The study is devoted to the morphological characteristics of the maturation of lung tissue structures in the fetal period. Fetal histology of the lungs presents the intrauterine development of lung tissue in four successive stages: pseudoglandular, canalicular, saccular and alveolar, each has specific morphological criteria. The following morphological features are predetermined: the development of alveolar epithelium, the ratio of mesenchyme towards the area in alveolar spaces, the degree of proliferation and location of vessels of the microcirculatory bed towards prealveolar partitions. During the fetal period the alveolar columnar epithelium is flattened and differentiates into alveolocytes type I lung histology with the demonstration of histological preparations of the lungs at different stages of intrauterine development. Keywords: fetal lungs, prealveolar structures, pseudoglandular stage, canalicular stage, alveolar stage, alveolar capillary membrane, immunohistochemical study. 16 and II, the area of the mesenchyme gradually decreases and by the birth of a full-term newborn kid it is present mainly in the thickness between the alveolar septa, microcirculation vessels, initially laying deep in the thickness of the mesenchymal tissue, gradually proliferate, approach the pre-alveolar epithelium, channeling it with the formation of alveolar capillary membranes. Air exchange in the lung tissue is mainly provided with two factors: the presence of second-order alveolocytes capable of producing surfactant, and a sufficient formation of alveolias well. This work summarizes the basics of fetal lung histology with the demonstration of histological preparations of the lungs at different stages of intrauterine development.

Background: The incidence of acute SAH has been estimated at 2–22 cases per 100 000 persons per year. The most common cause of basal acute SAH is a ruptured cerebral aneurysm. Cerebral vasospasm in the first 2 weeks after aneurysmal subarachnoid hemorrhage is recognized as a major predictor of delayed cerebral ischemia. From 2014 through 2018, 5272 patients with a stroke (amongst them 20.4% were patients with aSAH) were hospitalized in the 3rd State Central Hospital of Mongolia. Objective: To study the clinical features of the cerebral vasospasm and dopplerosonography parameters in the aSAH patients. Materials and Methods: The methods, methodology and ethics of the research work were discussed at a Research meeting of Ethics Control Committee of the Mongolian National University of Medical Sciences held on December 22, 2017 (No2017 / 3-05), and the study was performed in accord with approval.
60 patients with aSAH (hospitalized from 2017 to 2018 year) were enrolled in the case-control study. Informed consent were obtained from each participants. Clinical condition of participants was classified by Hunt-Hess scale (HHS). Cerebral vasospasm degree was graded by Lindegaard index. Results: 52.5% of the participants were men and 47.5% were women. Average age was 49.9±12. When clinical condition degree was compared to vasospasm grade it was revealed that amongst 1st degree of Hunt-Hess scale (HHS) group 11.1% of enrolled patients’ spasm was normal or had no spasm, while it was observed either 44.4% mild and moderate spasm. In the 2nd degree of HHS group: normal in 6.9%, mild in 3.4%, moderate in 86.2%, and severe spasm was in 3.4%. In the 3rd degree of HHS group, 11.1% had no spasm, moderate spasm was in 77.8%, and severe spasm was in 11.1%. In 4th degree of HHS group, 71.4% were with moderate spasm, 28.6% were with severe spasm (p = 0.001).
When the Hunt-Hess Scale was compared to the Sinus Rectus 1st degree of Hunt-Hess scale (HHS) group Sinus Rectus was normal for 22.2% patients, mild for 66.7% and severe for 11.1%. Though 4th and 5th degree of Hunt-Hess scale (HHS) groups’ Sinus Rectus mild for 7.1% normal, 50.0% mild and 42.9% severe (p=0.007). Thus whenever the clinical condition worsened the cerebral intracranial pressure was increasing. Conclusion aSAH patients clinical complication degree were directly associated with the cerebral vasospasm revealed by the transcranial dopplerosonography. Therefore, the evaluation of Hunt-Hess scale has an important significance in the prevention from clinical complications and in the selection of the appropriate treatment approaches for aSAH patients.