When you teach cell biology over and over again you end up looking at a lot of textbook figures showing the inside of the cell, and that has a stupidizing effect. Everything is so present and accounted for; the endoplasmic reticulum blooms out of the nuclear membrane, the Golgi body between the ER and the plasma membrane, mitochondria, ribosomes and vesicles swim around in the cytoplasm. Each textbook figure, while slightly different to avoid the copyright of the last cytoplasmic artist, is just like the last and the next. Rarely do you learn anything new by looking at these pictures. Enter the annulate lamellae.
I stumbled upoon it in papers describing the neoblast cells of Planarian worms (here) while reading up on why my students would have THREE Planaria in a dish resulting from cutting ONE worm in half three weeks ago. Some of these cells are described as having no ER (what??) and sometimes the ER that is seen is
“apparently detaching from the nuclear to move out into the cytoplasm”
I’m sorry, what?
I realize how little I actually know about the dynamics of the ER. Every picture of every cell I have ever seen just had one, but those were pretty much all cartoons, which apparently are not real life. But this is just the observation of one author from 1969 – back before they invented restriction enzymes, so what the hell could they possibly know?
Annulate lamellae are described in the same breath as the ER that is divorcing the nuclear membrane and I can’t tell if they are a subset of the ER or a completely different thing. Are these a thing that people still study? I have come across cool tidbits like this before that end up being the one time mentions, never to be described again, so I search Pubmed for “annulate lamellae” and whoa:
169 papers come up, second to the last one being a 2015 PLOS One paper claiming that AL have nuclear pore complexes in them, despite being little islands in the cytoplasm (I’m sorry, repeat that again?). A Google search gives a decent “about 22,300” hits showing that they have been found in human oocytes, sperm, tumor cells, yeast cells. However it does not have an entry in Wikipedia and thus does not officially exist.
All of this only shows how small my brain is, my capacity to forget what I “learned” as an undergrad, or my lazy habit of relying on textbooks, or all three. It certainly leaves me grateful to Johns Hopkins for access to full text PDFs of articles from ye oldde tymes. Can’t wait to hit my human-disease-centric grad students with a paper about a flatworm cells this summer 🙂