Embryonic Development: Gastrulation and Trophoblast Formation
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Questions and Answers

What is the length of the uterus?

  • 7.5 cm (correct)
  • 10 cm
  • 5 cm
  • 8-10 cm

    • What is the main part of the uterus?

  • Body/Corpus (correct)
  • Fundus
  • Cervix
  • Fallopian tube

    • What is the purpose of the hymen?

  • To guard the external opening of the vagina (correct)
  • To protect the vagina from bacteria
  • To regulate the size of the vaginal orifice
  • To produce hormones

    • What is the name of the inferior narrow portion of the uterus?

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

    What is the size of the uterus in width?

    <p>5 cm</p> Signup and view all the answers

    What is the dome-shaped portion of the uterus?

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

    How long is the vagina approximately?

    <p>8-10 cm</p> Signup and view all the answers

    What lines the vagina?

    <p>Mucous membrane</p> Signup and view all the answers

    What is the process called when cells of the epiblast move inward and detach from the hypoblast?

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

    What is the term for the first major event of the third week of development?

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

    What are the three primary germ layers formed during gastrulation?

    <p>Ectoderm, Endoderm, Mesoderm</p> Signup and view all the answers

    What is the term for the duration between fertilization and childbirth?

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

    What type of placenta is found in humans?

    <p>Haemochorial Placenta</p> Signup and view all the answers

    What is the function of the placenta?

    <p>To provide nutrients and oxygen to the foetus</p> Signup and view all the answers

    What can pass from mother to foetus through the placenta?

    <p>All of the above</p> Signup and view all the answers

    What can cause malformations in the developing embryo?

    <p>Virus infections in the mother</p> Signup and view all the answers

    What is the term for the process by which the yolk sac and amnion are formed?

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

    How long is the gestation period in cats?

    <p>52-65 days</p> Signup and view all the answers

    What is the primary function of the corpus luteum?

    <p>To produce estrogen and progesterone</p> Signup and view all the answers

    What is the primary hormone involved in lactation?

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

    What is the name of the first milk produced after childbirth?

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

    What is the primary function of inhibin?

    <p>To inhibit follicular development</p> Signup and view all the answers

    What is the name of the structure that forms in the ovary after ovulation?

    <p>Corpus luteum</p> Signup and view all the answers

    What is the name of the hormone that stimulates ovulation?

    <p>Luteinizing hormone (LH)</p> Signup and view all the answers

    What is the term for the cessation of menstruation during lactation?

    <p>Lactational amenorrhea</p> Signup and view all the answers

    What is the primary function of oxytocin?

    <p>Stimulate milk letdown</p> Signup and view all the answers

    What is the term for the process by which sperm capacitate in the female reproductive tract?

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

    What is the term for the structure that forms during embryonic development?

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

    What is the total duration of human gestation?

    <p>280 days</p> Signup and view all the answers

    What is the primary function of the placenta?

    <p>To produce hormones</p> Signup and view all the answers

    During which trimester do most major organs and systems form?

    <p>First trimester</p> Signup and view all the answers

    What hormone is responsible for inhibiting uterine contractions?

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

    When do eyelids separate and eyelashes form?

    <p>Second trimester</p> Signup and view all the answers

    What is the function of human chorionic gonadotropin (hCG)?

    <p>To induce fetal pituitary hormone release</p> Signup and view all the answers

    What is the purpose of prostaglandin in childbirth?

    <p>To induce uterine contractions</p> Signup and view all the answers

    What is the foetus ejection reflex?

    <p>A reflex that helps to expel the fetus during childbirth</p> Signup and view all the answers

    At what stage is abortion considered safe for the mother?

    <p>First trimester</p> Signup and view all the answers

    What is the primary function of relaxin in childbirth?

    <p>To relax the cervix</p> Signup and view all the answers

    What is the process of attachment or embedding of the developing blastocyst with the wall of the uterus?

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

    What is the purpose of lytic enzymes released from the trophoblast during implantation?

    <p>To break down the uterine lining for implantation</p> Signup and view all the answers

    What is the term for the uterine lining after implantation?

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

    During which stage of development does the formation of the primitive streak occur?

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

    What is the result of morphogenetic movements during gastrulation?

    <p>Formation of three germ layers</p> Signup and view all the answers

    What is the process of delamination?

    <p>Formation of a secondary layer by division of a primary layer</p> Signup and view all the answers

    What is the term for the movement of the blastocyst into the uterine wall during implantation?

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

    What is the significance of the trophoblast during implantation?

    <p>It releases lytic enzymes for implantation</p> Signup and view all the answers

    Study Notes

    Uterus

    • Size: 7.5 cm long, 5 cm wide, and 2.5 cm thick
    • Composed of three parts:

      Parts of Uterus

      • Fundus: upper dome-shaped portion superior to the uterine tubes
      • Body/Corpus: middle part and main part of the uterus
      • Cervix: inferior narrow portion that opens into the vagina

    Vagina

    • A tubular, 8-10 cm long canal lined with mucous membrane

    • External opening is the vaginal orifice

    • Guarded by a thin fold of vascularized mucous membrane called the hymen### Hymen and Virginity

    • The hymen can be broken during the first sexual intercourse, but it can also be broken by other means such as a sudden fall, insertion of a vaginal tampon, or active participation in sports like horseback riding or cycling.

    • The presence or absence of the hymen is not a reliable indicator of virginity or sexual experience.

    Vulva and External Genitalia

    • The vulva consists of the paraurethral glands, which produce bacteria-lactobacillus acidophilus.

    ForeSkin and Prepuce

    • The foreskin, also known as the prepuce, covers the glans penis and can be retracted back over the shaft of the penis.

    Hormonal Regulation of Lactation

    • Prolactin, produced by the anterior pituitary gland, stimulates milk production during lactation.
    • Estrogen and progesterone prepare the body for pregnancy, and oxytocin stimulates milk ejection.
    • The sucking action of the baby on the nipple stimulates prolactin secretion, which maintains lactation.

    Composition of Human Milk

    • Human milk contains lactose, casein (milk protein), and minerals like sodium, potassium, calcium, and phosphorus.
    • Vitamins and passive immunity are also present in human milk.

    Follicular Development

    • Primary follicles develop from primordial follicles in the embryonic stage.
    • The first meiotic division of oogenesis occurs in the fetal stage, and the second meiotic division occurs at the time of fertilization.
    • Graafian follicles are the mature follicles that release an ovum during ovulation.

    Menstrual Cycle

    • The menstrual cycle is the phase between two menstruations, lasting around 28 days.
    • The follicular phase starts at menstruation, and ovulation occurs around the 14th day.
    • The luteal phase starts after ovulation and lasts until the next menstruation.

    Ovulation and Fertilization

    • Ovulation occurs when the ovum is released from the Graafian follicle.
    • Fertilization occurs when a sperm fertilizes the ovum in the fallopian tube, resulting in a zygote with 46 chromosomes.
    • The zygote then travels down the fallopian tube and into the uterus, where it implants in the endometrium.### Embryonic Development
    • Gastrulation begins with the formation of the primitive streak on the surface of the epiblast, around 7-9 days after fertilization.
    • During gastrulation, three germ layers are formed by morphogenetic movement of blastomeres: ectoderm, endoderm, and mesoderm.

    Implantation

    • Implantation is the attachment or embedding of the developing blastocyst with the wall of the uterus (endometrium) with the help of lytic enzymes.
    • The blastocyst completely sinks into the wall of the uterus, and the endometrium becomes more vascularized.
    • After implantation, the endometrium is known as the decidua.

    Placenta

    • The placenta is a structural and functional unit between the developing embryo and maternal body.
    • It is responsible for the exchange of nutrients, hormones, gases, and antibodies between the mother and foetus.
    • The placenta acts like an endocrine gland and releases hormones such as progesterone, human chorionic gonadotrophin, and human placental lactogen.

    Gestation Period

    • The gestation period is the duration between fertilization and parturition (childbirth).
    • In humans, the gestation period is approximately 9 months, 38 weeks, or 266 days.
    • The gestation period is divided into three trimesters: first trimester (1-3 months), second trimester (4-6 months), and third trimester (7-9 months).

    Fetal Development

    • During the first trimester, the major organs and systems are formed.
    • During the second trimester, the fetus develops limbs and digits, and most organs are well-developed.
    • During the third trimester, the fetus continues to grow and develop, and the body is covered with fine hair (lanugo).

    Parturition

    • Parturition is the process of childbirth, which is triggered by the release of hormones such as oxytocin and progesterone.
    • The foetus is fully developed and ready for parturition by the end of the gestation period.
    • The placenta releases hormones that stimulate uterine contractions and help in the expulsion of the fetus during childbirth.

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    Description

    Learn about the process of gastrulation and formation of trophoblast, a crucial stage in embryonic development. Understand the attachment and embedding of the developing embryo.

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