Epidermal membrane (epithelion) on a llama cria
Keywords: Llama glama, llama, epidermal, camel, membrane, neonate, camelidIn both old and new world camelids, neonates are covered by a thin membrane at birth. This is most commonly referred to as the epidermal membrane (EM) but in piglets where it is also present (see Pearson, M.J. et al. 2015) it has been referred to as an epithelion. The latter term is certainly not commonly used, either with regard to pigs or when discussing camelid reproduction.
The image below shows the thin EM, partially covering the body of a cria. During late gestation the EM is relatively thick, becoming thinner towards term. At term it is thin, friable and easily brushed off by the neonate itself during vitalization. It was only because this fetus died during or shortly after birth, that the EM was partially intact.
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Below, a term male llama delivered per vagina. Death due to dystocia. A good example of the EM in a fresh state.
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The EM is perhaps 1 to 2 mm thick at most. It is comprised of keratin, resembling the epidermis when examined histologically. It contains very few nucleated cells. The EM starts to form early in gestation as an additional layer to the epidermis, being pushed away from the skin as hairs begin to form. By the end of the first trimester to mid gestation, it is obvious on gross examination of the fetus.
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The EM attaches to the mucocutaneous junctions, doing so at the mouth (as shown above), nostrils, eyes, prepuce, vulva and anus. (below). Therefore the functions of these orifices are not impeded by its presence. There is for example, no chance that the EM will cause peripartum asphyxia.
As is shown below, the EM does not cover the claws either. It is attached only as far distal as the coronary bands.
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In all camelids, amniontic fluid is thought to be less viscous and lubricating than it is in most other animals. This leads to the logical assumption that the EM (which is extremely slippery when wet) assists in lubricating the fetus during its passage through the birth canal.
Selected references
Fowler, M.E. and Olander, H.J. 1990 Fetal membranes and ancillary structures in llamas (Lama glama). Am J Vet Res 51: 1495-1500
Holubar, K. and Schmidt, C. 1994. Dermato-pathologia 1792 and Henry Seguin Jackson (1750?-1816): a bicentennial. J. Royal Society of Medicine. 87:464 (The epithelion is mentioned in this paper)
Merkt. H. et al. 1988. The presence of an additional partial membrane and its function in the newborn guanaco (Lama guanacoe). Theriogenology. 30:437-439
Pearson, M.J. et al. 2015. Gross and histological description of the epidermal membrane found on normal neonatal piglets. Lab animal 44: 445-447
