Ovarian Cycle Overview
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Questions and Answers

What initiates the ovarian cycle?

  • Luteinizing hormone (LH)
  • Follicular stimulating hormone (FSH)
  • Corpus luteum formation
  • Hypothalamic impulses (correct)

Which hormone is primarily responsible for stimulating follicle growth?

  • Progesterone
  • Estrogen
  • Luteinizing hormone (LH)
  • Follicular stimulating hormone (FSH) (correct)

What occurs after the release of the mature ovum from the follicle?

  • Formation of the primordial follicle
  • Degeneration of the mature follicle
  • Development of the corpus luteum (correct)
  • Hypothalamic stimulation increases

What happens to the corpus luteum if fertilization does not occur?

<p>It degenerates (B)</p> Signup and view all the answers

Which of the following statements best describes the ovarian cycle?

<p>It includes complex interactions between hormones and follicle maturation. (D)</p> Signup and view all the answers

What initiates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) during the ovarian cycle?

<p>Gonadotropin-releasing hormone (GnRH) from the hypothalamus (C)</p> Signup and view all the answers

What role does FSH play in the growth of ovarian follicles?

<p>It stimulates the degeneration of the majority of follicles. (D)</p> Signup and view all the answers

What occurs during the LH surge at mid-cycle?

<p>Meiosis I is completed and meiosis II is initiated in oocytes. (B)</p> Signup and view all the answers

Which hormone is primarily involved in the production of androgens during follicle maturation?

<p>Theca interna cells (A)</p> Signup and view all the answers

What happens during the ovulatory phase regarding the ovarian surface?

<p>The ovarian surface bulges creating a stigma. (A)</p> Signup and view all the answers

Which of the following correctly describes the role of prostaglandins during ovulation?

<p>They induce muscular contractions in the ovarian wall. (B)</p> Signup and view all the answers

What type of tissue is formed from the degeneration of atretic follicles?

<p>Corpus atreticum (D)</p> Signup and view all the answers

What is the diameter of the mature vesicular follicle before ovulation?

<p>25 mm (B)</p> Signup and view all the answers

What is the primary mechanism that facilitates sperm movement from the cervix to the uterine tube?

<p>Muscular contractions (D)</p> Signup and view all the answers

During which phase of fertilization does the inner acrosomal membrane dissolve?

<p>Penetration of the zona pellucida (A)</p> Signup and view all the answers

What percentage of sperm deposited in the vagina is likely to reach the cervix?

<p>1% (B)</p> Signup and view all the answers

Where does fertilization primarily occur within the female reproductive system?

<p>Ampullary region of the uterine tube (B)</p> Signup and view all the answers

What role does the polar body play during the fertilization process?

<p>It undergoes division. (A)</p> Signup and view all the answers

What significant event occurs during the formation of the corpus luteum?

<p>Granulosa and theca interna cells accumulate lipids. (B)</p> Signup and view all the answers

How does human chorionic gonadotropin (hCG) affect the corpus luteum after fertilization?

<p>Promotes progesterone production and prevents its degeneration. (B)</p> Signup and view all the answers

What role do fimbriae play in the ovarian cycle?

<p>They collect the oocyte and guide it into the uterine tube. (B)</p> Signup and view all the answers

What is the primary hormone secreted by the corpus luteum?

<p>Progesterone (A)</p> Signup and view all the answers

What occurs if the corpus luteum is removed before the fourth month of pregnancy?

<p>It usually leads to an abortion. (D)</p> Signup and view all the answers

What occurs during ovulation?

<p>The oocyte is released along with cumulus oophorus cells. (C)</p> Signup and view all the answers

Which condition results in a large corpus luteum due to the gestational phase?

<p>If the oocyte is fertilized. (A)</p> Signup and view all the answers

What is the primary function of the zona pellucida in fertilization?

<p>To facilitate and maintain sperm binding (D)</p> Signup and view all the answers

Which phase of fertilization involves the acrosome reaction?

<p>Penetration of the Zona Pellucida (C)</p> Signup and view all the answers

During which process is sperm coated with glycoprotein removed?

<p>Capacitation (C)</p> Signup and view all the answers

What occurs after sperm reach the isthmus in terms of motility?

<p>Sperm motility decreases before re-motility in the ampulla (B)</p> Signup and view all the answers

What characterizes the conditioning process of sperm known as capacitation?

<p>Interaction with the uterine tube lining (D)</p> Signup and view all the answers

What is the role of ZP3 in the fertilization process?

<p>To mediate sperm binding to the zona pellucida (B)</p> Signup and view all the answers

Which event occurs immediately after the sperm enters the oocyte?

<p>Completion of the second meiotic division (D)</p> Signup and view all the answers

During the fusion of sperm and oocyte membranes, which part of the sperm typically participates in the fusion?

<p>The posterior region of the sperm head (B)</p> Signup and view all the answers

What initiates early embryogenesis and metabolic activation of the egg?

<p>A factor carried by the sperm (C)</p> Signup and view all the answers

What happens to the male pronucleus after the sperm nucleus swells?

<p>It duplicates its DNA for the two-cell zygote (B)</p> Signup and view all the answers

What triggers the transition of a growing follicle to a vesicular follicle?

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

What is the main role of the corpus luteum after ovulation?

<p>To secrete progesterone and estrogens (B)</p> Signup and view all the answers

Which stage of follicle development is characterized by the presence of a fluid-filled antrum?

<p>Vesicular follicle (B)</p> Signup and view all the answers

What physiological response may some women experience during ovulation?

<p>Mild pain known as mittelschmerz (A)</p> Signup and view all the answers

How does the oocyte reach the uterine lumen after ovulation?

<p>Via peristaltic muscular contractions and ciliary action (B)</p> Signup and view all the answers

What triggers oocyte transport into the uterine tube shortly before ovulation?

<p>Sweeping of fimbriae and rhythmic contractions of the tube (B)</p> Signup and view all the answers

What hormonal changes occur just before ovulation?

<p>Surge in LH due to estrogen stimulation (A)</p> Signup and view all the answers

Which type of follicle contains a primary oocyte surrounded by follicular cells?

<p>Primordial follicle (C)</p> Signup and view all the answers

What effect does LH have on the mating stage of the follicle?

<p>It induces the completion of meiosis I (C)</p> Signup and view all the answers

What triggers the cortical and zona reactions in the oocyte?

<p>Direct contact between sperm and oocyte (C)</p> Signup and view all the answers

Which change occurs to the zona pellucida after sperm penetration?

<p>It is chemically altered to inactivate sperm receptors. (D)</p> Signup and view all the answers

What happens immediately after the entry of sperm into the oocyte?

<p>The oocyte completes its second meiotic division. (C)</p> Signup and view all the answers

What is the role of integrins in the fertilization process?

<p>They help in the initial adhesion of sperm to the oocyte. (D)</p> Signup and view all the answers

What occurs to the sperm nucleus after it enters the oocyte?

<p>It swells, forming the male pronucleus. (B)</p> Signup and view all the answers

Why is it essential for each pronucleus to replicate its DNA before division?

<p>To ensure both cells have equal genetic information. (B)</p> Signup and view all the answers

What prevents polyspermy during the fertilization process?

<p>Chemical changes in the zona pellucida after one sperm penetrates. (D)</p> Signup and view all the answers

What ultimately happens to the sperm's tail after entering the oocyte?

<p>It detaches and degenerates. (D)</p> Signup and view all the answers

What is a common outcome associated with ART conceptions in terms of birth weight?

<p>Increased likelihood of very low birth weight (C)</p> Signup and view all the answers

What is the primary purpose of ICSI in assisted reproductive technology?

<p>To overcome severe male infertility (D)</p> Signup and view all the answers

At what maternal age does the success rate of IVF drop to less than 5%?

<p>Over 40 (C)</p> Signup and view all the answers

Which stage of cleavage occurs after the zygote becomes a compacted ball of cells?

<p>Morula stage (D)</p> Signup and view all the answers

What differentiates the inner cell mass from the outer cell mass during the cleavage process?

<p>Outer cells form the structure of the blastocyst (A)</p> Signup and view all the answers

Which reproductive technology is more likely to result in multiple births?

<p>In Vitro Fertilization (IVF) (A)</p> Signup and view all the answers

What is a critical factor that affects the success rates of assisted reproductive technology?

<p>The age of the maternal partner (A)</p> Signup and view all the answers

What is a key risk associated with the use of ICSI in assisted reproductive technology?

<p>Higher likelihood of genetic abnormalities (C)</p> Signup and view all the answers

What is the expected outcome of fertilization regarding chromosome numbers and composition?

<p>Restoration of the diploid number of chromosomes, with half from each parent. (C)</p> Signup and view all the answers

Which contraceptive method primarily works by directly preventing sperm from entering the uterus?

<p>Barrier methods including condoms and diaphragms. (C)</p> Signup and view all the answers

Which of the following statements regarding hormonal contraceptive pills is true?

<p>Combination pills usually include both estrogen and progestin. (B)</p> Signup and view all the answers

What is a common cause of male infertility as described?

<p>Insufficient sperm counts or poor motility. (C)</p> Signup and view all the answers

What characterizes hormonal intrauterine devices (IUDs)?

<p>They release progestin, affecting the uterine lining. (C)</p> Signup and view all the answers

What is a significant factor that can affect female infertility?

<p>Issues with the reproductive anatomy, such as blocked tubes. (D)</p> Signup and view all the answers

What is the mechanism of action for emergency contraceptive pills (ECPs)?

<p>They prevent ovulation or alter the uterine lining to prevent implantation. (C)</p> Signup and view all the answers

What is the normal expected sperm concentration in a healthy male ejaculate?

<p>100 million sperm/mL (D)</p> Signup and view all the answers

Flashcards

Ovarian Cycle

A monthly cycle in females, controlled by hormones, leading to possible fertilization.

Follicle Maturation

FSH and LH stimulate the growth of follicle cells, leading to ovum release.

LH Surge

A peak in LH levels during the mid-cycle, triggering ovulation.

Ovulation

The release of a mature egg from the follicle.

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Meiosis I Completion

The primary oocyte completes the first stage of meiosis in response to the LH surge.

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Corpus Atreticum

Degenerate follicles (scar tissue) after failed ovulation.

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FSH function

Stimulates follicle growth and prevents premature death of follicle cells.

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LH function

Triggers ovulation and Progesterone production by the ruptured follicle.

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Ovarian Cycle Stages

The sequence of events in the ovary, from follicle maturation to ovulation and corpus luteum formation.

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Corpus Luteum

Structure that forms after ovulation and produces hormones.

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Hormonal Regulation (Ovarian Cycle)

Hypothalamic hormones and gonadotropins (like FSH and LH) drive the ovarian cycle.

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Fertilization

The fusion of male and female gametes (sperm and egg) resulting in a zygote.

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Ampullary region

The widest part of the uterine tube where fertilization typically occurs.

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Corona Radiata

Layer of cells surrounding the oocyte, acting as a barrier for sperm penetration.

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Zona Pellucida

Thick glycoprotein layer surrounding the oocyte, acting as a second barrier that sperm must penetrate.

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Acrosomal Reaction

The release of enzymes from the sperm's acrosome, allowing it to penetrate the zona pellucida.

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Primordial Follicle

The earliest stage of follicle development, containing a primary oocyte surrounded by a single layer of follicular cells.

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Growing Follicle

A developing follicle with a primary oocyte surrounded by granulosa cells and an inner and outer theca layer.

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Vesicular Follicle

A mature follicle with a fluid-filled antrum and the zona pellucida surrounding the oocyte.

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What triggers follicle maturation?

FSH stimulates the growth of follicles, transitioning them from growing to vesicular follicles.

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How does LH affect ovulation?

An LH surge causes the final maturation of the vesicular follicle, leading to ovulation.

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What happens after ovulation?

The remaining follicle cells develop into the corpus luteum, secreting estrogen and progesterone.

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What is the function of progesterone?

Progesterone prepares the uterine lining for implantation of a fertilized egg.

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How are oocytes transported?

Oocytes are swept into the uterine tube by fimbriae and cilia, then transported by peristaltic contractions and cilia.

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What is the Corpus Albicans?

The corpus luteum shrinks and degenerates into the corpus albicans if fertilization does not occur.

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What happens to the oocyte if fertilization doesn't occur?

The oocyte is reabsorbed by the body, and the menstrual cycle begins again.

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Sperm's First Goal

The sperm's initial task is to penetrate the corona radiata, a layer of cells surrounding the egg.

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Zona Pellucida's Role

The zona pellucida is a protective glycoprotein layer around the egg. It facilitates sperm binding, induces the acrosome reaction, and ensures only one sperm fertilizes the egg.

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Capacitation: Sperm's Preparation

Capacitation is a conditioning process in the oviduct that makes sperm capable of fertilizing the egg. It involves losing its glycoprotein coat and seminal plasma proteins.

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Sperm Motility: Traveling to the Egg

Sperm's motility changes as they travel. It slows down in the isthmus and reactivates in the ampulla, guided by chemoattractants from the egg.

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What is the corpus luteum?

A temporary endocrine gland formed from the ruptured follicle after ovulation. It produces progesterone to prepare the uterus for implantation.

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What happens to the corpus luteum if fertilization DOESN'T occur?

The corpus luteum degenerates into a scar tissue (corpus albicans) and progesterone levels decrease, leading to menstruation.

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What happens to the corpus luteum if fertilization DOES occur?

The corpus luteum is maintained by hCG (human chorionic gonadotropin) produced by the developing embryo, sustaining progesterone production until the placenta takes over.

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Function of Fimbriae

Finger-like projections at the end of the fallopian tube that collect the released egg and guide it towards the uterus.

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What is luteolysis?

Degeneration of the corpus luteum, causing a decrease in progesterone production, and leading to menstruation if fertilization doesn't occur.

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What is hCG?

Human Chorionic Gonadotropin, a hormone produced by the developing embryo, that prevents the corpus luteum from degenerating and ensures progesterone production.

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Progesterone's role during pregnancy

Progesterone maintains the uterine lining for implantation and supports the development of the fetus until the placenta takes over its production.

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Zona Pellucida Protein

A protein on the outer layer of the egg that sperm binds to, initiating fertilization.

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Cortical Reaction

Release of oocyte granules to alter the zona pellucida, preventing other sperm from entering.

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Pronuclei Fusion

The merging of the male and female pronuclei, combining genetic material to form a diploid zygote.

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What triggers the start of embryogenesis?

A factor carried by the sperm initiates early embryonic development, involving cell division and molecular events.

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What prevents polyspermy?

The release of lysosomal enzymes from cortical granules alters the zona pellucida's properties to prevent multiple sperm from fertilizing the oocyte.

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What happens to the oocyte after sperm entry?

The oocyte completes its second meiotic division, resulting in the formation of a second polar body and the definitive oocyte with a vesicular nucleus (female pronucleus).

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What is the role of integrins in fertilization?

Integrins on the oocyte surface interact with their ligands, disintegrins, on the sperm during initial sperm adhesion to the oocyte.

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What triggers metabolic activation of the egg?

Sperm entry triggers metabolic activation, initiating the cellular and molecular events of early embryogenesis.

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What happens to the sperm nucleus after entering the oocyte?

The sperm nucleus swells, forming the male pronucleus, while the tail detaches and degenerates.

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What happens to the male and female pronuclei?

The male and female pronuclei, morphologically indistinguishable, come into close contact and lose their nuclear envelopes.

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What is the result of pronuclei replicating their DNA?

Each pronucleus replicates its DNA before dividing, ensuring each cell of the two-cell zygote has the normal amount of DNA.

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What is the purpose of chromosomes organizing on the spindle?

Chromosomes organize on the spindle in preparation for a normal mitotic division, leading to the formation of two daughter cells.

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Diploid Number

The normal number of chromosomes in a cell, with two sets of each chromosome (one from each parent).

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Sex Determination

The process of establishing the sex of an individual, determined by the sperm's X or Y chromosome, resulting in XX (female) or XY (male).

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Barrier Contraceptive Methods

Methods that physically prevent sperm from entering the uterus, such as condoms, diaphragms, and cervical caps.

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Hormonal Contraceptives

Methods that use hormones (estrogen and/or progestin) to prevent pregnancy by inhibiting ovulation or changing the uterine lining.

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Intrauterine Device (IUD)

A small device inserted into the uterus to prevent pregnancy, either by releasing hormones (progestin) or containing copper.

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Emergency Contraceptive Pills (ECPs)

Pills taken after unprotected intercourse to prevent pregnancy by delaying ovulation or preventing implantation.

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Male Infertility

Inability of a male to father a child due to insufficient sperm numbers or poor sperm motility.

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Female Infertility

Inability of a female to conceive a child due to various factors, including ovulation issues, blocked fallopian tubes, and uterine problems.

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ART Success Rates

The effectiveness of Assisted Reproductive Technologies (ART) depends heavily on the mother's age. Success rates decline sharply after 35, with less than a 5% chance of success for women over 40.

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ART Complications

Babies conceived through ART have increased risk of prematurity, low birth weight, and birth defects compared to natural conceptions.

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IVF vs. ICSI

IVF combines sperm and egg in a lab dish; ICSI directly injects a sperm into an egg, often used for severe male infertility.

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Cleavage

The zygote undergoes repetitive divisions after fertilization, creating smaller cells called blastomeres.

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Compaction

Blastomeres form a tight ball of cells held together by junctions, separating inner cells (future embryo) from outer cells (future placenta).

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Morula

A 16- cell stage compacted embryo, with inner cells forming the embryo and outer cells forming the trophoblast (precursor to placenta).

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Inner Cell Mass Fate

The inner cell mass of the morula develops into the embryo's tissues, including organs and systems.

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Trophoblast Fate

The outer layer of the morula, called the trophoblast, contributes to the placenta, the organ that supports the developing embryo.

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