There are two kinds of pedigree display. The Cell pedigree tree (located on the Cell Page) or the Lineage pedigree tree (located on the Pedigree Browser). The Cell Page is simple and easy to use, with a full description of the cell lay out, while the advantage of the Pedigree Browser is that it displays complete lineage pathways (from P0) with user-interested cell(s) highlighted.
Starting from the Search on the WormBase home page. Select from the pull-down menu "Cell" and enter the cell name. A "cell summary" display will appear with a Cell pedigree display box showing three generations of cells. Your cell will appear red on the pedigree. Users can move the pedigree tree up or down in the lineage by clicking on the parent cell or daughter cells. Another way to access pedigree is from "Cell and Pedigree Search" (under More Searches menu), which searches for specific cells, cell groups, or lineages.
There is a very good article explaining everything about embryonic cell lineage and nomenclature:
Sulston JE et al (1983) Dev Biol. "The embryonic cell lineage of the nematode C. elegans."
That article is the standard reference on C. elegans cell nomenclature.
P0 is the founder cell for C. elegans. It is the zygote after fertilization. The first few rounds of divisions produce six "founder cells": E, MS, AB, C, D and P4. Each of these founder cells generate different tissues. From then on, cells are named after these founder cells. For example, the daughters of AB are called ABa ('a' means anterior) and ABp ('p' means posterior). ABa will generate daughters ABal ('l' means left) and ABar ('r' means right)... If cell divides dorsal-ventrally, 'd' or 'v' will be added to the name of daughters.
Now you know when you see ABalppp , it comes from:
P0->AB->ABa->ABal->ABalp->ABalpp->ABalppp
Not only will you see the lineage pathway from the cell name, you will also see in which direction cells have divided and what the sister cells are for each step of the division.
Most of the information you need for a cell should be contained on Cell Report, which can be located by "Cell and Pedigree" search. In WormBase, if you read the Tree Display of a Cell Report, there is a tag called "Embryo_division_time"; it is the time when the cell divides or dies. Unfortunately, for cells generated after hatch, there is no such information in WormBase.
There are two sets of P cells. One arises from early embryonic divisions, and are called P0, P1', P2', P3' ... in WormBase; these are the lineage names. The other set is called P1, P2, P3, ... These are postembryonic blast cells, which are not related to the embryonic founder cells.
P1, P2, P3.. are adult names for post embryonic blast cells preset from hatching until the middle of the first lalval stage (L1), . A lot of cells have two names: lineage name and adult name. Adult name is the name people give to some cells that become terminal and differentiate (such as neurons) or not differentiate but will divide into an important lineage (such as P1, P2 ... lineages). Adult names are given by cell position and function, so it is a different naming system. Cells with the same adult name could come from different lineages depending on how bilateral symmetry is broken, for example: P7 can be developed either from AB.plappapp or AB.prappapp.
Lineage name is accurate, unique, but hard to remember for most people, so adult names are usually for researchers to use and do the query. That is why in WormBase cell nomenclature, whenever there exists adult name, we use it to call a cell, and bury its lineage name inside data field.
When we curate a gene, we enter all the cells and cell groups that express the gene. This information can be easily viewed by clicking the "details" button at the gene page. For example, if you search for eat-16, which is expressed in neurons:
1. At the WormBase home page, select "Any gene" and search for "eat-16", and select "Exact Match", this will take you to the Gene Summary page for eat-16. 2. In the Function section, you will see "Anatomimic Expression Pattern". Here you will see some information about the eat-16 expression pattern, at the very end of the entry, you will see a link "Details". 3. If you click here, you will be brought to the Expression Pattern page for eat-16. On this page you will see the detailed cell and cell group information associated with eat-16. (To keep annotation easy, when a gene is expressed in lots of cells, we enter cell group name instead of all the cell names one by one. Each cell group will include the list of cells associated.)
This is availabele on the WormClassroom website.