MORPHOLOGICAL STUDY OF FISSURE AND LOBES IN FETAL LUNGS

Address for Correspondence: Dr.V.Vimala, M.D, Assistant Professor, Department of Anatomy, Coimbatore Medical College, Coimbatore, Tamilnadu, India, Email id: dr.vimal.v@gmail.com Background: The lungs are the essential organs of respiration which are divided into lobes and fissures. Fissures help in a more uniform expansion of lungs. Knowledge about the fissures is helpful in appreciation of lobar anatomy and for locating bronchopulmonary segments and it is important for anatomists, pediatrician, radiologists, cardiothoracic surgeons and also for clinicians. Materials and methods: 50 spontaneously aborted fetuses were collected from labour room of Obstretrics and Gynaecology Department of PSG Institute of Medical Science and Research Centre, Coimbatore and the study was conducted in the Department of Anatomy. The morphological details of fissures and lobes of the lungs and presence of any variation in the fissures and accessory fissure were studied. Results: Out of 50 specimens in the age group of 10 weeks to 39 weeks of gestation, the horizontal fissure was incomplete in 35 fetuses (68%), complete in 14 fetuses (28%), absent in 1 fetus (2%) and accessory fissure was found in 1 fetus (2%). Conclusion: Awareness of the variations in the lobes and fissures of the lungs is important for radiologists for proper diagnosis and to surgeons for performing segmental lung resections.


INTRODUCTION
lung. On the posterior border it is either level with the spine of T4 or slightly lower. It runs along the costal surface and cuts the inferior border of the lung at sixth costochondral junction 7.5cm from the midline and reappears on the mediastinal surface and finally it ends at the lower end of the hilum. The short horizontal fissure separates the superior and middle lobes. It passes from the oblique fissure near the midaxillary line horizontally forwards to the The lungs are the essential organs of respiration. They are situated on each side of the heart and other mediastinal contents. The right lung is divided into upper, middle and lower lobes by an oblique and a horizontal fissure. The left lung is divided into upper and lower lobes by oblique fissure. In each lung the oblique fissure begins from the mediastinal surface above and behind the hilum and cuts the posterior border of the anterior border of the lung, level with the sternal end of fourth costal cartilage and then passes backwards to the hilum on the mediastinal surface [1]. The fissures facilitate the movement of the lobes in relation to one another, which will accommodate the greater distension and movement of lower lobes during respiration and thereby it helps in uniform expansion of whole lung. These fissures may complete, incomplete or absent. The lung can also have accessory fissures which may be single or multiple dividing the lungs into many lobes. This is significant anatomically, radiologically and clinically. So awareness of their variations is essential in performing lobectomies and in surgical resection [2]. Considering its clinical significance and also studies on fetal lung is less, we have conducted study in fetal lungs. Embryology: Defective pulmonary development gives rise to variation in fissures and lobes. Fissures are spaces present between bronchopulmonary segments or buds in fetal life. Later on they get obliterated except along two planes which persist after birth as oblique and horizontal fissures. Non-obliteration of some of these spaces is responsible for the presence of accessory fissures [2].
The present study was conducted in the Department of Anatomy, PSG (IMS &R), Coimbatore, India. Ethical clearance was obtained from institutional ethical committee. After getting informed consent from the parents 50 spontaneously aborted fetuses ranging from 10 weeks to 39 weeks of gestation were collected from the Obstretrics and Gynaecology Department of PSG (IMS&R). After collection the fetuses were immersed in 500-1000ml of 10% formalin for fixation. The morphological details of fissures and lobes of the lungs and presence of any variation in the fissures and accessory fissure were studied.

MATERIALS AND METHODS
fetuses (Fig-2), absent in 1 fetus (Fig-3) and accessory horizontal fissure was found in 1 fetus (Fig-4) [ Table -1]. Oblique fissure: The fetal lungs were examined for any variations in the oblique fissure. The oblique fissure was found to be normal without any variations in both lungs [ Table -3].

RESULTS
Horizontal fissure in the right lung: Out of 50 specimens in the age group of 10 weeks to 39 weeks of gestation, the horizontal fissure was incomplete in 35 fetuses (Fig-1), complete in 14 Table1: Horizontal fissure in the right lung.

S.No
Horizontal        [4]. Eroje et al reported two anomalous right lungs of adult specimens which displayed variation in the pattern of fissures and lobes. One lung showed a complete horizontal fissure and an incomplete oblique fissure. In other lung the horizontal fissure was absent [5]. Enakshi  showed accessory fissure [7]. Sarita et al reported presence of accessory fissure in right lung in two specimens. In one lung the accessory fissure was extending horizontally backwards from the oblique fissure at midaxillary line towards the vertebral part of the medial surface and it was meeting the normal horizontal fissure. In another specimen it was not meeting the horizontal fissure [8]. In our study, Out of 50 specimens in the age group of 10 weeks to 39 weeks of gestation, the horizontal fissure was incomplete in 35 fetuses (68%), complete in 14 fetuses (28%), absent in 1 fetus (2%) and accessory fissure was found in 1 fetus (2%).
Meenakshi et al stated that out of 44 adult lungs in the right side the horizontal fissure was absent in 5 and middle lobe was not appreciated. The horizontal fissure was incomplete in 19 lungs and oblique fissure was incomplete in 11 lungs and lobulation was imperfect. In two of the specimens the horizontal fissure was absent and oblique fissure was incomplete. In left lungs the oblique fissure was incomplete in 14 and accessory fissure were found in 3 specimens [2]. Zareena (2014) observed that out of 10 fetal lung specimens, in 4 fetuses the right side lungs showed the normal pattern of oblique fissure, in 2 fetuses they showed incomplete oblique fissure in the right lung and in 4 fetuses the right side lungs showed incomplete horizontal fissure. In 6 fetuses the left side lung showed the normal pattern of complete oblique fissure [3]. Varalakshmi  Knowledge about the variation in the fissures and lobes is important for anatomists during routine dissection of cadaver by undergraduates and postgraduates students and for paediatrician in treating premature infants. It is also