The structural characterization of the lacrimal gland in the adult dog (Canis familiaris)

Abstract

To elucidate the macroscopical and microscopical structure of dog's lacrimal gland, 15 adult dogs (Canis familiaris) were utilized in this study. Macroscopically, the lacrimal gland was located on the dorsolateral aspect of the eyeball and bounded dorsolaterally by the orbital ligament, zygomatic process of the frontal bone and frontal process of malar bone. Its shape was nearly rectangular with the average width (1.38 ± 0.13 cm) and length (1.52 ±0.12 cm). In between the dorsal and lateral rectus muscles, the lacrimal artery, vein and nerve were observed. Microscopically, the lacrimal gland was enveloped by the fibromuscular capsule and lobulated. Each lobule was formed of secretory endpieces and ducts. The secretory endpieces were mucous and serous. However, the mucous type was predominant. The lining cells of the secretory endpieces expressed a positive reaction to alcian blue and Periodic acid Shiff. A series of duct system within the lobules and septa was seen. The scanning electron microscopic examination revealed that the secretory endpieces covered with granular secretory substance. Several crystals with sharp taper ends were seen around the secretory endpieces.

Anatomical and morphometric evaluation of the orbit, eye tunics, eyelids and orbital glands of the captive females of the South African painted dog (Lycaon pictus pictus Temminck, 1820) (Caniformia: Canidae)

“…In our study, the lacrimal gland of the South African Painted Dogs was located in the lateral canthus of the eye between the dorsal straight and lateral straight muscles in the dorsolateral angle of the periorbital located, which is similar other reported Canidae [21,44,87,[90][91][92]. It was triangular and light pink.…”

An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface

“…88 The morphological and histological features of the canine glands resemble the human lacrimal gland including distinct lobules and acini that provide serous and mucous secretions, as well as intralobular ducts that drain into small excretory tubules. 12,89 Likewise, an…”

“…Harderian gland is not present in the canine or human orbit. 12,19,89 However, two notable differences exist between species: (i) the combined volume of the two canine glands is smaller than the main lacrimal gland in humans (0.24 vs. 0.60 cm 2 ) 16,17 ; and (ii) the accessory lacrimal glands of Krause and Wolfring are absent in dogs (or not yet reported), presumably being consolidated through evolution into the single gland of the third eyelid. 90 These accessory glands account for 10% of the total lacrimal secretory mass in humans but their contribution to the overall tear secretion is negligible (1-2%).…”

“…In dogs, an orbital lacrimal gland and gland of the third eyelid contribute to 60%–70% and 30%–40% of the overall tear secretion, respectively 88 . The morphological and histological features of the canine glands resemble the human lacrimal gland including distinct lobules and acini that provide serous and mucous secretions, as well as intralobular ducts that drain into small excretory tubules 12,89 . Likewise, an Harderian gland is not present in the canine or human orbit 12,19,89 .…”

“…The morphological and histological features of the canine glands resemble the human lacrimal gland including distinct lobules and acini that provide serous and mucous secretions, as well as intralobular ducts that drain into small excretory tubules 12,89 . Likewise, an Harderian gland is not present in the canine or human orbit 12,19,89 . However, two notable differences exist between species: (i) the combined volume of the two canine glands is smaller than the main lacrimal gland in humans (0.24 vs. 0.60 cm 2 ) 16,17 ; and (ii) the accessory lacrimal glands of Krause and Wolfring are absent in dogs (or not yet reported), presumably being consolidated through evolution into the single gland of the third eyelid 90 .…”