Morphology of the third eyelid and superficial gland of the third eyelid on pig fetuses.
The morphological and histological examinations of the third eyelid and superficial gland of the third eyelid were conducted in pig fetuses coming from the 20th, 24th, 27th, 30th, 35th, 50th, 63rd, 94th and 112th day of gestation. The morphological examinations were carried out by applying the method of macroscopic preparation with a forehead magnifying glass and binocular (magnification 1.5-5.0x). In order to make anatomical elements more visible, 60-80% absolute alcohol and 0.5-4% acetic acid solution were used for the examinations. On the 20th, 24th, 27th and 30th day of gestation, the whole fetuses were collected for the histological examinations. The whole eyeball with developing accessory organs was collected from the pig fetuses on the 35th day of gestation. On the 50th, 63rd, 94th and 112th day of gestation, only the superficial gland with the third eyelid was collected. Staining with haematoxylin-eosin (H-E) and Azan method was performed. On the 20th, 24th, 27th and 30th day of gestation, the primordia of the glandular epithelium were not found in the examined material. The process of the third eyelid and superficial gland formation starts on the 35th day of gestation. On the 50th and 63rd day of gestation, the gland surrounding the cartilage of the third eyelid is composed of the high amount of loose connective tissue and gland cells which give rise to excretory segments. On the 94th day of gestation, the gland lobes become visible, the efferent ducts form. On the 112th day, the cartilage of the third eyelid assumes the appearance of the mature hyaline cartilage. The excretory segments are composed of simple cuboid epithelium with a large, round nucleus arranged less or more peripherally. Their number increases 2- or even 3-fold at the end of gestation.
Klećkowska-Nawrot
J
J
Department of Anatomy and Histology, Faculty of Veterinary Medicine, University of Environmental and Life Sciences in Wrocław, ul. Kozuchowska 1/3, 51-631 Wrocław, Poland. lestat_v@poczta.onet.pl
Dziegiel
P
P
D000818:Animals; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D007150:Immunohistochemistry / Q000662:veterinary; D009541:Nictitating Membrane / Q000033:anatomy & histology / Q000196:embryology / Q000473:pathology; D013552:Swine / Q000196:embryology*