COLOR CODE FOR  P2M

                                                                                                Aug. 30, 2012

                                                                                                DHH interpretation

 

This wild type mid L1 larval hermaphrodite was prepared for Sulston and Horvitz for study of postembryonic cell fates in the early larval stages.  According to MRC notes, the animal was grown at 20oC, hatching at about 7 PM on the day of egg-laying, then fixed the next morning at 11:50 AM, when blast cells “V3 and V5 are in prophase”. A sister animal was fixed several hours earlier, when the Q2 daughters were still quite close together (I am guessing this may have been the animal now called “L1Q”). The original TEM prints for P2M were accompanied by a drawing of the layout of seam cell and ventral hypodermis positions as seen from a lateral aspect, and a series of quick sketches made by Nomarski imaging during the L1 animal’s development to show the relative positions of all nuclei seen from a lateral aspect, similar to the more polished drawings in Figure 4 of the paper.  By comparing the final sketch to the TEM series, Horvitz and Sulston could interpret the cell fates for known cell lineages.

 

The P2M animal is sectioned transversely, except that the tail tip is bending almost lengthwise.  The cell bodies of many epithelial cells are marked, including the lateral and ventral hypodermis, and the seam cells. 

 

See:  J.E. Sulston and H.R. Horvitz (1977) Post-embryonic cell lineages of the nematode Caenorhabditis elegans. Dev. Biol. 56: 110-156. 

 

According to the paper, EM images may have been prepared or annotated by Donna Albertson, Lois Edgar, John White, and Nichol Thomson.

 

Color code annotations follow the original MRC notes

 

Seam Cells marked as left / right pairs:

Left                  Right

1                      2                     

3                      4                     

5                      6         

7                      8         

9                      10

11                    12

13                    14

15                    16

 

Lateral Hypodermis marked as left / right pairs:

Left                  Right

7                      8

9                      10

11                    12

13                    14

15                    16

17                    18

19                    20

21                    22

23                    24

 

Ventral hypodermis

A         cell body has divided, but still joined by bridge

B         dividing

1

2

3

4

5

6

 

Central (mesodermal) cells

9

13

14

15        BWM

16

18

19

23

24        INT cell

 

left lateral cells

4

5

6

7

11

17

20

 

right lateral cells

1          phasmid  cell

3          phasmid cell

8          seam?

10        phasmid cell

12        PLM

21