EMBRYOLOGY: EARLY EMBRYO This picture shows the three (3) phases of fertilization

. Identify the three phases. . What is capacitation? What does the process of capacitation involve? . What is acrosome reaction? The picture shows the oocyte completing its second meiotic division in preparation for fertilization

. The nucleus of the oocyte will form a female pronucleus while the sperm nucleus will form the male proncleus. . What will the two pronuclei form? The above pictures show the formation of the morula from a two- celled zygote.

. What is the name of the process by which the zygote divides? . What are the cells resulting from this division called? The picture shows the differentiation of the inner cell mass cells into the epiblast and hypoblast layers

. The outer cell mass cells have differentiated into the inner cytotrophoblast and an outer syncytiotrophoblast. . What is the significance of the syncytiotrophoblast layer? The picture shows the formation of the blastocyst cavity and the implantation of the blastocyst

. What results in the formation of the blastocyst cavity? . By implanting, what type of nutrition is the embryo seeking? The picture shows the formation of lacunae in the syntrophoblast layer as well as the formation of the exocoelomic membrane

. What is the significance of this layer? . What is found within the amniotic cavity? The picture shows the formation of the extra-embryonic mesoderm

. What is the significance of this layer? . What stage of development is depicted on this picture? The picture shows the flow of blood maternal into the lacunae

. What causes the maternal blood to flow into these lacunae? . What is the significance of this utero-placenta circulation? . What is an exocoelomic cyst? This picture shows the process of gastrulation (primitive streak formation) in the embryo

. What is the name given to the new layer that is going to be formed? This picture shows the dorsal view of the embryo in the third week of development

. What results in the formation of the primitive streak? . On what day does the primitive streak form? This picture shows the dorsal view of the embryo in the third week of development

. What will the notochordal process form? The picture shows the process of neurulation

. Which structure induces the formation of the neural tube? . What will the neural tube form in the adult? The picture shows the condensation of intraembryonic mesoderm into the paraxial, intermediate and lateral plate mesoderm

. Which structure induces the condensation of this mesoderm? The picture shows the arrangement of the three germ layers in the embryo

. What are the derivatives of the neural tube, notochord, intermediate and lateral plate mesoderm? Short essay questions

. Describe the embryonic formation of the morula. (6 marks)

. Describe the process of neurulation. (8 marks)

. Draw a schematic diagram showing the arrangement of the intra-embryonic mesoderm following induction by the notochord. (6 marks)

Multiple choice questions

. The intraembryonic coelom forms

a) The secondary yolk sac. b) The exocoelomic cavity. c) The amniotic cavity. d) The pericardial cavity. e) The extraembryonic coelom.

. The main results of fertilization are

a) Initiation of cleavage. b) Formation of the neural tube. c) Determination of a sex of an individual. d) Restoration of the diploid number of chromosomes. e) Formation of a blastocyst cavity.