THE PRENATAL DEVELOPMENT OF THE EYELIDS OF THE ONE-HUMPED CAMEL (CAMELUS DROMEDARIUS)

摘要

Fifty-five camel fetuses ranging from 2.8 to 110cm crown vertebral rump length (CVRL) were used in this study. Thirty-five fetuses were used for gross morphology and the other twenty for paraffin sectioning and light microscopy. The upper and lower eyelids appear as two ectodermal folds at 2.8cm CVRL, then grow until they meet and fuse at 8.4cm CVRL. Fusion lasts until 58cm CVRL, the lids then start to reopen at 66cm CVRL. The palpebral skin and conjunctiva display striking changes throughout the prenatal life. The first indication of hair follicles is seen at 8.4cm CVRL, while sweat and sebaceous glands are first demonstrated in fetuses of 36.5cm CVRL. A cornified palpebral skin with complete cutaneous structures including eyelashes and tactile hairs is demonstrated in fetuses of 66cm CVRL. The one-humped camel lacks tarsal glands. However, hair follicles are demonstrated on the conjunctival side of the eyelids, only near the medial canthus, in fetuses of 36.5cm CVRL. At 110cm CVRL (full-term fetuses), this part of the palpebral conjunctiva appears hairy and associated with well-developed sebaceous glands.