Indian Journal of Veterinary Anatomy 26 (2): 113-114, December 2014 Histomorphological Study of the in Adult Marwari Goat (Capra hircus)

R. K. Barhaiya1, Malsawmkima2, Y. L. Vyas3* and D. M. Bhayani4 Department of Veterinary Anatomy and Histology, College of Veterinary Science and Animal Husbandry Anand Agricultural University, Anand-388 001 (Gujarat)

Received: 02 July 2014; Accepted: 01 August 2014

ABSTRACT

The present study was carried out on the eyelid of the adult Marwari goat (Capra hircus). The eyelid was composed of an outermost layer of typical skin, orbicularis oculi muscle, tarsal plate and the innermost layer of the palpebral . The were covered externally with typical skin containing a dense coat of fine hairs. The follicles of were located at the marginal part of skin and were devoid of arrector pili muscle. The roots of the large eyelashes were in close association with prominent sebaceous glands (glands of Zeis) and modified sweat glands (glands of Moll). Beneath the outermost layer, there was the orbicularis oculi muscles which was separated from the posterior epithelial lining of the eyelids (i.e. palpebral conjunctiva) by dens connective tissue, the tarsal plate. Within the tarsal plate, modified multilobular sebaceous glands (Meibomian or tarsal glands) were embedded. The palpebral conjunctiva was the innermost layer which consisted of the stratified cuboidal or columnar epithelium that became more squamous towards the margin of the eyelid. The tarsal gland, gland of Moll, gland of Zeis, ground substance of eye lids and the goblet cells in conjunctiva revealed a positive reaction for PAS. Key words: Eyelid, Goat, Histomorphology

The eyelids are musculofibrous dorsal and ventral plate and the innermost layer of the palpebral conjunctiva folds of thin skin continuous with the facial skin. The eyelids (Fig.1) as reported in domestic animals (Gelatt, 2007). play role to protect and exclude light from the eyes, to The eyelids were covered externally with typical skin sweep foreign bodies from the anterior surface of the eyeball containing a dense coat of fine hairs with small sebaceous and to spread liquid tears across the cornea. The eyelids and sweat glands. The thickness of epidermis varied from contain glands that lubricate the edges of the lids and help region to region and it was found to be thinnest in upper to prevent overflow of tear secretion (Gelatt, 2007). The eyelids especially in the area of tarsal glands as reported information on histomorphology of eyelids in goat is lacking. by Ahmed (2012) in cattle. The epidermis of eyelid was Hence, the present study was undertaken to provide a basis devoid of stratum lucidum (Bacha and Bacha, 2000). The to understand the pathophysiological or surgical conditions melanin granules were distributed between the cells of associated with the eyelids and for their better remedies. stratum basale and stratum spinosum. These granules were distributed between the hair follicles and dermal connective MATERIALS AND METHODS tissues (Fig. 2). The basal membrane was less wavy in the The present study was carried out on the eyelids of upper eyelids, lateral and medial of the eye, while six adult Marwari goats (Capra hircus). Samples were it was more wavy in the lower eyelids. Tactile hairs were collected from the abattoir and immediately fixed in 10% also present on and near the eyelids (Gelatt, 2007). neutral buffered formalin. The samples were processed The follicles of eye lashes were located at the by routine paraffin embedding technique (Luna, 1968) and marginal part of the skin and were numerous especially in paraffin sections of 5 to 7 µ were subjected for hematoxylin the upper eyelids. The eyelashes were varied in extension and eosin staining (Singh and Sulochana, 1996) and periodic- and diameter and were present in double or triple rows in acid Schiff (PAS) staining for demonstration of the upper and lower eyelids. The follicles of eye lashes carbohydrate (Humason, 1967). were devoid of arrector pili muscle as reported by Ahmed (2012) in cattle. The roots of the large cilia were in close RESULTS AND DISCUSSION association with prominent sebaceous glands i.e. glands of The eyelid was composed of four layers viz; outermost Zeis and modified sweat glands i.e. glands of Moll or ciliary layer of typical skin, orbicularis oculi muscle layer, tarsal glands (Fig. 3). The modified apocrine sweat gland of Moll or ciliary gland was consisted of two portions: secretory 1, 2 M.V.Sc. Scholar; 3 Prof. & Head; 4 Prof. *Corresponding author: [email protected] part and duct system. These glands were spiral, but they 113 Barhaiya et al.

Figs. 1-4 1. Photomicrograph of upper eyelid showing outermost layer covered by skin (A), having hair follicles with sebaceous glands and sweat glands, orbicularis oculi muscles layer (B), tarsal plate (C) and innermost layer of the palpebral conjunctiva (D). Masson’s trichome × 40; 2. Upper eyelid showing presence of melanin granules (green arrows) between stratum basale (SB), stratum spinosum (SP), in dermal connective tissue, stratum granulosum (SG) and stratum corneum (SC). Masson’s trichome × 100; 3. Root of the eyelashes showing prominent sebaceous glands (glands of Zeis) and modified sweat glands (glands of Moll or ciliary glands). H. & E. × 100; 4. Sweat glands (glands of Moll) lined by cuboidal cells and surrounded by myoepithelial cells (black arrow). Masson’s trichome × 400.

Figs. 5-8. 5. Photomicrograph showing orbicularis oculi muscle layer separated from the palpebral conjunctiva by dens connective tissue (tarsal plate). Masson’s trichome × 400; 6. Duct of extensively lined by keratinized epithelium. H. & E. × 100; 7. Palpebral conjunctiva lined by stratified cuboidal to columnar epithelium. Masson’s trichome × 400; 8. Upper eyelid showing PAS positive; tarsal gland, gland of Moll, gland of Zeis, ground substance of eye lids and goblet cells. PAS × 40. were not highly coiled in appearance. The epithelium of The innermost layer was lined by the mucous the gland consisted of an outer myoepithelial layer and an membrane known as the palpebral conjunctiva which inner layer of flattened cuboidal to columnar glandular cells consisted of the stratified cuboidal to columnar epithelium depending upon the activity of the cells (Fig. 4). The that became more squamous towards the eyelid margin dimensions of these glands were smaller in the lower eyelid. (Fig. 7). Goblets cells were scattered in the epithelium. The ducts of these glands emptied near the hair follicles of Many structures like tarsal gland, gland of Moll, gland of the eye lashes. Zeis, ground substance of eye lids and goblet cells in Beneath the outermost layer there was a bundle of conjunctiva revealed positive reaction for PAS (Fig. 8). orbicularis oculi muscle fibres in a row that extended nearly the full length of the eyelid. The muscles of the eyelids REFERENCES were separated from the posterior epithelial lining of the Ahmed, N.S. 2012. Histological and histochemical study of eyelid eyelids (i.e. palpebral conjunctiva) by a narrow layer of of native cattle (ox). Journal of Vetrinary Research 11: dense connective tissue i.e. tarsal plate (Fig. 5). Surrounding 120-134. the orbicularis oculi muscle, fibres of smooth muscles Bacha, W. J. and Bacha L.M. 2000. Color Atlas of Veterinary (Muller’s muscles) were scattered (Ahmed, 2012). The Histology. 2nd edn., Lippincott Williams and Wilkins, tarsal plate provided structural rigidity to the eyelids. Within Philadelphia. the tarsal plate, modified multilobular sebaceous glands Gelatt, K.N. 2007. Veterinary Ophthalmology. 4th edn., Blackwell (Meibomian or tarsal glands) were embedded (Figs. 1, 5). Publishing Asia, Victoria, Australia. They secreted lipids that stabilized the precorneal tear film. Humason, G.L. 1967. Animal Tissue Technique. 1st edn., W.H. These glands formed parallel rows of lobules, with their Freeman and Company, San Francisco and London. duct openings close to the lid margins, which were visible Luna, L.G. 1968. Manual of Histologic Staining Methods of the to the naked eye. The duct openings did not communicate Armed Forces Institute of Pathology. 3rd edn., McGraw with the hair follicle of the eyelashes. Tarsal glands were Hill Book Company, New York. better developed in the upper eyelid than in the lower eyelid. Singh, U.B. and Sulochana, S. 1996. Handbook of Histological The duct of the Meibomian gland was extensively lined by and Histochemical Techniques. 2nd edn., Premier keratinized epithelium, which was visible at the gland’s Publishing House, Hyderabad. orifice (Fig. 6). 114