Anatomy, histology and variations of carotid body and carotid sinus in autopsy cases

Carotid Body (GC) is one of the most important paraganglia which functions as a chemoreceptor organ modulating blood CO2 and O2 pressure and blood pH levels. Carotid sinus (CS) contains baroreceptors which detect the changes in blood pressure and then relay the information to central nervous system. These two small but highly specialized structures, which lie at the carotid bifurcation (CB), are of vital importance to body homeostasis. We performed anatomic and histologic studies (total cell number and volume), investigated demographics, correlations to the other structures (heart, lung, CCA, ECA) and we aimed to establish possible correlations We aimed to examine morphology and morphometry of GC and CS, and investigate correlations with other structures such as lung and hearth.Our study was conducted on 25 forensic autopsy cadavers who were between 3rd and 5th decades and male. Demographic information and weights of heart, left and right lungs were noted. CB area was dissected, GC and CS were observed. Three kinds of staining methods were used for histological study, namely Hemotoxilen-eozin, triple stain, Cresyl fast violet. Stereologic study consisted of GC volume estimation and T1, T2 and total cell counting. Cavalieri method was used for volume estimation and optic fractionator, which is one of the particle counting methods, was used for cell counting. Thickness and lumen area of CS, CCA and ECA were measured.In the anatomic study, 25 GCs were examined. 80% of them were ovoid, 8% of them had two lobes connected at one end forming a ?V? shape, 8% of them had two lobes with separate stalks and 4% of them was leaf-shaped. Body and stalk length of GC was found to be 3,376±0,644 mm and 2,216±1,340 mm, respectively. 21 GCs started superior to the CB level, two GCs started immediately below the superior end of CB. Two GCs started at the level of CB and had no stalk.GC volume was found to be 4,677±2,236 mm3. T1, T2 and total cell number was calculated as 2 326 328 ±1 215 328, 1 413 927 ±768 210 and 3 740 256 ±1 982 678, respectively. Cell density, which means cell number per volume unit, was 509 685±157 835 cell/mm3 for T1, 308 437±97 483 sayı/mm3 for T2. T1/T2 ratio was 1,657±0,069.There was a positive correlation between GC volume and BMI (r=0,472; p=0,017). There was a positive correlation between GC volume and CCA thickness (r=0,415; p=0,039), and between GC volume and CS thickness (r=0,539; p=0,005). GC volume had positive correlations with T1 (r=0,783; p=0,000), T2 (r=0,790; p=0,000) and total cell number (r=0,786; p=0,000). There was a positive correlation between GC volume and right lung weight (r=0,491; p=0,013) and total lung weight (r=0,444; p=0,026). But no significant correlation between GC volume and left lung weight was found. We also observed that there was a significant correlation between GC volume and heart weight (r=0,445; p=0,026).CS wall thickness was 598 ±113,1 µm. CS lumen area was 12,03±2,703 mm2. We found that CCA thickness was 789±169,9 µm and CCA lumen area was 15,98±3,405 mm2. ECA thickness was 488±107,8 µm and ECA lumen area was 7,256±1,942 mm2.We found that CS thickness changed with age. There was a positive correlation between CS thickness and age (r=0,508; p=0,01). There was a strong positive correlation between CS thickness and weight of the right lung (r=0,543; p=0,005), between CS thickness and heart weight (r=0,628; p=0,001). There was a positive correlation between CS thickness and CCA (r=0,742; p=0,000) and between CS thickness and ECA (r=0,688; p=0,000). We found a positive correlation between CS thickness and T1 (r=0,411; p=0,041), T2 (r=0,432; p=0,031) and total cell number (r=0,419; p=0,037) of GC.We consider that the importance of GC and CS will increase as novel techniques and tools are employed in studies on these structures which stil have many unexplored aspects. In conclusion, we think that our study will contribute to the basic and clinical science, may provide a frame of reference for future studies as this is the first study to estimate T1, T2 and total cell numbers, may provide clarification on various disorders and surgical issues.