Germ Layers: Detail

[justadream]

Some of the things that are associated with certain germ layers (e.g., brain = ectoderm) are obvious.

But is it worth memorizing the specifics?

For example, adrenal medulla = ectoderm. Adrenal cortex = mesoderm.

Thymus, thyroid, parathyroid = endoderm.

I'm finding this stuff harder to memorize than amino acids structures lol.

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[The Brown Knight]

You only need to know which ORGAN SYSTEMS are derived from which.

Ectoderm = Nervous, epidermis, senses
Endoderm = Digestive, Respiratory
Mesoderm = Musculoskeletal, dermis, all vascular systems, Urogenital

The way I remember these is through a paradox: the nervous system is the most important and delicate and yet is derived from the ectoderm as if it's not very important; the digestive/respiratory system is far more expendable and yet it's derived from the endoderm as if it's very important; almost everything else is in the mesoderm. There are more details and some organs from one system are from another germ layer, but the above is the most important. I at least wouldn't be able to recall all those specifics in test anxiety.

 

[justadream]

@The Brown Knight

Another thing I find confusing is that the Germ Cells come from the ectoderm but the rest of the reproductive system comes from the mesoderm...

 

[The Brown Knight]

@The Brown Knight

Another thing I find confusing is that the Germ Cells come from the ectoderm but the rest of the reproductive system comes from the mesoderm...

Interesting...I probably wouldn't be able to remember that on exam day though

 

[justadream]

Interesting...I probably wouldn't be able to remember that on exam day though

I can't even remember that right now lol. I opened my textbook to type that post.

 

[Czarcasm]

@The Brown Knight

Another thing I find confusing is that the Germ Cells come from the ectoderm but the rest of the reproductive system comes from the mesoderm...

Are you sure? I was told germ cells have their own delineation, separate from the 3 germ layers.

 

[Czarcasm]

From wikipedia:

Multicellular eukaryotes are made of two fundamental cell types. Germ cells produce gametes and are the only cells that can undergo meiosis as well as mitosis. These cells are sometimes said to be immortal because they are the link between generations. Somatic cellsare all the other cells that form the building blocks of the body and they only divide by mitosis. The lineage of germ cells is called germ line. Germ cell specification begins during cleavage in many animals or in the epiblast during gastrulation in birds and mammals. After transport, involving passive movements and active migration, germ cells arrive at the developing gonads. In humans, sexual differentiation starts approximately 6 weeks after conception. The end-products of the germ cell cycle are the egg or sperm.[4]

Under special conditions in vitro germ cells can acquire properties similar to those of embryonic stem cells (ES). The underlying mechanism of that change is still unknown. These changed cells are then called embryonic germ cells (EG). Both EG and ES are pluripotent in vitro, but only ES has proven pluripotency in vivo. Recent studies have demonstrated that it is possible to give rise to primordial germ cells from ES.[5]

 

[justadream]

Are you sure? I was told germ cells have their own delineation, separate from the 3 germ layers.

Interesting...

Now I'm even more unsure.

I got that info from Campbell Biology 10th ed:

 

[Oh_Gee]

i know we have to know these, but why.......... AAMC why....