The Hormonal prenate

De omstandigheden zijn de architect.
Het DNA vertegenwoordigt het genotype maar ook het fenotype zoals kleur etc.... Het staat voor de kwaliteit van de eiwitten waarvoor het codeert. (leverancier)
Het metabolisme is de drijvende kracht.  

Gezamelijk zijn ze verantwoordelijk voor de "morpho"genesis. 

 

Het kind.
Placenta en corpus.
Groei en dus ontwikkeling heeft tot gevolg dat functies van de placenta verhuizen naar de corpus = incarnatie.

Na volledige overdracht is de placenta klaar en heeft het kind alle functies geoefend en is klaar voor verdere groei op zichzelf.
 

Placenta verzorgt dus in eerste instantie uitwisseling van hormonen en imuunfactoren.
Er is nog geen uitwisseling van O2 tot na de 8ste week alle aanleg in basis ligt en dat weefsels sterk genoeg zijn om een grotere [O2] aan te kunnen. Er zou anders te veel oxidatie plaats hebben. 

"Daar krijg je een aangebrand embryo van."

Verder in volgelvlucht langs de basis ontwikkeling van het embryo en de intiële hormoonhuishouding.

Zodra het eitje bevrucht is gaat het corpus luteum  HCG uitscheiden {} verdubbeld dagelijks in maternaal circulatie tot plm 7de week., daarna wordt productie overgenomen door de placenta.

 

Hormone Types

 

Steroid biosynthesis pathway

Hormone Actions

 

Ontwikkeling van de neurocranium en (voor)darm en de invloed van de eerste hormonen

Pinealis

  • Pineal -week 5 (CS 14): a slight irregularity in the surface outline of the intact head corresponds to the future pineal body (O'Rahilly et al. 1982).
  • week 5 (CS15) pineal body is detectable in the roof of the diencephalon (Stadium I of Turkewitsch)

The fetal circadian rhythm is not just present simply as the initialimmature expression of a mechanism that has function in the postnatal animal only.

It is proposed that the fetal suprachiasmatic nucleus (SCN) of the hypothalamus and fetal organs are peripheral maternal circadianoscillators, entrained by different maternal signals.

Conceptually, the arrangement produces internal temporal order during fetal life, inside the maternal compartment.

Following birth, it will allow for postnatal integration of the scattered fetal circadian clocks into an adult-like circadian system commanded bythe SCN.

 

Pinealis and supra chiasmatic nucleus

  • Melatonin and stable circadian rhythms optimize maternal, placental and fetal physiology
  • Melatonin, of both pineal and placental origin, has essential functions in fetal maturation and placenta/uterine homeostasis.
  • Circadian clock genes, which are components of all cells including those in the peripheral reproductive organs, have important roles in reproductive and organismal (fetal and maternal) physiology; 
  • The propensity for parturition to occur at night may relate to the synergism between the nocturnal increase in melatonin and oxytocin."
  • Melatonin as a central molecule connecting neural development and calcium signaling[4] "Melatonin (MEL) is a neuroendocrine hormone secreted by the pineal gland in association with the suprachiasmatic nucleus and peripheral tissues. MEL has been observed to play a critical role in the reproductive process and in the fetomaternal interface. Extrapineal synthesis has been reported in mammalian (also human) models during pregnancy, especially by the placenta tissue.
  •  

refferences:

Review:Circadian rhythms in the fetus

The Development of Circadian Rhythms inthe Fetus and Neonate


entrainment

 

 

Hypofysial hormones and activation of stemcells for the next generation.

At week 

(4) Pituitary - basement membranes of the craniopharyngeal pouch and the brain are clearly in contact

(5) craniopharyngeal pouch is prominent and the notochord appears to be inserted into its dorsal wall. The craniopharyngeal pouch has become elongated and blood vessels are beginning to grow in between the basement membranes of the pouch and brain.

Oxytocin is a small neuropeptide consisting of  9 amino acids.

Throughout the human life span, specific neurons manufacture oxytocin; these cells are abundant in distinct areas of the mammalian hypothalamus: the paraventricular and supraopticnuclei. SCN

Oxytocin from these cells is carried to and released from the posterior pituitary gland into circulation and fromthere is distributed throughout the body. 

Within the centralnervous system, oxytocin reaches nearly all parts of the brainstem, midbrain, cortex, and spinal column. In addition to the hypothalamus producing it, peripheral organs and tissues also may secrete oxytocin, but the pituitary is believed to be the predominant source of oxytocin in circulation.

Thyroid en thymus

T3 enT4  have a prominent place in brain development and myelinisation

Especially T4 levels are measured high, pressence has influence on cortex expansion. Source T4 and T3 are maternal and prenate.

 

Thyroid hormone deficiency to the brain during development is caused by iodine deficiency, congenital hypothyroidism,and maternal hypothyroidism and hypothyroxinemia

ref: THYROID HORMONES IN BRAIN DEVELOPMENT AND FUNCTION September 3, 2015 Juan Bernal, MD

www.endotext.org.

references;

The Current Embryology of the foregut and its deratives 

 

Hersen-darm as: het fenomeen serotonine

Een van de eerste hormonen die het embryo zelf gaat produceren is het serotonine hormoon.

  • Serotonine is een hormoon en neurotransmitter stof die van invloed is op veel lichamelijke processen.
  • Het is een stof die vooral actief is in de zogenaamde hersen_darm as. Deze as wordt vertegenwoordigd door voornamelijk het autonome zenuwstelsel met ‘serotoninerge’ vezels. Aan beide zijden van deze vezels wordt serotonine geproduceerd.
  •  Dat wil zeggen een deel wordt in de hersenstam geproduceerd, maar sinds een aantal jaren weten we dat het overgrote deel van de serotonine in het enterisch zenuwstelsel, in de darmen geproduceerd wordt.
  •  De serotonine in het enterische deel draagt voornamelijk zorg voor de gastro/intestinale functies (darm functies). Uitscheiding, peristaltiek, vasolidatie (versterkte doorbloeding), pijnperceptie en misselijkheid. Het enterisch zenuwstelsel is hoofdzakelijk afferent.(informatie richting hersenen) 
  • De serotonine productie in de raphe nuclei in de hersenstam, heeft invloed op slaap, gemoed, agressie en seksueel gedrag. 
  • De serotonine regulatie vertoont kenbaar leeftijdgebonden aanpassingen, begint prenataal en gaat het gehele leven door. De sertoninerge zenuwvezels behoren tot de vroegst aangelegde paden. De piek in netwerk uitbreiding vindt plaats tussen het 3de en 18de levensjaar. Waarna de groei weer langzaam afneemt

Het enterisch zenuwstelsel (enterisch staat voor het intestinale of wel darm stelsel) is geheel autonoom en vertegenwoordigt de meest diverse neurochemische component in de periferie van het zenuwstelsel.

Het enterisch systeem is embryonaal aangelegd vanuit vagale innervatie (embryonaal voor en midden darm) en voor een deel als derivaat (afstammend van) van de sacrale neurale lijst ( embryonale eind darm).

Rond de zevende week is het enterisch zenuwstelsel evenals de hele darmtractus aangelegd.

Logisch want de aanleg van de functies gaat nagenoeg gelijk op, het enterisch systeem wordt in 2  lagen in de darmtractus aangelegd. (Dit zijn de plexi van meissner en auerbach).

Nieren ACE

Origin of the hematopoietic system in the human embryo Julien_et_al-2016-FEBS_Letters

ACE (CD143) plays a major role in the haemangiogenesis.Adult-type lympho-myeloid hematopoieticprogenitors are first generated in the aorta-gonad-mesonephros region betweendays 27 and 40 of human embryonic development, but an elusive bloodf orming potential is present earlier in the underlying splanchnopleura

Angiotensinconvertingenzyme (ACE, also known asCD143), a recently identified cell-surfacemarker of adult human hematopoieticstem cells, is already expressed in all presumptive and developing bloodformingtissues of the human embryo and fetus: para-aortic splanchnopleura, yolksac, aorta-gonad-mesonephros, liver, andbone marrow (BM).

Bone marrow is the last resource that will poduce hemapoetic cells.

The Fetal liver will perform the main blood genesis during deveopment until birth slowly reducing and handing over to the Bone Marrow.




Lever/duodenum/Pancreas

Liver (CS 12 onward): partly forgut/partly septum mesenchym.

  • Main function is taking over bloodcel production from yolk /aorta/reproduction organs andmesonephros. In second trimester fully responible for all HB production.
  • As from 3rd trimester slowly shifting to BM which completely take over after 6 weeks PP.
  • Liver already active in fat and glyc. production, in sync wit Pancreas development.

Pancreas

At the foregut/midgut junction the septum transversum generates 2 pancreatic buds (dorsal and ventral endoderm) which will fuse to form the pancreas. The dorsal bud arises first and generates most of the pancreas. The ventral bud arises beside the bile duct and forms only part of the head and uncinate process of the pancreas.

In the fetal period islet cell clusters (icc) differentiate from pancratic bud endoderm. These cell clusters form acini and ducts (exocrine). On the edge of these cell clusters pancreatic islets (endocrine) also form.Pancreatic hormonal function is to secrete insulin and glucagon which together regulate blood glucose levels and also somaostatin.

The pancreas 'exocrine function begins after birth', while the endocrine function (hormone release) can be measured from 10 to 15 weeks onward. 

Pancreas adult

  • Functions - exocrine , 99% by volume; endocrine (pancreatic islets) 1% by volume
  • Exocrine function - "begins after birth"
  • Endocrine function - from 10 to 15 weeks onward hormone release, insuline and glucagon and somatostatine.


Total endocrine overview

https://embryology.med.unsw.edu.au/embryology/index.php/Template_talk:Endocrine_embryo_table

 

Calcium huishouding

Calcium maintenance in Mother and child

About 80% of the calcium present in the fetal skeleton at the end of gestation crossed the placenta during the third trimester and is mostly derived from dietary absorption of calcium during pregnancy. Intestinal calcium absorption doubles during pregnancy, driven by 1,25-dihydroxyvitamin D (calcitriol) and other factors, and this appears to be the main adaptation through which women meet the calcium demands of pregnancy.


25-hydroxyvitamin D or calcifediol (25OHD) readily crossesplacenta
 ( cord blood 25OHD levels generally range from 75% to near 100% of the maternal value (6 , 7 ). A common concern is that the placenta and fetus will deplete maternal 25OHD stores, but this does not appear to be the case. Even in severely vitamin D deficient women there was either no change or at most a nonsignificant decline in maternal 25OHD levels during pregnancy .

 Total calcitriol levels double or triple early in pregnancy and stay elevated until parturition whereas free calcitriol levels have been found to be increased only in the third trimester. There are several unusual aspects about this situation. PTH is normally the main stimulator of the renal 1 -hydroxylase; consequently elevated calcitriol values normally mandate high PTH levels


Calcitonin

Serum calcitonin levels are increased during pregnancy and may derive from maternal thyroid, breast, decidua, and placenta. Whether calcitonin plays an important role in the physiological responses to the calcium demands of pregnancy is unknown. Calcitonin has been proposed to protect the maternal skeleton against excessive resorption during times of increased calcium demand. There are no clinical studies which have addressed this question; since multiple tissues express calcitonin during pregnancy, it would require study of women who lack the gene for calcitonin or the calcitonin receptor. 


Prolactin and placental lactogen both increase during pregnancy and activate prolactin receptors. Osteoblasts express prolactin receptors, and prolactin receptor
Prolactin or placental lactogen regulate skeletal metabolism during pregnancy.

Circulating oxytocin levels also rise during pregnancy (20 ), and the oxytocin receptor is expressed by osteoclasts and osteoblasts (21 ).
 Oxytocin has been shown to stimulate osteoblast differentiation and function, stimulate osteoclast formation, but inhibits osteoclast function and skeletal resorption.
Taken together these data predict that oxytocin regulates bone metabolism during pregnancy but this has not yet been directly studied in vivo .

G. Intestinal Calcium Absorption

Intestinal absorption of calcium doubles as early as 12 weeks of pregnancy and appears to be the major maternal adaptation to meet the fetal need for calcium.
however, intestinal calcium absorption doubles in the first trimester, well before the rise in free calcitriol levels during the third trimester.

H. Renal Handling of Calcium

The doubling of intestinal calcium absorption in the first trimester means that the extra calcium must be passed to the fetus, deposited in the maternal skeleton, or excreted in the urine. 

Renal calcium excretion is increased as early as the 12th week of gestation and 24 hour urine values (corrected for creatinine excretion) can exceed the normal range. Conversely, fasting urine calcium values are normal or low, confirming that the hypercalciuria is a consequence of the enhanced intestinal calcium absorption. 

Pregnancy is recognized as a risk factor for kidney stones and the absorptive hypercalciuria of pregnancy is one reason for this. 

I. Skeletal Calcium Metabolism and Bone Density/Bone Marker Changes