Fluff Question: Progenoid Glands

This is something that has bothered me for quite some time actually. Does it take 1 or 2 progenoid glands to make a Space Marine? It is never really explained, just that the progenoid carries the gene seed, and that when the Marine dies, it is the duty of the Apothecary to remove it so that future Marines can be made.

We know for a fact that a Marine carries 2 glands. It is too embedded in the fluff. A bunch of BL novels describe how the Apothecary has to remove one from the neck and then punch in through the chest armour and fused ribcage to get to the second gland. But my question is as follows: were both implanted as a Neophyte?

I think that the way GW and BL writers have thought it out over time is that yes, during surgery 2 glands are put in and mature to produce future geneseed. But to me this doesn't make mathematical sense. Space Marines die at too high of a rate at their limited numbers for this to make sense. Yes an apothecary is supposed to recover it, but how many times have you read one of the following scenarios
-The Marine's Corpse is left behind
-The Marine's Corpse is ejected into space
-The Marine's Corpse is torched by a flamer
-The Marine's Corpse is reduced to slag by plasma
-The Marine's Corpse is vaporized by a melta
-The Marine's Corpse is blown up
-The Marine's Corpse is eaten by daemons/nids/orks
-The Marine's Corpse is shot up way too much
-The Marine's Corpse is hit by a Gauss weapon
-The Marine's Corpse on a ship when it goes KABOOM
Just to name a few. And really, the above are mostly the only way to kill a space marine short of removing his head.

So the issue with the above deaths? Well the apothecary can't recover the gene seed. So if two are required to make the next generation of Space Marine then that is one less Space Marine that can be made. Granted there are depositories of geneseed, but unless every chapter has like 50 of the fortresses sitting around that exist in the novel Storm of Iron, then over 10,000 years, at the rate Space Marines die in the above fashion, then each chapter would run out of gene seed.

We also know that the progenoid glands/gene seed cannot be replicated. It is well established in the fluff, and best demonstrated in the later Blood Angel novels by James Swallow, or the Horus Heresy novel Deliverance Lost. SPOILER ALERT: Okay so they did replicate it in that book, but the point of then end is that the data was destroyed and the ability to replicate and make geneseed lost to all but the Emperor.

So what are the alternatives? Well...

1- There is no alternative. Simply accept the way I first stated and assume that GW and BL employees and writers have a poor understanding of fundamental mathematics. A diminishing finite amount of geneseed will eventually see SM chapters die off.

2- One progenoid is implanted as the gene seed in a neophyte and his developing body grows a second one as a result. This would allow the numbers to grow slowly over time as it is suggested for recovering chapters, but slow enough that when a chapter falls below a critical threshold, they may die at a rate faster than they create. Examples of scenarios like this could be the Flesh Tearers and Celestial Lions.

3- A mature progenoid is removed from its host and is separated into 2 halves to make 2 new progenoids that will grow and develop in a Space Marine. This kinda combines the standard "Implant 2 remove 2 approach" while allowing room for permanent loss, since one dead Space Marine can be used to create 2 new Space Marines. I think this is really the most likely way, otherwise why would glands have to "mature". Wouldn't they always be mature, from the time they were pulled out of a cooling corpse untill the time the next host is a cool corpse himself. This suggests that each seed changes and develops in a marine, which would suggest a possibility for aberration and mutation over time, which the fluff once again suggests that apothecaries monitor for generation after generation.

4- Geneseed is removed not only at death, but from all Space Marines at some point. Basically, say once it has been in you for 50-100 years, they just take it out to implant in another. This seems the least likely really, as I have never seen it mentioned. Plus, though more delayed than option 1, it would eventually fall to the same fate. A fixed number of geneseed would ultimately see SM chapters disappear. Though it does raise the question, do apothecaries remove the progenoids before placing a brother in the sarcophagus of a dreadnought. I would hope so, otherwise it seems a waste especially since most dreadnought seem to end their life going up in a puff of smoke (and whoosh of fireball), immolating the pilot instantly.

The guy is no longer super human, why does he need them anymore? If is secretes some chemical required to sustain what is left of his advanced physiology or the demands of long term stasis, why not artificially give it to him like everything else?

5- I did however find this description online:

1. Progenoids - There are two of these glands, one situated in the neck and the other within the chest cavity. These glands are vitally important and represent the future of the Chapter, as the only way new gene-seed can be produced is by reproducing it within the bodies of the Marines themselves. This is the implants only purpose. The glands absorb genetic material from the other implanted organs. When they have matured each gland will have developed a single gene-seed corresponding to each of the zygotes which have been implanted into the Marine. These take time (5 years in the first case, 10 in the latter) to mature into gene-seed. The gene-seed can then be extracted and used to create more Space Marines.

What to make of this? Well if all that is required is 1 geneseed to make a new Space Marine, it works out. Maybe they can make a full set of implantable organs from a single geneseed, but the important part is getting that single geneseed from the host. And if one geneseed makes 1 Space Marine with 2 progenoid glands, then the numbers can work out over the finite diminishing total doom approach. This is kinda a combination of some of the earlier ideas. It would mean that 2 progenoids are implanted, and 2 geneseed removed. But then either only 1 geneseed is needed for a new space marine OR you go with option 4 above and remove geneseed before death, BUT the glands then produce another set, and another, and so on and so forth until death.

Discuss. Or I guess, Disqus.