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004 - Reproductive Biology > 02 - The Indifferent Gonads > Flashcards

02 - The Indifferent Gonads Flashcards

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1
Q

(The indifferent gonads)

1-3. During embryonic development 3 sets of kidneys develop sequentially… name them

A
  1. pronephros
  2. mesonephros
  3. metanephros
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2
Q

(3 Sets of Kidney)

(say what happens to each)

  1. pronephros
  2. mesonephros
  3. metanephros
A
  1. degenerates - duct persists as mesonephric duct
  2. contains tubules induced to form by residual mesonephric duc. also degenerates except for some of the caudal tubules (and the mesonephric duct)
  3. develop into kidney and ureter
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3
Q
  1. The gonads develop from what?
  2. In both sexes this mesenchyme is invaded by what? which (along with cells from degenerating mesonephric tubule) form what?
  3. the stage of the undifferentiated gonad is prolonged in males or females?
A
  1. the urogenital ridge (a strip of mesenchyme adjacent to the ventromedial surface of the mesonephric kidney)
  2. coelemic mesothelial (epithelial) cells; the cellular cord of the indifferent gonad (The first proliferation of the sex cords)
  3. females
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4
Q

(In the final gonads there are 4 cell lines)

(3 somatic cell lineages)

1-3. name them (plus give male/female names)

(1 germ cell lineage)

  1. name it (male/female)
A
  1. supporting cells (Sertoli/follicular granulosa) (these are crucial)
  2. steroid-producing cells (Leydig/theca)
  3. mesenchymal cells (paeritubular myoid cells and vasculature of testis, connective tissue and vasculature of ovary)
  4. spermatogonia/oogonia
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5
Q
  1. each cell type that makes up the indifferent gonad can
    potentially differentiate down either a female or male line. For this reason the indifferent gonads
    are also termed what?
A
  1. bipotential gonads
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6
Q
  1. The fate of biptotential gonads as testicles or ovaries is decided by the fate of what? this battle is essentially waged by what?
  2. Which sex is Sox9 and fibroblast growth factor 9 (Fgf9)?
  3. which sex is Wnt-4, R-spondin1 (RSPO1) and FOXL2?
  4. what is the funtion of Sry in all of this?
A
  1. supporting cells (sertoli vs. granulosa); 2 competing genetic cascades
  2. male
  3. female
  4. gets Sox9 going before female starts
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7
Q

(Differentionat of the gonads)

  1. in lower animals the indifferent gonad has 2 distinct regions: what are they?
  2. cortex differentiates into what?
  3. medulla?
A
  1. cortex and medulla
  2. ovary
  3. testicle

(similar, if less defined, arrangement occurs in males)

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8
Q

(Differentiation of the Testicle)

  1. Do embryonic female or male mice grow faster?
  2. why might this be?
A
  1. male
  2. unknown… but may be that males must rapidly get to stage of gonadal determination to avoid being involved in the female pathway
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9
Q
  1. The earliest noted change during sex determination is a doubling in the size of the gonad in XY embryos… what is this due to?
  2. This proliferation is required for formation of what?
  3. What percentage of cells must be Sry expressing Sertolli cells for testicle (not ovary) to result?
A
  1. massive proliferation of pre-Sertolli cells directed by Sry
  2. the testicle (and inhibit ovarian development)
  3. >30%
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10
Q
  1. Is expression of Sry in pre-Sertoli cells constant or transient?
  2. The protein product of Sry working together with Sf-1 results in what?
  3. What is the critical step to cause differention of supporting cells into sertoli cells?
A
  1. transient
  2. up-regulation of Sox9 (which is then continually expressed)
  3. up-regulatino and continued expression of Sox9
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11
Q

(Differentiation of the testicle)

  1. the fact that only 30% of supporting cells need to express Sry implies what?
  2. newly differentiated Sertoli cells rapidly aggregate to form what?
  3. Is formation of a hormonally functional testicle dependent on presence of germ cells?
A
  1. that paracrine signals from these cells can recruit other supporting cells to the supporting cell pathway
  2. the testis cords (male specific “second proliferation of the cords”)
  3. no
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12
Q

(Differentiation of the testicle)

(A further proliferation then occurs in other, non-Sertoli cell lines and these cells are recruited to the male pathway by the Sertoli cells using cell-cell interactions)

  1. Leydig cells are induced to proliferate by what? partitioned to the what?
  2. In males, myoid cells migrate into the genital ridge from what and surround what? what do these cells separate?
  3. The germ cells are drawn into what? and then into what?
A
  1. fetal Sertoli cells; interstitium (outside the cords)
  2. from the mesonephros and surround the cords (perhaps participating with Sertolli cells in development); Sertoli and Leydig cells
  3. drawn into medulla and then into sex cords (which then become prominent)
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13
Q

(Differentiation of the Ovary)

  1. what called when female germ cell is dividing by mitosis (numbers increasing)

when finished this stage they become

  1. female germ cell that has entered meiosis (dividing to bcome haploid… no increase in numbers)
A
  1. oogonia
  2. oocyte
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14
Q

(Differentiation of the Ovary)

  1. Are germ cells required for formation of normal ovary?
  2. What fail to develop in absence of oocytes? What happens to supporting cells? what is formed?
A
  1. yes (unlike testes)
  2. ovarian follicles; they degenerate; “streak gonad”
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15
Q

just read page 9

A
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16
Q

(Origin, migration, multiplication and fate of the Primordial Germ Cells)

  1. What is origin of primordial germ cells? under the incfluence of what?
  2. These cells migrate intwo what where they begin proliferating? then migrate through what to where via amoeboid type movements?
A
  1. primitive ectodermal cells of the inner cell mass (epiblast); bone morphogenic protein (BMP)
  2. the dorsal yolk sac endoderm; hindgut epithelium and mesenteries –> ventral mesonephros –> gonad

(Control mechanisms for this migration are still being explored but involve alterations in cell adhesion molecules, and a path defined by combinations of attractant and repulsive signals (which probably change in different areas of the migration pathway).)

17
Q

(Origin, migration, multiplication and fate of the Primordial Germ Cells)

  1. At the end of their migration, where do primordial germ cells become concentrated in females? in males?
  2. Why does migration probably cease?
A
  1. cortical region; medulla
  2. cells have reached highest concentration of attractant
18
Q

(Origin, migration, multiplication and fate of the Primordial Germ Cells)

  1. How many germ cells at beginning of migration? how many when they enter the genital ridge four days later?
  2. Is there further division in the gonad?
  3. After proliferation, followed by what?
  4. Will have some oogonia have entered the first meiotic division during the multiplication phase in the gonad?
  5. Soon after birth and the wave of atresia, all remaining germ cells in the ovary will be what?
A
  1. few (8-70); many (2,600-5,700)
  2. yes (vigorous)

(in human female (3-5 weeks = few hundred) (600,00 = eigth week) (7 million = fifth month)

  1. atresia
  2. yes (leading to the formation of primary oocytes)
  3. primary oocytes arrested in the first meiotic prophase
19
Q

((Origin, migration, multiplication and fate of the Primordial Germ Cells))

(A similar multiplication phase occurs in the developing testes)

  1. However, in males when does meiosis commence?
  2. What are the germ cells of the male fetus doing when the female germ cells are entering meiosis (13-15 dpc in mice)
A
  1. puberty
  2. entering mitotic arrest as prospermatogonia (resume mitotic proliferation post-natally)
20
Q

(Germ-cell Sex Determination: Mitosis vs. Meiosis)

  1. Primordial germ cells sometime smigrate to extragonadal sites… usually what or what?
  2. Irrespective of the sex of the embryo, all germ cells at these non-gonadal sites differentiate as what? When do they enter meiosis relative to the oocytes in the ovary?
  3. What happens to these ectopic (abnormal) cells? why?
  4. Thus… all germ cells are potentially female regardeless of their genetic sex… unless what happens?
  5. The reverse occurs in seminiferous cords of the testes… what happens here?
A
  1. the adrenals or kidneys
  2. oocytes (both XX and XY primordial cells); at the same stage
  3. degenerate; absence of supporting (follicle) cells

(a similar fate awaits those in ovary that fail to become surrounded by supporting cells to form a follicle)

  1. they migrate to a developing testis and are enclosed in seminiferous cords
  2. both XX and XY will enter mitotic arrest and develop as T-spermtogonia
21
Q

(Germ-cell Sex Determination: Mitosis vs. Meiosis)

  1. The fate of germ cells to continue mitosis (testis) or enter meiosis (ovary) is determined by….
  2. what that prevents entry into meiosis
  3. what which promotes it
A
  1. Fgf9
  2. retinoic acid (RA, vitamin A derivative)
22
Q
  1. Does whether the primordial germ cells develop into oocytes or spermatogonia depend on the gonadal environment or on genetic makeup?
A
  1. their gonadal environment

(However, their genetic sex does significantly impact their fate during subsequent oogenesis or spermatogenesis)

23
Q

(However, their genetic sex does significantly impact their fate during subsequent oogenesis or spermatogenesis)

  1. presence of only one X chromosome in oogonia causes what in regards to oocytes?
  2. XO (Turners) and (XY) sex-reversed females have number number or oocytes in what?

What does this lead to in mice?

in humans?

why?

A
  1. causes a reduction in oocyte survival during meiosis
  2. post-natal ovary

reduced reproductive lifespan

sterility

longer time between birth and puberty (more losses)

24
Q

(However, their genetic sex does significantly impact their fate during subsequent oogenesis or spermatogenesis)

  1. Presence of XX chromosomes in germ cells of testicle result in what?
  2. The germ cells fail to progress past what?
  3. What is this due to?
A
  1. infertility
  2. beyond prospermatogonia (and degenerate when mitosis resumes after birth)
  3. lack of Y spermatogenesis genes - and too much X

004 - Reproductive Biology (30 decks)

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