T.S. of medulla oblongata

   The medulla oblongata is the part of the brain that mainly deals with involuntary functions that are essential for life. It is the lowest part of the brain. It shows inner grey matter and outer white matter.
   The medulla contains many centres that control the viscera. These include the Respiratory Centre, Cardiac inhibitory Centre, Vasomotor Centre, etc.
   These centres are actually a collection of nuclei. For instance, the Respiratory Centre includes the NTS (Nucleus Tractus Solitarius), Nucleus Ambiguous, etc. The Cardiac Inhibitory Centre (CIC) includes the dorsal nucleus of vagus.
   Although we can point out the nuclei that belong to a particular centre, the functions of the centre per se is not the only work of each nucleus. The nuclei work together in a Co ordinated manner to maintain homeostasis.
   For example, the NTS is said to belong to the Respiratory Centre to cause inspiration on simulation. However, that is not it's only function. When the blood pressure falls down, the nucleus tractus solitarius is involved in the baroreceptor reflex. The taste inputs are also sent to the NTS via the 3 nerves of taste - facial(VII), glossopharangeal(IX) and vagus(X) nerves.
   Another example is that the CIC also functions to supply nerves to other viscera of the body. 3 sections of the medulla oblongata have been taken - 1 at sensory decussation level, 2nd at the motor(pyramidal) decussation level and 3rd at the level of the olives(Floor of 4th  ventricle).
   The labelling includes many short forms to fit in everything. I am really sorry for the short forms. But here are the full forms -
ST=SpinoTectal
DSC=Dorsal Spino Cerebellar
VSC=Ventral Spino Cerebellar
LST=Lateral Spino Thalamic
AST=Anterior Spino Thalamic
S-Olivary=Spino Olivary
RS=Rubro Spinal
VS=Vestibulo Spinal
TS=Tecto Spinal
OS=Olivio Spinal
G=nucleus gracilis
C=nucleus cuneatus
Crosshatched lines= Reticular Formation
ICP=Inferior Cerebellar Peduncle
P=pyramid
V. Coch. N.= VestibuloCochlear(VIII) Nerve
A=nucleus ambiguous
Roman numerals=number of the cranial nerve
MLB=Medial Longitudinal Bundle
TS=TectoSpinal
IVN=Inferior Vestibular Nucleus
MO=Medial Olivary
DO=Dorsal Olivary
D. Coch. N=Dorsal Cochlear Nucleus

Urogenital system development

The urogenital system includes the kidney, cloaca, uterus, rectum, anal canal, derivatives of the  mesonephric and paramesonephric ducts, etc. The  ureteric bud penetrates the metanephric mesoderm to connect the kidney with the ureter. There are also many anomalies that can happen due to faulty development of the urogenital system. This is my last post on embryology models because I don't have pictures of any more embryology models. Hope you had fun reading through. :)

Anomalies of uterus

The uterus is formed by fusion of the paramesonephric ducts. Any anomaly in such fusion or of paramesonephric duct formation leads to uterine anomalies.

Development of pancreas

The pancreas (pan=all ; creas=flesh) develops from the ventral and dorsal pancreatic buds. The ventral pancreatic bud appears on the 30th day. It shifts from the right to the left side towards the dorsal pancreatic bud in the sixth week. The buds then fuse as shown in the model.

Development of stomach

The rotation of gut is involved in stomach development. Due to this rotation many important relations are formed between organs. It also helps fit all the abdominal contents well into it. The stomach is the part of the gastrointestinal tract between the esophagus and the small intestine.

Aortic arch anomalies

The aortic arches are formed in such a manner that each arch connects the aortic sac to the dorsal aorta. The first arch artery forms the maxillary artery. The second arch artery forms the stapedial artery for some part of fetal life after which it contributes to a part of external carotid artery. The arteries that remain are shown in red while the ones that disappear are shown in white.

Fetal circulation

The fetus doesn't breathe or eat anything in utero. It, however, can drink the amniotic fluid around it. It receives it's nutrition, oxygen requirement and waste  excretion via maternal blood. Things enter the fetus via the umbilical veins and exit via the umbilical arteries. Thus, unlike other arteries and veins, the umbilical veins carry oxygenated blood while the umbilical arteries carry  deoxygenated blood. Such contrast is also seen in the pulmonary artery and vein. Another interesting thing that caught my mind was that how does a fetus use the bladder or is it unused...on searching online, I found out that it is used to release water (not urine) into the surroundings and lack of such function can lead to hydramnios.