Human Fetal Development - Part 1

The most enjoyable blogs for me are the ones with no real theme other than a general one, just whatever comes into the mind of the writer.  If I manage to get a thought in my head, it is like a pinball in a Black Rose arcade game.  This past week, I was thinking about embryo development and how complicated that is.  Bovine embryo development, I am familiar with but human, not so much.  Sure, we had four kids but it was kind of like bowling through a blanket; no idea what was happening after the initial roll, so to speak.

DNA is kind of magical stuff. Data is stored in binary format, surprisingly enough. There is roughly one CD worth of data in the human genome; all crammed into a cell nucleus about 6 one-thousandths of a millimeter in diameter. DNA is organized into genes which makes you what you are.  Not just the physical (some of which is also normally binary such as male or female plumbing) but also the unseen stuff like personality, sexuality, intelligence, humour. . . How you respond to your environment is hard wired into you, as we are all both nature and nurture. The more we learn, though, the more nature seems to have the upper hand in so many things.

DNA contains not only the information for your physical and mental self, it also contains the information that turns the various genes on and off when and where appropriate so you are not just one huge blob of identical cells, like yeast or something (Stifle, Edith). The vast majority of this happens during the first few weeks of embryo development (bovine and human).  There is a great deal that can go wrong during that time and estimates are that only 30% of fertilized human eggs result in a live birth (with cattle, it is 70%). The majority of spontaneous abortions or miscarriages have chromosomal abnormalities. The causes of most congenital abnormalities are unknown.

A quick review of ordinary cell division from highschool biology: (Click on pictures to enlarge)

https://lookfordiagnosis.com/mesh_info.php?term=mitosis&lang=1#

The following videos are simple enough even for me to understand and should be watched in the order listed if you are serious about all this.  Number 5 is optional unless you are really serious.

1. Video explaining Cell Structure (7:21) https://youtu.be/URUJD5NEXC8
2. Video explaining DNA to protein (2:42) https://youtu.be/gG7uCskUOrA
3. Video explaining how DNA is replicated (3:27) https://youtu.be/TNKWgcFPHqw
4. Video explaining Mitosis (6:10) https://youtu.be/C6hn3sA0ip0
5. Video explaining DNA structure (5:57) https://youtu.be/o_-6JXLYS-k

When I count days or weeks in this blog post, it is from the time of fertilization of the egg.  Some of the references I ran into counted from the date of the end of the woman’s last period which is confusing as ovulation/fertilization usually occurs about 10-12 days after that so why not start there?

All the cell contents and half the chromosomes are in the egg.  Sperm is not much more than half the chromosomes with a tail.  Relative size is sort of like a rocket ship circling the moon.  Millions of sperm are released but only one enters the membrane of the egg. The reason it takes millions of sperm is that being male, they do not ask directions and most get lost enroute. Once a sperm cell has entered the egg, the membrane becomes impermeable to all other sperm.

Adapted from www.eevatest.com/sites/eevatest.com/files/embry-dev-stage.png

Adapted from dev.biologists.org/content/139/5/829

On Day 1, the pronuclei of the sperm and egg unite to form a nucleus with a full complement of chromosomes at which point the egg becomes a zygote, about the size of a grain of salt, a stage which lasts about 14 days.  One day 1, the single cell becomes two cells.  On Day 2, the two cells divide again becoming 4 cells and by Day 3 it becomes 8 cells.  

By this time the genetic function that was egg-oriented (egg mRNAs decrease) has pretty much wound down and genetic functions reprogrammed to development mode (development mRNAs increase). The overall size of the zygote does not change as more cells are added.  The membrane of the egg becomes the protective membrane (zona pellucida) of the zygote up to Day 6 when the blastocyst hatches and is ready to implant on the uterine wall on Day 7 to 12*.

* For detailed pre-implantation development, see dev.biologists.org/content/139/5/829

And sadness cut through me. . .

Many of the poems I learned in school are still with me, at least the first and usually more lines.  Hard to say why other than I liked or loved the poem. Everything from Walter de la Mare's 'Someone Came Knocking' and 'Silver'; William Wilfred Campbell's 'Indian Summer';  or Bliss Carmen's Vestigia.  Kipling, Tennyson, Browning, Noyes were all favourite authors, along with Coleridge, Longfellow, Hardy, Elliot, and many more.

CT Fyfe's anthology 'A Book of Good Poems' was one of my grade 11 and 12 Literature books.  My teacher, the late Sister Mary Annella (Pek), had Fyfe as her prof at University and she loved poetry as did I.  I had two copies which my children now have though I wish I had one of them back. Two of the poems I love to read when ever I am sad and do not want to play 'hurtin' music'.

Both poems leave the reader hanging as to who, why, and what happened which adds to the melancholy. The wordsmithing is incredibly beautiful.  I hope you enjoy them.

The Listeners Walter de la Mare

"Is there anybody there?" said the Traveller,
Knocking on the moonlit door;
And his horse in the silence champed the grasses
Of the forest's ferny floor:
And a bird flew up out of the turret,
Above the Traveller's head:
And he smote upon the door again a second time;
"Is there anybody there?" he said.
But no one descended to the Traveller;
No head from the leaf-fringed sill
Leaned over and looked into his grey eyes,
Where he stood perplexed and still.
But only a host of phantom listeners
That dwelt in the lone house then
Stood listening in the quiet of the moonlight
To that voice from the world of men:
Stood thronging the faint moonbeams on the dark stair,
That goes down to the empty hall,
Hearkening in an air stirred and shaken
By the lonely Traveller's call.
And he felt in his heart their strangeness,
Their stillness answering his cry,
While his horse moved, cropping the dark turf,
'Neath the starred and leafy sky;
For he suddenly smote on the door, even
Louder, and lifted his head:--
"Tell them I came, and no one answered,
That I kept my word," he said.
Never the least stir made the listeners,
Though every word he spake
Fell echoing through the shadowiness of the still house
From the one man left awake:
Ay, they heard his foot upon the stirrup,
And the sound of iron on stone,
And how the silence surged softly backward,
When the plunging hoofs were gone.

Beyond The Last Lamp By Thomas Hardy (Near Tooting Common)

I

While rain, with eve in partnership,
Descended darkly, drip, drip, drip,
Beyond the last lone lamp I passed
Walking slowly, whispering sadly,
Two linked loiterers, wan, downcast:
Some heavy thought constrained each face,
And blinded them to time and place.

II

The pair seemed lovers, yet absorbed
In mental scenes no longer orbed
By love's young rays. Each countenance
As it slowly, as it sadly
Caught the lamplight's yellow glance
Held in suspense a misery
At things which had been or might be.

III

When I retrod that watery way
Some hours beyond the droop of day,
Still I found pacing there the twain
Just as slowly, just as sadly,
Heedless of the night and rain.
One could but wonder who they were
And what wild woe detained them there.

IV

Though thirty years of blur and blot
Have slid since I beheld that spot,
And saw in curious converse there
Moving slowly, moving sadly
That mysterious tragic pair,
Its olden look may linger on -
All but the couple; they have gone.

V

Whither? Who knows, indeed . . . And yet
To me, when nights are weird and wet,
Without those comrades there at tryst
Creeping slowly, creeping sadly,
That lone lane does not exist.
There they seem brooding on their pain,
And will, while such a lane remain.

Free at Last or a Lazy Day With No Guilt

Yesterday, I finished a report that had been hanging over my head for a long time.  I put a real push on it last week or so which is why I have not read any blogs nor written any.  If I am at the computer, I needed to work, I told myself.

Mostly the report was trend analysis of agriculture and livestock production over 15 years.

• 1 country
• 1 state
• 2 counties, 
• 20 municipalities
• 4 species of livestock 
• 4 livestock products
• 20 field crops - area and production
• 10 fodder crops - area and production
• 40 vegetables - area and production
• 30 fruits and nuts - area and production
• 2 main sources of data which did not always agree
• 2 sub-sources whose data did not always agree from year to year

Do the math, I am tired of it, but it comes to millions of numbers, I expect.  Feels like it anyhow.  Boiled it down to 185 pages, 100 tables and 150 figures.  Tomorrow I talk to the client.

100 tables, many larger, a few smaller

150 figures, many more complex than this

Now I can go and catch up on my blog reading.

We have been out of Scotch for two weeks but I can live with that.  The last of the coffee went this morning.  I will likely die.

News Depresses Me, Baby Goats are Better

Some people eat to live; others live to eat.  I live to know, to absorb as much as I can about the past and present of countries and cultures that interest me.  To try to understand what and why.  So I read history books and news on the internet. European and in particular Russian history and news items about Russia, Ukraine, Turkey in particular (with related items on Syria, Poland, EU, Greece) and America, Canada too .  Every day, maybe 50 to 150 news items specifically related to my interests cross my screen via email links or Facebook links.  I can't read them all but I scan most of the headlines and read at least 25, wishing I could read them all. But my head won't let me.

Russian history is never an easy read.  Anne Applebaum's Gulag: a history is just one of many books dealing with the unspeakable crimes committed during Soviet times. David Satter's It Was a Long Time Ago, and It Never Happened Anyway: Russia and the Communist Past explores Russia's inability/refusal to deal with its past and therefore its continuation down the same pathway today under Putin. Is there ever to be a future for the Russian people different from their past?

Ukrainian/Russian news is singularly depressing and why I have not blogged about it lately. Day after day the stories are the same.  the names and places change but not much more.

This article will give you a feel for the Russian stories.

Chechnya turns into terror zone as another Russian human rights defender attacked

And this one for the Ukrainian stories.
Behind the scenes of civic society’s battle with corruption in Ukraine

Then when I read that the EU is pressuring Ukraine to implement Minsk unilaterally (the way Russia wants it) so they can drop sanctions and get on with business as usual and that Obama says Ukraine is a client state of Russia, I just despair.

Knowing and understanding what little I have over the years has brought me no peace. Today is St Patrick's Day.  I think I will finish off my bottle of Jamison and watch baby goats.

Goats playing

Pizza and Cinnamon Buns

The flower gardens were dry enough to walk on and spring bulbs are already a couple inches high, with small brave blooms on snowdrops and crocuses. The girls were here today, Lina and Sveta, helping Tanya clean up her flower beds.  We gave them taxi fare and sent them home with one of Tanya's home-made pizzas and a tub of my home-made pork and beans.  The girls aren't easy but they can be bought.

Tanya has a  yeast raised dough recipe she uses for pirog (pie, stuffed with eg cooked cabbage and then fried) and lavash (like pirog but no stuffing).  We discovered it makes a wonderful pizza crust and have been churning out pizzas ever since.  Topping as pretty much the same - tomato sauce, various sausage, peppers, tomato slices, dill pickle, mushrooms, green onions, what ever we have, and grated local cheese.  Herbs and spices for pizza I need to look up on the internet because I make it up as I go. Oregano, for sure.  I put that on anything I can get away with.  Garlic salt (too lazy to use fresh garlic, though we have done that too.  Something called Italian spice mix but no idea what it is.  Dried chili peppers in limited amounts.

Usually if I help we make eight at a time but today, Tanya made four only. She left enough dough for me to try cinnamon buns for the first time.  Not perfect but certainly not a failure.  They were pronounced delicious.  The dough makes a very light bun so it is not an ordinary bread dough recipe, I know that.  Next time I will make a full tray.

Glassware is short lived at our home, it seems.  To have a pair of matching glass tea mugs, you need to start off with six. Concrete floors covered in ceramic tile are  unforgiving and the cups are in constant use.  We were getting low. A glass water jug had also gone the way of all flesh (or something) so I stopped in at our favourite kitchen store.  Bought a plain jug; was offered a fancy one for twice the price but thought better not. Also bought four lovely glass tea mugs with lilies on them.

He had six but it was pay for them and walk home or take four and a taxi.  I opted for the taxi and suggested Tanya stop in on her way home next day and pick up the remaining two.  She said she was afraid to go into that store.  I understood that as it is an easy place to spend money.  She did well, though.  Bought the two mugs and only two quite nice decanters which cost $2 each.  I would put oil and vinegar in them but vinegar isn't a thing in Ukraine like it is in Canada for salad dressings.

Information you will never need

Health care in Ukraine is free by the constitution.  It is illegal to pay a doctor or nurse at a state hospital or clinic.  However the state then steals all the money and pays them at Soviet rates of less than $70 per month, which of course they cannot live on.  So they require 'gifts' in appreciation for their services, which is only fair.  Some angry young doctor is taking the state to court to force them to either change the law or pay proper wages.

There are also private clinics with well trained specialists and modern equipment, for which you pay. Last week, I went to see my heart specialist at ProfiMed Clinic.  Not sure if the profi is profit or professional, not that it matters.  ProfiMed have a number of specialists on staff, do blood work and also some out-patient stuff.

Tanya comes in with me and since she knows me better than I know myself, converses with the doctor and fills me in after.  My blood pressure was 150/80 or something.  Not good enough so I am on one more pill of some kind, come back in a month.  My heart rate however surprised her.  "How can you have high blood pressure with a heat rate about 45-55?" "Elephants have much lower heart rates than smaller mammals" which made them laugh.

And which brings me to today's lecture, boys and girls. How do you compare the heart rates of mice and elephants? The answer is a variant of Kleiber's Law on the relationship between body mass and metabolic rate.

Metabolic rate is, in simple terms, measurable in calories (or joules*), the amount of heat lost per unit of time by the body of an animal. We know that large animals need more energy to survive than small animals but how much more?  A 4 tonne elephant is 160,000 times larger than a 25 gram mouse.  But it does not need 160,000 time more food in a day.  Bigger animals use food more efficiently than small animals.

Heat loss is a function of surface area. Heat production is a function of body mass.  Thing of an animal as a sphere.  Surface area is a function of the radius squared (r²).  Body mass, on the other hand is the volume of the sphere which is a function of the radius cubed (r³).  So there is some argument that Metabolic Rate varies with Body Mass to the two-thirds power (MR∝W_kg^2/3).  But 2/3 is not quite right.  

Max Kleiber, sometime in the 1930's, determined that a more accurate formula was Metabolic Rate varies with Body Mass to the three-quarter power (MR∝W_kg^¾).  This is simple.  Multiply the body weight in kg (or lb) by itself three times, then take the square root twice.  Any calculator can do it. 

The formula for heart rate** or pulse (P or bpm) is a little trickier to understand but simpler to do. P≈186*W^-1/4.  An easier way to write it so it can actually be calculated is P≈ 186*(1/W^1/4). Something to the ¼ power just means take the square root twice.

Mouse – 25 grams – calculated heart rate 465

Cat – 2.5 kg – calculated heart rate 148

Human – 100 kg – calculated heart rate 59

Elephant – 4000 kg – calculated heart rate 23

Obviously these are ballpark as individual heart rates vary widely, even in an acceptable range but it does illustrate my point.  Elephants have lower heart rates than smaller mammals.

Thus endeth today’s lesson.  

*Would you refer to the week's groceries as the 'family joules'?
**My thanks to my friend and mentor, Professor Emeritus Dr D.A. Christensen, U of S, for sending me photocopies of pages from Kleiber's timeless book, "The Fire of Life"

The Sewing Machine

Tanya had been talking about getting a sewing machine for years.  So today I put a gun to her head and made her buy one.  Told her I would pay and call it her Valentine's Day and International Woman's Day gift.

She has been worried that it would be too complicated for her but the two women at Comfy found her the Minerva Classic which has 12 functions only.  Tanya said her grandmother's only had one function and it did everything so 12 would suit her fine.

The price was very reasonable but across the aisle were cappuccino machines.  I said, "3000 Hrivna for a sewing machine and 30,000 Hrivna for a coffee maker?'

"Yes", Tanya said, "But one is for work, the other for pleasure".

There must be a lesson in there somewhere.  It is a great straight line.