Morphology of deep gland of the third eyelid in pig foetuses

The morphological and histological examinations of the deep gland of the third eyelid were carried out on pig foetuses coming from the 35th, 50th, 63rd, 94th and 112th day of gestation. The morphological examinations were conducted using 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. For the histological examinations, the whole eyeball with developing accessory organs was collected from the pig foetuses on the 35th day of gestation. On the 50th, 63rd, 94th and 112th day of gestation only the deep gland of the third eyelid was collected. Staining with haematoxylin-eosin and Azan method was performed. It was found during the examinations that the process of the formation of the deep gland of the third eyelid starts on the 35th day of gestation. On the 50th day of gestation, the gland cells are evenly distributed in the connective tissue stroma. On the 63rd day of gestation, the connective tissue divides the gland parenchyma into indistinct lobes composed of 6-15 lobules. On the 94th day of gestation, the gland lobes become visible; the efferent ducts are situated in the central part of the lobe. On the 112th day of gestation, the lobes are composed of a high number of lobules composed of two kinds of excretory ducts. The first type of the excretory ducts is lined with the simple cuboid epithelium whose nuclei are situated at the base of the cell. The other type of the excretory ducts is lined with the simple cuboid epithelium whose nuclei are round and arranged less or more peripherally.