Introduction to Embryology
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What is the primary study focus of embryology?

  • Development of an embryo (correct)
  • Adult human anatomy
  • Postnatal development
  • Genetics of adult organisms
  • The embryonic period lasts until birth.

    False

    What is the term used for the compact ball of 16 cells formed on Day 3 of development?

    Morula

    A substance that causes abnormality in physiological development is known as a _____ .

    <p>teratogen</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Zygote = Earliest stage of embryo; formed when sperm and egg fuse Morula = Compact ball of 16 cells Embryoblast = Inner cell mass, also known as pluriblast Teratogen = Substance causing developmental abnormalities</p> Signup and view all the answers

    During which period does significant physiological development occur?

    <p>Fetal period</p> Signup and view all the answers

    Approximately 3% of people are born with congenital anomalies that require medical attention.

    <p>True</p> Signup and view all the answers

    What is the term for the mass formation of cells before the zygote becomes a morula?

    <p>Blastocyst</p> Signup and view all the answers

    The total duration from zygote formation to birth is approximately _____ days.

    <p>266</p> Signup and view all the answers

    What major changes occur during spermiogenesis?

    <p>Transformation of round spermatids into mature spermatozoa</p> Signup and view all the answers

    The acrosome contains hydrolytic enzymes that aid in fertilization.

    <p>True</p> Signup and view all the answers

    What is the haploid number of chromosomes contained in the nucleus of a mature spermatozoon?

    <p>23</p> Signup and view all the answers

    The head of the sperm consists of a nucleus and an ______ which contains digestive enzymes.

    <p>acrosome</p> Signup and view all the answers

    Match the parts of mature spermatozoon with their functions:

    <p>Head = Contains genetic material and enzymes for fertilization Middle piece = Provides energy for locomotion Tail = Enables motility of the sperm Neck = Connects the head to the middle piece</p> Signup and view all the answers

    What is indicated by the presence of spermatozoa with cytoplasmic droplets in an ejaculate?

    <p>Secondary malformation and immaturity</p> Signup and view all the answers

    Which part of the digestive system is considered the hindgut?

    <p>Rectum</p> Signup and view all the answers

    Spermatogenesis occurs in the ovaries of females.

    <p>False</p> Signup and view all the answers

    What is the primary function of gametogenesis?

    <p>To produce gametes (sperm and egg cells)</p> Signup and view all the answers

    The mature female reproductive cell is known as a ______.

    <p>ovum</p> Signup and view all the answers

    Match the stages of oogenesis with their descriptions:

    <p>Oogonium = Immature cell developing into an ovum Primary oocyte = Ovum that undergoes meiosis but arrests in prophase I Tertiary follicle = Largest follicle containing a mature ovum Ovulation = Release of the mature ovum into the oviduct</p> Signup and view all the answers

    At what stage does oogenesis pause until further development occurs?

    <p>Primary oocyte</p> Signup and view all the answers

    Females produce a new ovum every month from puberty until menopause.

    <p>True</p> Signup and view all the answers

    Identify the male reproductive organ where spermatogenesis takes place.

    <p>Testes</p> Signup and view all the answers

    The proximal 2/3 of the transverse colon is part of the ______.

    <p>midgut</p> Signup and view all the answers

    How many eggs does a female typically develop in her lifetime?

    <p>400-500</p> Signup and view all the answers

    Which germ layer is responsible for forming the skin and nervous system?

    <p>Ectoderm</p> Signup and view all the answers

    The trophoblast is responsible for forming the inner layer of the blastocyst.

    <p>False</p> Signup and view all the answers

    What is the process called when the bilaminar germ disc acquires a third germ layer?

    <p>Gastrulation</p> Signup and view all the answers

    The _______ is formed by end of Week 2 from epiblast cells.

    <p>Amniotic cavity</p> Signup and view all the answers

    Match the following structures with their functions:

    <p>Yolk sac = Provides nutrients to the embryo Chorion = Forms part of the placenta Amnion = Surrounds the embryo, forming a protective cavity Allantois = Contributes to umbilical cord formation</p> Signup and view all the answers

    What does the endoderm develop into?

    <p>Internal organs</p> Signup and view all the answers

    The yolk sac has significant nutritional value in adult humans.

    <p>False</p> Signup and view all the answers

    Which layer of the germ disc forms the muscles, bones, and connective tissue?

    <p>Mesoderm</p> Signup and view all the answers

    The _______ is the cavity of the blastocyst.

    <p>Blastocoele</p> Signup and view all the answers

    Which structure develops from the anterior part of the alimentary canal?

    <p>Foregut</p> Signup and view all the answers

    At what stage does the secondary oocyte complete the second meiotic division?

    <p>After fertilization</p> Signup and view all the answers

    The primary oocyte finishes the first meiotic division immediately after puberty.

    <p>False</p> Signup and view all the answers

    What hormone surge is responsible for the final stage of maturation and the rupture of the follicle?

    <p>Combined FSH/LH surge</p> Signup and view all the answers

    The protective layer around the ovum is called the ______.

    <p>zona pellucida</p> Signup and view all the answers

    Match the phase of the menstrual cycle with its description:

    <p>Menstrual Phase = Uterine lining sheds and results in menstrual bleeding Follicular Phase = Ovaries produce follicles and estrogen levels rise Ovulation = Mature egg is released from the dominant follicle Luteal Phase = Empty follicle produces progesterone and prepares the uterus</p> Signup and view all the answers

    Which of the following occurs during the Luteal Phase?

    <p>Progesterone prepares the uterus for a fertilized egg</p> Signup and view all the answers

    Only one secondary oocyte is released in each ovarian cycle.

    <p>True</p> Signup and view all the answers

    What happens to the secondary oocyte if fertilization does not occur?

    <p>It does not complete the second meiotic division and degenerates.</p> Signup and view all the answers

    The process by which the secondary oocyte is released from the ovary is called ______.

    <p>ovulation</p> Signup and view all the answers

    What occurs approximately 14 days prior to the expected menstrual period?

    <p>Ovulation</p> Signup and view all the answers

    Study Notes

    Introduction to Embryology

    • Embryology is the study of the development of an embryo from fertilization to the fetus stage.
    • The embryonic period extends from conception to the third month of development.
    • The fetal period lasts from the third month of development until birth.
    • A teratogen is a substance that can cause developmental abnormalities.

    Terminology

    • A zygote is a fertilized egg, marking the earliest stage of embryonic development.
    • A morula is a compact ball of 16 cells formed on Day 3.
    • The embryoblast, also known as the inner cell mass (ICM), gives rise to the three primary germ layers: endoderm, ectoderm, and mesoderm.
    • A blastocyst forms on Day 4 and consists of a trophoblast surrounding the blastocoele and embryoblast.
    • The trophoblast forms the placenta.
    • The hypoblast forms on Day 8 from the inner cell mass and gives rise to extra-embryonic tissues like the yolk sac, chorion, amnion, and allantois.
    • The epiblast, also developing from the ICM, lies above the hypoblast. Epiblast cells are pluripotent, meaning they can differentiate into any cell type.

    Gastrulation and Trilaminar Germ Disc

    • Gastrulation marks the embryonic phase where the bilaminar germ disc acquires a third germ layer, transforming into the trilaminar germ disc.
    • The trilaminar germ disc consists of the ectoderm, endoderm, and mesoderm.
    • The ectoderm (outer layer) forms the skin, nervous system, hair, and sensory organs.
    • The mesoderm (middle layer) develops into muscles, bones, connective tissue, and the circulatory system.
    • The endoderm (inner layer) gives rise to internal organs such as the lungs, liver, and pancreas.

    Gametogenesis

    • Gametogenesis is the process producing gametes (sperm and egg cells) for sexual reproduction.
    • Spermatogenesis involves the production of sperm cells in the testes.
    • Oogenesis signifies the production of egg cells in the ovaries.

    Oogenesis

    • Oogenesis is the process of forming an ovum (egg) in the ovaries.
    • It involves a series of stages, including the development of oogonia, primary follicles, growing follicles, primary oocytes, secondary follicles, tertiary follicles, and finally, ovulation.
    • At birth, females possess a lifetime supply of developing oocytes, each in Prophase I.
    • A secondary oocyte is released each month from puberty until menopause.
    • The primary oocyte completes the first meiotic division during puberty.
    • The secondary oocyte completes the second meiotic division after fertilization by sperm in the fallopian tube.

    Ovulation

    • Ovulation is the process of releasing the secondary oocyte from the ovary when the mature Graafian follicle ruptures.
    • Usually, only one secondary oocyte is released during an ovarian cycle, which starts at puberty and ends in menopause.
    • Ovulation typically occurs around 14 days before the expected menstrual period.

    Spermatogenesis

    • Spermatogenesis is the process producing sperm cells in the testes.
    • The stages involve spermatocytogenesis and spermiogenesis.
    • Spermatocytogenesis includes the germ cell division and differentiation into spermatogonia, primary spermatocytes, and secondary spermatocytes.
    • Spermiogenesis involves the morphological transformation of spermatids into mature spermatozoa.

    Structure of a Mature Spermatozoon

    • The sperm consists of the head, neck, middle piece, and tail.
    • The head contains the nucleus with haploid chromosomes and the acrosome, which contains digestive enzymes for fertilization.
    • The centrioles are found in the middle piece along with mitochondria, which provide energy for locomotion.
    • The tail enables the sperm's motility.

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    Description

    This quiz covers the fundamentals of embryology, including the stages of development from fertilization to birth. Learn key terminology such as zygote, morula, and blastocyst, as well as the roles of various structures in embryonic development. Test your understanding of these critical concepts in the study of human development.

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