Embryo Story

THE BEGINNING:

oocyte - zygote - cleavage - morula – blastocyst - blastosphere - gastrula

‘Thanks to von Baer and his followers, biologists by the early decades of the 20th century could describe in fine detail how embryos originate and unfold. Each begins with the fusion of a female egg (oocyte) with a male sperm – which is the act of conception – to form a single-celled embryo (zygote). The zygote then divides – division is called cleavage – and divides again to form a ball of cells, knows as a morula, which grows and divides further to form a blastocyst. The individual cells within a morula or blastocyst are called blastomeres. Many mammalian embryos, including those of humans and mice, become embedded or ‘implant’ in the wall of their mother’s uterus at the blastocyst stage; but those of ruminants, including sheep and cattle, do not until the fourth week after conception…As division proceeds further the blastocysts typically becomes hollowed out to from a blastosphere or blastula. The blastula then fold in upon itself – this is often compared to a tennis ball being pressed in – to form a multilayered but still basically spherical entity now called a gastrula. It is as the gastrula stage that the embryo truly begins to mould itself into the form of the creature it is to become. The whole structure becomes more complicate as the newly formed, discrete cell layers start to slide over each other and fold in upon themselves ina supremely choreographed and self mobilising exercise in origami. At the same time, different groups of cells in different parts of the embryo can be seen to diffentiate, giving rise to daughter cells that are different from themselves and assuming the structure and function of specialist cells in specialist organs – liver, lung, brain, intestine, muscle, and the rest. The transformations from single cell to ball of cells to hollow ball to apparently self-forming creature are intricate, swift and usually unerring – although not without diversion…Altogether the whole unfolding is stunning. No wonder so many biologists have been drawn to embryology.’ Ian Wilmut, Keith Campbell, Colin Tudge, The Second Creation, Headline, 2001

Oocyte - zygote - cleavage - morula – blastocyst - blastosphere - gastrula

are the first steps of the primary movement, 

after silent overtures, in listening darkness,

have called life, from the small materials -

wakened the dreaming score, printed

on the creative soul of the Universe -

fulfilling itself in life; in the building

house of egg and sperm fused - foundation

power; atomic bomb found in a single cell -

choreographed explosion from first division,

multiplication; starry cluster rooting

itself in the warm red planet home -  

pool, sea, pink sky among darkness.

Pumping thumping hum eternal, thudding;

sergeant major keeping the troops in time,

root of human flower becoming conscious

of existence waiting in the water, reaching

for blood and oxygen; lassoing the mother,

conscious of identity - its star, leading role,

centre stage for now; glorious brief career

as rope of life, physical metaphor for soul,

umbilical to God by cerebral silver lines -

these words untied to lips or mouth, sailing

like dandelion parachutes - riding this line

like a stream of light - like these messages,

bearing identity. From this whole gleaming

genome, my part in the entire play - from

beginning to exit; only my lines, my share

of the script, word perfect, but knowing

the rest of the parts – is there a prompter

somewhere if I am dumb or deaf ; if I do

not listen and fail the eye I am - tooth,

the golden hair, from this unpromising

cluster of myself. It doesn’t seem even

possible - no city planned and built,

could ever be so surely executed –

beautiful; we are an orchestra, tuning

ourselves to the sound of life - echoing

through the Universe as a Word; silent,

ageless, mysterious in nature - younger

than time, older than Earth; concentrating

itself and all this glory into a single cell -

zygote, firing with creation’s spark, yet

invisible, present like pristine air-sparkle.

Splitting - now becoming more than one -

even in darkness, as any mother will know,

from love of oocyte and sperm; mysterious

cleavage answering the word in - morula –

blastocyst – blastosphere; motherless unto

blastocyst, dreaming gastrula coming to pass;

hearing the voice in darkness that charms life

out of dull chemicals - gold and seeds, buried

in winter earth, knowing flowers and jewels.

That names forgotten stars, planets, down to

the last molecule of a human cell, scale of a

butterfly wing, honey-bee’s sugar-antenna –

learning now the poem at its heart - of bowel

or gut, eye or hand; for a whole play, written

in verse, in language that has never grown old,

yet speaks the tongue of water bug and worm -

mud, swamp, sea and sand scripts. Even some

inkling of star and divine languages,

a first tongue among such darkness -

word speaking our name then, now.

DIFFERENTIATION

‘…but although the development of embryos could broadly be described by the early decades of [theTwentieth] century, it could not be explained. How do the cells move? How do they ‘know’ where they are going? When they get to their final position, how do they ‘know’ that they ought then to differentiate into lung, or liver, or bone, or whatever…Even now these questions are very far from answered. Science moves rapidly, but big questions take a long time to answer. Again, one prime reason for developing cloning technology is to address these issues. It all simply remains wonderful – and will seem even more wonderful when answers have been provided.’ Ian Wilmut, Keith Campbell, Colin Tudge, The Second Creation, Headline, 2001

In the heart of things, we have seen mysteries

In the heart of things, we have seen mysteries;

are like Druids in our white, in our veneration

of nature, now revealing herself like a spiritual

striptease – tantalizing - more desirable each layer.

And we know not what we will see, find, celebrate

among energy, force behind everything observable;

but everything prepares us to be amazed - perpetually

aghast at the knock of miracles on our shoulderblades;

where we have found the nature of wings - and angels.

‘The basics: how cells divide. The division of animal, plant, and fungal cells is of necessity intricate and in practice is a miracle of organisation, as precise as a naval regatta – and, in the behaviour of the chromosomes, ressembling one. The genetic material has to divide exactly….In practice, animals must be able to operate two forms of cell division. The standard form simply multiplies body cells…known as mitosis. But there is also a special form of cell division designed to produce gametes, which enable the diploid parent cells to generate haploid daughers. This is known as meiosis… The word ‘mitosis’ derives from the Greek ‘mitos’, meaning ‘thread’, where thread alludes to the visible chromosomes themselves; while the Greek ‘meiosis’ means ‘diminuition’, and refers to the transition from diploidly to haploidy.’ Ian Wilmut, Keith Campbell, Colin Tudge, The Second Creation, Headline, 2001

We are embroidered on the black Universe

We are embroidered on the black Universe

in silver threads – by gold sequins sparking

in whatever first light it is that fired the Sun.

Mitosis spinning chemicals - knitted scripts,

to flesh the twitching patterns; calm meiosis

producing her daughters - diploid to haploid.  

From one, many

From one, many; such an ancient tale,

this story of cells - which came first -

fertile symbol or principle of miraculous

multiplication. Dust of sun-brushed skin

lands in my palm - original star molecules;

enough information encoded in this single

shining particle - blown like a mini moving

star through the room’s lazy yellow galaxy,

to make me anew - that informed my child -

from one cell, love energy, he came to light;

making more believable the whole world -