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BIOM3200 > Sex Determination and Differentiation > Flashcards

Sex Determination and Differentiation Flashcards

1
Q

What hormones are necessary for breast milk?

A

Prolactin and GH

  • These are the only two anterior pituitary hormones whose section is controlled by both releasing and inhibiting hormones.
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2
Q

Prolactin activates the _____ of the breast.

A

Mammary gland

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3
Q

The mammary gland has approximately ____ milk lobes divided by adipose tissue.

A

15-20

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4
Q

Each lobe of the mammary gland is subdivided into lobules, which contain _____, which secrete milk.

A

Alveoli

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5
Q

Alveoli secrete milk into the secondary tubules, which form into mammary ducts, then the __________, then they drain at the nipple.

A

Lactiferous duct

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6
Q

The _____ of the duct is where milk accumulated during nursing.

A

Lumen

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7
Q

The _____ produce and contain the milk in the lumen.

A

Alveoli

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8
Q

The anterior pituitary releases prolactin, which acts on the ______ to stimulate milk production and growth/development of glands and ducts.

A

Mammary glands

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9
Q

Why is milk production prevented during pregnancy?

A

Because estrogen is high and the secretin of prolactin is inhibited. A high level of estrogen stimulates the hypothalamus to inhibit PIH, which inhibits the anterior pituitary from releasing prolactin. After birth, the placenta is gone, and estrogen levels go down, so there is an increase in secretion of prolactin.

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10
Q

Prolactin is secreted from the ______. Milk is PRODUCED under this control.

A

Anterior pituitary.

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11
Q

What hormone is required to release breast milk?

A

Oxytocin

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12
Q

Where is oxytocin produced/released from?

A

Posterior pituitary

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13
Q

What action from babies to mother stimulates and triggers oxytocin and release.

A

Sucking of breast - This is a sensory input that triggers the hypothalamus to release oxytocin and prolactin

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14
Q

The release of oxytocin can be stimulated by visual or ______ cues (brain stimuli). Even a thought of the child can do this.

A

Auditory

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15
Q

Posterior pituitary –> _______ –> Milk ejection

A

Oxytocin

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16
Q

Anterior pituitary –> Prolactin —> ________

A

Milk production

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17
Q

Oxytocin increases _____ in humans.

A

Trust

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18
Q

Intranasal (through the nose) administration of oxytocin, a neuropeptide plays a key role in ___________.

A

Social attachment and affiliation in non-human animals

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19
Q

Describe the effects of intranasal administration of oxytocin.

A

Causes a substantial increase in trust among humans, thereby greatly increasing the benefits from social interactions.

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20
Q

What determines biological sex?

A

A particular gene on the Y chromosome induces the embryonic gonads to become testes. Biological females lack a Y chromosome, and the absence of this gene causes development of ovaries.

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21
Q

A gene known as ________ is thought to be important for male determination. This gene is found on the Y chromosome of all animals and is highly conserved.

A

SRY (Sex determining Region of the Y)

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22
Q

In the fetus, the sex differentiation begins with the development of the gonad from a _____________.

A

Bipotential primordium

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23
Q

Describe the development of a female at the 10 weeks mark form the biopotential primordium.

A

No Y chromosome-tissue develops into ovaries - no testosterone or sertoli cells

  1. Absence of SRY protein, so the gonadal tissue develops into the ovaries.
  2. There is no testosterone. There is no Sertoli cells, and therefore there is a lack of MIF (Mullein inhibition factor). Without MIF, Wolffian duct degenerates. The Mullerian duct presence is MAINTAINED.
  3. The absence of MIF allows the Müllerian duct to become the Fallopian tubes, uterus, and the vagina.
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24
Q

Describe the development of a male at the 10 weeks mark form the biopotential primordium.

A

There is a Y chromosome.

  1. Presence of the SRY protein allows the gonadal tissue to develop into the testes.
  2. In the presence of testosterone, MIF is made from Sertoli cells, which causes the Wolffian duct to be maintained. However, the Müllerian duct DEGENERATES in males.
  3. Testosterone allows the Wolffian duct to become the seminal vesicles, vas deferent, and epididymis.
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25
Q

All nucleated cells in the body except eggs and sperm contain ________ (#) chromosomes (diploid).

A

46

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26
Q

There are ____ (#) homologous (matched) pairs of autosomes and ___ (#) pair of sex chromosomes.

A

22, 1

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27
Q

Egg and sperm contain half a set of ____ (#) chromosomes (haploid).

A

23

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28
Q

Genetic females are ____ (letters). They inherit one from the mother and one from the father.

A

XX

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29
Q

Genetic males are ___ (letters). Which letter is inherited from which parent?

A

XY

X - Mother
Y - Father

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30
Q

What is it about the Y chromosome that determines male or female?

A

The SRY gene. The SRY gene is the ultimate “maleness gene”. The action after 6 weeks after conception triggers formation of the testes (from the primordial gonads). The testes produce testosterone, which form the male traits. Without the SRY gene, a fetus would develop into female.

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31
Q

Testis determination requires _______ receptor family function.

A

Insulin.

With the activation of the:

  1. Insulin receptor (INSR)
  2. Insulin-like growth factor 1 receptor (IGF1R)
  3. Insulin receptor-related receptor (INSSR)

SRY positive, XY positive –> 3 mice exhibiting mutations for all three of these receptors developed ovaries and showed a complete female phenotype

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32
Q

What is a true hermaphrodites?

A

An intersex individual where they patient can have both ovaries and testes tissue and can be 46XX with SRY mosaicism.

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33
Q

List the karyotypes for true hermaphrodites.

A
  • 47XXY
  • 46XX/46XY
  • 46XX/47XXY
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34
Q

How often is a child born with noticeable atypical genetalia?

A

1/1500 to 1/2000 births (0.07-0.05%)

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35
Q

Describe pseudohermaphordites?

A

Congenital condition- person has external genitals of one sex and internal sex organs of the other gender.

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36
Q

Pseudohermaphorditism is what kind of disorder?

A

Endocrine disorder

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37
Q

Regardless of the female genitalia, pseudohermaphordites are males with a defective gene for ___________.

A

5a-reductase

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38
Q

In pseudohermaphorditism, patients have _______ testosterone levels, _______ 5a-reductase, and inadequate levels of DHT.

A

Normal, defective

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39
Q

Pseudohermaphorditism can occur due to what kind of factors?

A

Inappropriate exposure to androgens during early gestation.

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40
Q

Describe characteristics of pseudohermaphorditism.

A
  • Male external genetalia and prostate gland fail to develop fully during fetal development.
  • At birth they appear female and are raised as such.
  • At puberty testes secrete testosterone again.
  • Causes masculinization of the external genitalia, voice, etc.
41
Q

Puberty is known as the activation of the _________ resulting in gonad maturation.

A

HPG axis

42
Q

Define adolescence.

A

Maturation of adult social and cognitive behaviours.

43
Q

GnRH release occurs in ______ rather than steady.

A

Pulses

44
Q

In children with GnRH deficiencies, treating with steady infusions of GnRH through drug-delivery pumps results in children who _________.

A

Fail to mature sexually.

45
Q

In children with GnRH deficiencies, treating with GnRH pulses similar to those that occur naturally result in children who _________.

A

Successfully go through puberty. An increase in pulsatile GnRH triggers puberty.

46
Q

Describe causes of variations in puberty.

A
  • Genetic variations in timing of onset of puberty.
  • Environmental factors (Increased altitude = Later onset)
  • Nutrition (Anorexia)
  • Chronic illnesses (IBD, TB)
  • Theoretical concern over synthetic hormones, other environmental chemicals (drop of several months (Can affect the onset of puberty)
  • Precocious puberty (Very early onset puberty)
47
Q

In order for ovulation to occur, there must be a surge of ________.

A

LH

48
Q

2 days before ovulation, LH increases by a _______ fold and FSH increases by a ______ fold.

A

LH –> 6-10 fold
FSH –> 2-3 fold

49
Q

In the ovulation cycle, LH converts ____ and theca cells to progesterone producing cells.

A

Granulosa (Review the diagram on slide 59)

50
Q

How long does the human egg cell take to drop in the fallopian tube?

A

72 hours

51
Q

When can fertilization occur based on the sperm cell life?

A

Sperm can survive up to three days in the female reproductive tract. Fertilization can occur if intercourse takes place within a three day period prior to the day of ovulation. Fertilization can not occur later the 1-day post ovulation.

52
Q

The secondary oocyte following ovulation disintegrates _______ hours after ovulation if it doesn’t go into its division cycles.

A

12-24 hours (Review the diagram on slide 62)

53
Q

Ejaculated sperm deposited in the vagina must travel and mature before fertilization. What is this maturation called and what does it involve?

A

Capacitation- Final maturation enabling them to swim quickly and fertilize an egg. This involves reorganization of molecules in the outer membrane of the sperm head.

54
Q

Describe the time and availability of sperm and eggs after release for fertilization.

A

The egg can be fertilized for only 12 hours post-ovulation. The sperm is viable in females for up to three days.

55
Q

How much do humans ejaculate in mL at one time.

A

2-6 mL

56
Q

In the 2-6 mL of ejaculate, how much spermatozoa are involved and what are they mixed with?

A

40-120 million spermatozoa are mixed with mildly alkaline fluids from seminal vesicles (60%) and the prostate (30%).

57
Q

What is the range of pH in ejaculate?

A

Between 7-8.3

58
Q

How many sperm reach the Fallopian tubes approximately?

A

Approximately 100.

59
Q

Describe the barriers and pathways that sperm tunnel through to get to the egg and fertilize it.

A
  1. Penetrate the outer layer granulosa cells (Corona radiata)
  2. Penetrate the protective glycoprotein coat (Zona pellucida)
60
Q

After a sperm has reached the egg, an electrical polyspermy blocks function in some animals. Do mammals have this

A

Mammals do not have this electrical block. Polyspermy is thought t be prevented by formation of a secreted chemical barrier.

61
Q

Where do ovulation, fertilization, and implantation take place?

A

Review slide 68.

  • Egg is released from the ovary.
  • During ovulation the egg is released and it travels through the fimbira where fertilization takes place and the sperm meets the egg.
  • In Days 2-4, cell division takes place.
  • In Days 4-5, the blastocyst reaches the uterus (At 100 cells)
  • In Days 5-9, the blastocysts implants
62
Q

What does the inner and outer membrane of the blastocyts beomce?

A

Inner –> Embryo
Outer –> Trophectoderm

63
Q

How do dizygotic (fraternal or heterologous) twins form?

A

Develop from two separate oocytes fertilized at the same time.

64
Q

How do monozygotic (identical) twins form?

A

Two individuals developed from one fertilized oocyte. They have identical genomes.

65
Q

How do conjoined twins form?

A

Monozygotic twins whose bodies are joined to a varying extent.

66
Q

Implantation (nidation) of the blastocysts involves the _______, which are cells that produce enzymes that allow blastocyst to “eat its way” into the endometrium.

A

Trophoblast

67
Q

Trophoblast cells secrete hCG (human chorionic gonadotropin) to maintain the mother’s _______.

A

Corpus luteum

68
Q

What is the purpose of a maintained corpus luteum in women?

A

To make progesterone until the fetal placenta can take over.

69
Q

The body produces ____ to implant the blastocyst into the uterine wall on the 6th day after fertilization. 75% of pregnancies are due to failure to implantation.

A

Enzymes

70
Q

What is an ectopic pregnancy?

A

Implantation in a different set than the posterior wall of the uterine cavity. (0.25 to 1%). They are not viable.

71
Q

Describe tubal pregnancies (Endometriosis, prior surgery, pelvic inflammatory diseases).

A

Extra growth in the uterus in the late 30s when trying to get pregnant.

72
Q

How does placenta previa occur?

A

Placenta previa is a problem during pregnancy when the placenta completely or partially covers the opening of the uterus (cervix).

The embryo implant close to the cervix, normal embryonic development occurs, but the placenta partially covers the cervical canal, leading to placenta previa.

73
Q

What is the percentage of each type of ectopic pregnancy?

A

Cervical - 0.3%
Ovarian - 0.5%
Intramural - 2%
Isthmic - 25%
Ampullar - 54%
Infundibular - 17%

74
Q

After fertilization, in blood work, there is a noticed surge in which protein/hormone?

A

Human chorionic gonadotropin (hCG)

75
Q

Is hCG (Human chorionic gonadotropin) secreted by the blastocysts or the mother?

A

The blastocysts.

76
Q

How are hormones measured by immunoassay?

A

Tagged Ab specific to hormone is detected in the blood and urine. The antibody is connected to tagged hCG and this is displayed through the dyes on pregnancy tests.

77
Q

What keeps the pregnancy going before the placenta is formed?

A

hCG from the blastocyst that maintains the corpus luteum.

78
Q

Why is the corpus luteum needed to synthesize progesterone?

A

In early pregnancy, the corpus luteum synthesizes:

a. Progesterone to keep the endometrium intact
b. Progesterone, estrogen, inhibin to maintain feedback suppression to the pituitary

79
Q

Why is the placenta required for pregnancy?

A

Placental a2-adrenoceptors control vascular development at the interface between mother and embryo. Proper development of the placental vascular system is essential to nutrient and gas exchange between mother and developing embryo. During intrauterine life, the placenta performs the functions of the digestive, respiratory, and renal systems and for the “parasitic” fetus.

Exchange of nutrients/waste by the placenta:
- Oxygen/Carbon dioxide
- Chemical agents (drugs, pollutants)

80
Q

What is the single most preventable cause of illness and death among mothers and infants?

A

Smoking

81
Q

Why is the placenta a unique endocrine gland?

A

It is transient (only here for a little while), without extrinsic control.

82
Q

What is the main function of hCG until the placenta takes over.

A

Maintains the corpus luteum.

83
Q

What is the role of estrogen ?

A

Uterine myometrium (growth, oxytocin receptors) and breast ducts

84
Q

What is the role of progesterone?

A

Suppresses uterine contractions, cervical plug, milk glands.

85
Q

What is the role of PTHrP (parathyroid hormone related peptide)?

A

Mobilizes the mothers bone calcium

86
Q

What is the role of CRH (corticotrophin-releasing hormone)?

A

Fetal lung maturation.

87
Q

Describe methods of avoiding unwanted pregnancies using birth control (contraception).

A
  1. Block sperm transport: Abstinence, condoms, barriers (diaphragm), sterilization (tubal ligation, vasectomy)
  2. Gamete suppression: Birth control pills (estrogen and progesterone) and birth control for men in the form of testosterone
  3. Block implantation: IUD, morning after pills (stops ovulation temporarily, prevents fertilization, prevents implantation, high doses of hormones)
88
Q

The adrenal gland stimulates the placenta to make ______. This creates a positive feedback loop.

A

pCRH. (Review slide 92)

89
Q

In the placenta, DHEAS is converted in the placental to _____, which together with placental prostaglandins and maternal oxytocin stimulate the maternal myometrium to undergo changes leaded to labour.

A

Estriol

90
Q

Increased receptors for oxytocin and prostaglandins and increased jap junctions in the myometrium lead to changes leading to ______.

A

Labour

91
Q

Positive feedback loop in birth: 1. Fetal adrenal gland secretes dehydroepiandrosterone sulphate (DHEAS) and cortisol upon stimulation by _________.

A

CRH and ACTH

92
Q

Positive feedback loop in birth: 2. Cortisol stimulates the placenta to secrete ____, producing a positive feedback loop.

A

CRH

93
Q

Positive feedback loop in birth: 3. DHEAS is converted by the placenta into a. ___, which together with prostaglandins and oxytocin stimulate the b. _______ of the mother’s uterus to undergo changes leading to labor.

A

A. Estriol
B. Myometrium

94
Q

How long does cervical dilation last in female humans?

A

8 hours

95
Q

How long does fetal expulsion taken in female women?

A

2 hours. Can take up to 10

96
Q

How long does fetal membrane expulsion take in female women?

A

1 hour or less

97
Q

How much time is required for the complete uterine involution of the female women after giving birth ?

A

40-45 days

98
Q

How much time is required for resumption of complete ovarian activity in female humans?

A

6-24 months

BIOM3200 (5 decks)

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