors in the 1950s to reduce morning sickness, but after its deadly effects were recognized it was…arrow_forwardQuestion nursing. Oint When doctors discuss prenatal development, they often calculate the due date from the first day of menstruation. In fact, the baby’s gestational age is calculated from the first day of menstruation. At a maternity clinic, an obstetrician mentions that when a woman is 10 weeks pregnant, the baby is referred to as a fetus.Which of the following is the correct calculation of the baby’s age from the moment of fertilization, assuming a 28-day ovarian cycle? a. The baby is 8 weeks old. This is when organ formation has completed. b. The baby is 10 weeks old as stated by the doctor..arrow_forwardQuestions for Part 2 for Ken Burns The Gene: An Intimate History "Revolution in the Treatment of Disease" What was the Human Genome Project? When was it and give results. What inherit dangers go along with genetic engineering? What is genome sequencing? What makes viruses unique for genetic engineering? What happened with the first Gene Therapy Trials for OTC at the University of Pennsylvania? Why did it fail specifically? Describe Sickle Cell Disease and on what gene does the mutation reside? Explain the significance of the companion gene and the gene for sickle cell in gene therapy? What is CRISPR and how is it used? please answer 4,5,6 please asap.arrow_forward
- Questions for Part 2 for Ken Burns The Gene: An Intimate History "Revolution in the Treatment of Disease" What was the Human Genome Project? When was it and give results. What inherit dangers go along with genetic engineering? What is genome sequencing? What makes viruses unique for genetic engineering? What happened with the first Gene Therapy Trials for OTC at the University of Pennsylvania? Why did it fail specifically? Describe Sickle Cell Disease and on what gene does the mutation reside? Explain the significance of the companion gene and the gene for sickle cell in gene therapy? What is CRISPR and how is it used? pleaae answer 1,2,3 asaparrow_forwardIDENTIFICATION (Subject - Development Biology) 1. It refers to the arrangement of the mitochondria, golgi apparatus, yolk and pigment granules? 2. It shows the organ forming tissues? 3. It is a genes which are active all throughout developmentarrow_forwardneed help with Q4-Q5 Thanks!arrow_forward
- Understanding Nutrition (MindTap Course List)Health & NutritionISBN:9781337392693Author:Eleanor Noss Whitney, Sharon Rady RolfesPublisher:Cengage LearningCase Studies In Health Information ManagementBiologyISBN:9781337676908Author:SCHNERINGPublisher:Cengage