Gonadolicious: A Review on Hermaphrodite Uterine and Vulval Development in C. elegans

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Gonadolicious A Review on Hermaphrodite Uterine
and Vulval Development in C. elegans

• Jadine Paw
• April 8, 2005

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Outline

• Basic introduction to anatomy
• Basics of Cell Lineage
• Germline
• Uterus Development
• Lineage
• Anatomy
• Vulva Development
• Lineage and anatomy

Note All information acquired from wormatlas,
Newman et al. (1996) and Sharma-Kishore et al.
(1999)
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Introduction

• Symmetrical, bilobed joined at uterus
• Somatic gonad (DTC, sheath, sp, sp-ut valve,
  uterus and vulva)
• Germline (meiotic and mitotic zones)

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Cell Lineage

• Founder cells
• Notation uppercase letter reveals lineage and
  lowercase letters that indicate division axis
  (ant, post left, right dors, vent)

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Gonad Lineage

• At hatching
• Germline from Z2 and Z3 (P4 lineage)
• Uterus and Vulva from Z1 and Z4 (MS)
• Vulva from Pn cells
• Note gonads are all developed post-embryonically
  (L1-L4)

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• By the L2/L3 molt, there are12 descendents
  (Somatic Primordium)
• Relative cell positions in the adult

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Distal Tip Cell and Tip
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• Arm Elongation acts as a leader cell

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• Control mitosis/ meiosis
• Maintains close germcells in mitotic stage
• Expresses ligand LAG-2, germcells express
  receptor. Activation blocks meiotic entry

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Germline

• From Z2 and Z3 (P4 lineage)
• Both sperm and oocytes must be produced
• Sperm is made during L4, and then only oocytes
  are produced during adulthood

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Germline Distal Tip

• Mitotic zone
• Syncitium

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Germline Transition Zone

• Germ cells in early meiotic prophase
• Nuclei appear crescent shaped

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Germline Loop

• Diplotene stage
• Oocytes start single file
• Note half of all oocytes are apoptotic, and most
  occur in this region

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Germline Proximal Arm

• Arrest here at diakinesis
• Oocyte maturation (enlargement, cytoplasmic
  contents) until ready to be fertilized

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Spermatheca

• 24 cells (from SS and DU)
• All sperm made in L4
• Made in oviduct and pushed into spermatheca when
  1st oocyte released
• Before oocyte passes, it is narrow and folded
• Made in L4 but not mature

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Oocyte is fertilized as it passes through the
spermatheca, and then it develops in the uterus
(develops to 100 cell stage, 2.5 hrs after fert.)
and then expelled through the vulva
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Uterus Development

• Begins in L2
• By end of L4, development is complete
• Uterine cells clearest (embryos distort and crowd
  shape)

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Uterus Anatomy

• 2 symmetrical lobes
• 4 ut - uterine toroid epithelial syncitia
• UT1, UT2, UT3 4 nuclei UT4 6 nuclei
• Joined to each other through adherens junctions
• du dorsal uterine cell (4 nuclei syncitium)
• caps dorsally

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Uterus Anatomy Cont

• utse uterine seam cell
• H-shaped, 9 nuclei syncitium
• Attaches uterus to seam to keep it in shape and
  in place
• uv 1-3 uterine vulval cell
• Connects uterus to vulva

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Uterus Development
Divide into cells of the uterus
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Uterus Cell Divisions

• uterus made of 60 of 84 descendents of the 2 DU
  and 3 VU cells.
• DU (48)
• 28 for uterine tissue
• 12 to spermatheca
• 8 to ut-sp junction
• VU (36)
• 32 to uterus
• 4 to ut-sp junction

Divide into cells of the uterus
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A Dorsal and Ventral Side
undergo 5 rounds division
undergo 4 rounds division
L2 After somatic primordium is established into
DORSAL and VENTRAL rows, the signaling between 2
equivalent cells results in ONE adopting the
IMPORTANT anchor cell (AC) role. The other
becomes a vu cell.
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• Importance of AC
• AC induces 6 VU great grandprogeny to p
• TWO rows of p (dors/vent)
• required for egg laying and to contact vulva
• will become utse and uv1
• Others VUs adopt ?
• will develop to ut toroids and ut-sp valve
• differences between the 2 fates are and
  morphology of progeny, axes of division

2 divisions later
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Dorsal
Ventral
Another round of division
Cells are in position and do not change much
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migration
Each ut toroid made of 2 DU and 2 VU descendents
Blue ut toroids (? 4 or 6 nuclei) Red utse
(9 nuclei) and uv1 (1 nuclei) (p) Yellow uv2
and uv3 (DU 1 nuclei each)
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Taking Shape
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6-7.5 hrs into L4, migrating cells are in place
6-7.5 hrs, migrating nuclei reach final locations

• Lumen formation between dors. vent.
• uv1 connects to vulF
• Utse contacts vulval lumen
• Vulval lumen formation

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Final Development
(ut)
(4)
(8)
(9)
uv1 extends processes to contact vulva cells
(adherens junctions) and utse connects to seam
cell and vulval lumem
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Vulva Anatomy

• Made of 7 epithelial rings/ toroids
• Joined to each other via adherens junctions
• Each made of a tetranucleate syncitium or 2
  binucleate half ring syncitia
• All progeny of ventral hypodermal cells Pn.p
  (born in L1)
• Same development time as uterus (L3 L4)
• Require AC, like the uterus

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Vulval Development

• Execution and Short-range Migration
• 22 epithelial cells made and migrate to make the
  7 rings
• Cell fusions (during most of L4)
• 7 rings fuse
• Vulval muscles attach
• Eversion
• Vulva turns inside out (L4/ adult molt)
• Lumen closes to block transit of eggs

In 20 hrs?
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Vulva Cell Lineage

• L1 12 ventral hypodermal cells generated
• P(1-2).p and P(9-11).p fuse to Hyp7
• P(3-8).p become the Vulval Precursor Cells (VPC)
  all have potential
• Ultimately P(5-7).p selected
• P(3, 4, 8) to Hyp7

P5.p, P6.p and P7.p given vulva potential
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Vulva Cell Lineage

• Due to AC (Lin-3/Let-23 Map kinase pathway)
  lateral signaling between VPCs and hyp7
• Cells put into position

vulA-D
vulE/F
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AC
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• Short-range migrations from outer to inner
  regions
• migrate to reach the same partner on other side
• begins with vulF in a temporal sequence

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Short-Range Migrations

• A 34 hrs, 22 vulval cells
• B 35 hrs, vulD migrate to surround inner ring
• C 36 hrs, outermost cells begin to send
  processes out
• D 37 hrs, vulC fusion
• AC black dot in middle

Note as the cells migrate towards the center,
the apex is pushed dorsally (lumen formation)
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Lumen Formation

• Invagination
• 1 and some 2 cells detach from cuticle and
  rearrange cell contacts
• Forms vulval lumen

• Lumen connections
• AC penetrates vulF, attaching it to ut1 of
  uterus (adherens junctions), then fuses with the
  utse

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Ring Fusions

• Order of fusions vulD, A, C, F, E.
• (vulB1 and B2 do not fuse)
• Also
• vulE attaches to seam cells (prevents collapse),
  VC and HSNs vulA to hyp7
• Muscle attachments (vm1 and vm2, 4 each)
  throughout
• vulF attaches to 4 uv1

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Final Stage Eversion
Late L4, after muscle attachments the vulva
everts to generate the adult vulva. This closes
the lumen, which will not open until muscles
contract.
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