Nictitating Membrane Research Articles

Morphological examination of the visual system and orbital region in the red panda (Ailurus fulgens fulgens)

ObjectivesThe red panda is currently the only surviving member of the Ailuridae family in the Caniformia suborder. In this study, we provide data on anatomical, morphometric, histological and histochemical examination of the orbital region, eyelids, orbital gland, and eye tunics in two adult males Ailurus fulgens fulgens from the Wroclaw Zoological Garden, Poland.MethodsThe study involved morphometric analysis of the eyeball and selected accessory organs of the eye, along with analysis of the bony orbit, including its morphometry, macroscopic, and microscopic evaluation. Microscopic evaluation encompassed histological and histochemical staining, with the former involving hematoxylin & eosin (H&E), Movat pentachrome, picro-Mallory trichrome, Fontana-Masson, and the latter including PAS, AB pH 1.0, AB pH 2.5; AB pH 2.5/PAS, and HDI.ResultsThe upper (UE) and lower (LE) eyelids presented well-developed tarsal glands, sebaceous glands, and a characteristic simple alveolar gland (producing a mucous secretion). The palpebral part of the lacrimal gland was present. A single lymphoid follicle was observed only in the upper eyelids. The superficial gland of the third eyelid (SGTE) was a multilobar acinar complex that produces mucous secretion and is contained within the interlobular ducts of numerous aggregates of lymph nodes. The third eyelid (TE) was T-shaped and composed of hyaline tissue, containing CALT. The lacrimal gland (LG) also revealed a multilobar acinar complex that produced mucous secretion, with a single lymphoid follicle. The cornea consisted of 4 layers, as Bowman’s membrane was absent. The Vogt palisades composed of 7–10 layers of epithelial cells were demonstrated. The pupil was horizontally ovoid at rest (post-mortem). The sphincter pupil and the dilator pupil were well developed. Macroscopically, the tapetum lucidum appeared as a milky, non-opalescent crescent. Histologically, the choroidal tapetum lucidum cellulosum consisted of 5 to 9 layers of loosely packed oval cells. The retina showed a composition similar to that of terrestrial nocturnal carnivores.ConclusionsThe results of our research indicate that the anatomical features of the eye and orbital region in the red panda share similarities with those described in the Musteloidea clade, as well as the Canidae and Ursidae families.

Harderian Gland Development and Degeneration in the Fgf10-Deficient Heterozygous Mouse.

The mouse Harderian gland (HG) is a secretory gland that covers the posterior portion of the eyeball, opening at the base of the nictitating membrane. The HG serves to protect the eye surface from infection with its secretions. Mice open their eyelids at about 2 weeks of age, and the development of the HG primordium mechanically opens the eye by pushing the eyeball from its rear. Therefore, when HG formation is disturbed, the eye exhibits enophthalmos (the slit-eye phenotype), and a line of Fgf10+/- heterozygous loss-of-function mice exhibits slit-eye due to the HG atrophy. However, it has not been clarified how and when HGs degenerate and atrophy in Fgf10+/- mice. In this study, we observed the HGs in embryonic (E13.5 to E19), postnatal (P0.5 to P18) and 74-week-old Fgf10+/- mice. We found that more than half of the Fgf10+/- mice had markedly degenerated HGs, often unilaterally. The degenerated HG tissue had a melanized appearance and was replaced by connective tissue, which was observed by P10. The development of HGs was delayed or disrupted in the similar proportion of Fgf10+/- embryos, as revealed via histology and the loss of HG-marker expression. In situ hybridization showed Fgf10 expression was observed in the Harderian mesenchyme in wild-type as well as in the HG-lacking heterozygote at E19. These results show that the Fgf10 haploinsufficiency causes delayed or defective HG development, often unilaterally from the unexpectedly early neonatal period.

Clinical outcomes and learning curve of Tip-in endoscopic mucosal resection for 15-25mm colorectal neoplasms among non-experts.

Tip-in endoscopic mucosal resection (EMR) has a high en bloc resection rate for large colorectal neoplasms. However, non-experts' performance in Tip-in EMR has not been investigated. We investigated whether Tip-in EMR can be achieved effectively and safely even by non-experts. This retrospective study included consecutive patients who underwent Tip-in EMR for 15-25mm colorectal nonpedunculated neoplasms at a Japanese tertiary cancer center between January 2014 and December 2020. Baseline characteristics, treatment outcomes, learning curve of non-experts, and risk factors of failing self-achieved en bloc resection were analyzed. A total of 597 lesions were analyzed (438 by experts and 159 by non-experts). The self-achieved en bloc resection (69.8% vs 88.6%, P<0.001) and self-achieved R0 resection (58.3% vs 76.5%, P<0.001) rates were significantly lower in non-experts with <10 cases of experience than in experts, but not in non-experts with >10 cases. Adverse event (P=0.165) and local recurrence (P=0.892) rates were not significantly different between experts and non-experts. Risk factors of failing self-achieved en bloc resection were non-polypoid morphology (OR 3.4, 95% CI 1.6-7.3, P=0.001), lesions with an underlying semilunar fold (OR 3.6, 95% CI 1.6-7.3, P<0.001), positive non-lifting sign (OR 3.1, 95% CI 1.2-8.0, P=0.023), and non-experts with an experience of ≤10 cases (OR 3.6, 95% CI 2.1-6.3, P<0.001). The clinical outcomes of Tip-in EMR for 15-25mm lesions performed by non-experts were favorable.

WIDENING OF THE NIKTITAN MEMBRANE IN THE EYE OF DOMESTIC CATS WITH CHLAMYDIOSIS SUSPECT

Feline chlamydiosis or chlamydia is an infection caused by a bacterial organism. A local cat named Mio, male, orange and white, aged about 4 months, weighing 1.2 kg, had complaints of sneezing, red eyes and runny nose in the left eye since 2 weeks ago. The condition of the eye has gotten worse since a week ago with the white membrane covering the eyeball. Respiratory examination showed abnormal results, namely the case cat experienced sneezing and had a serous discharge. On examination the eye looks swollen and there is a mucopurulent discharge. The pupil reflex of the left eye is not visible because the nictitan membrane covers almost the entire eyeball. The Schirmer test showed that the case cat was producing excessive tears. Examination using an ophthalmoscope, the pupil of the cat's eye in the left case was not detected due to being covered by a shifting nictitating membrane. the fluorescen test showed a negative result, which means that there was no ulcer on the cornea. CBC examination results showed that the cat had leukocytosis and thrombocytosis. The case cat was diagnosed with dilation of the nictitating membrane and unilateral conjunctivitis with suspected chlamydiosis. Therapy is carried out by administering antibiotics, anti-inflammatory drugs, and vitamins. Evaluation on the 8th day after administration of therapy showed slightly improved results. In the left eye inflammation has started to improve. In addition, the mucus in the left eye also began to decrease. We recommend that treatment of case cats be continued for up to 3 weeks and a PCR test should be carried out so that the cause of infection in case cats can be known for sure.

Challenges in diagnosing canine spindle cell tumours using immunohistochemistry, illustrated by three nonpigmented malignant cases from the nictitating membrane

BackgroundNonpigmented malignant spindle cell tumours of the membrana nictitans are rare in dogs. In twenty-three years only three cases have been diagnosed in Scandinavia. This study describes the three cases of malignant tumours of the membrana nictitans recorded by the Eye Pathology Section, University of Copenhagen, Denmark, with reference to the clinical appearance and work-up, the treatment and prognosis, and the histopathological description including immunohistochemistry. The three cases are compared to previous publications on canine tumours of the nictitating membrane. We emphasize the importance of using protocols that are adapted to the specific species such as dogs. Opposite the human tissue responses, we even need more than one marker when diagnosing melanomas in dogs.ResultsThe dogs presented were an 8-year-old Dachshund, a 12-year-old Akita and a 14-year-old Shetland Sheepdog. All three dogs were entire females. All three nictitating membrane tumours developed on the right nictitating membrane as firm or multilobulated hyperaemic masses. Two of the tumours were macroscopically nonpigmented, the third being partly pigmented on the surface and ulcerated. According to the histopathology and for two of the cases immunohistochemistry with dog-adapted protocols the diagnoses included one hemangiosarcoma and two amelanotic melanomas. Tumour regrowth developed in all three cases and repeated resections were completed 1, 2 and 3 times, respectively, with recurrence experienced within 1.5 months − 3 years.ConclusionsNonpigmented malignant spindle cell tumours of the canine membrana nictitans are rare. Treatment of choice should be complete excision with a minimal histologic tumour-free distance and in case of a recurrence a full resection of the nictitating membrane. We strongly recommend a dog-adapted protocol for immunohistochemistry.

Enucleation of Bulbus Oculi in Domestic Cats Patients with Orbital Tumors

The eye is an essential organ for living things, as one of the five senses of the eye is very vulnerable to infectious or non-infectious diseases. The orbital tumor is one of the disorders in the cat's eye that can attack the eye muscles, nerves, and lacrimal glands. This study aims to diagnose and treat the enucleation of bulbus oculi in domestic cats and patients with orbital tumors. This activity was carried out at the Veterinary Practice "Drh. Juliadi Ramadhan, M.Si." Jl. Payakumbuh-Lintau No. 12 Regency 50 City, West Sumatra Province. The results showed that one of the treatments for orbital tumor cases can be done by enucleation of the oculi bulk. This operation uses a subconjunctival method to remove the eye, the nictitating membrane, and a little eyelid by minimizing the removal of extraocular muscle tissue. After surgery, intense treatment is carried out by maintaining the sanitation of the cage and administering anti-inflammatory drugs, antibiotics, and vitamins.

Ontogenesis of the Mouse Ocular Surface Lymphatic Vascular Network.

Ocular lymphatic vessels play major physiological role in eye homeostasis and their dysfunction can contribute to the progression of several eye diseases. In this study, we characterized their spatiotemporal development and the cellular mechanisms occurring during their ontogenesis in the mouse eye. Whole mount immunofluorescent staining and imaging by standard or lightsheet fluorescence microscopy were performed on late embryonic and early postnatal eye mouse samples. We observed that the ocular surface lymphatic vascular network develops at the early postnatal stages (between P0 and P5) from two nascent trunks arising at the nasal side on both sides of the nictitating membrane. These nascent vessels further branch and encircle the whole eye surface by sprouting lymphangiogenesis. In addition, we got evidence for the existence of a transient lymphvasculogenesis process generating lymphatic vessel fragments that will mostly formed the corneolimbal lymphatic vasculature which further connect to the conjunctival lymphatic network. Our results also support that CD206-positive macrophages can transdifferentiate and then integrate into the lymphatic neovessels. Several complementary cellular processes participate in the development of the lymphatic ocular surface vasculature. This knowledge paves the way for the design of new therapeutic strategies to interfere with ocular lymphatic vessel formation when needed.

The Various Ways in Which Birds Blink

There has, to date, been no systematic study of the various ways in which birds blink. Digital video recordings were made, and studied using still frames, of 524 bird species, mainly in zoos but also in the wild. Videos on 106 species from various sites on the internet were studied, some of which we had also videoed, giving a total of 591 (out of a possible 10,000) species from all 43 orders and 125 (out of a possible 249) families. Digital video recordings were also made of 15 (out of a possible 24) species of crocodile. Three types of blink were observed in birds: (1) Nictitating membrane blinks were rapid and brief (phasic) and occurred mainly on head movement. (2) Upper lid blinks were seen in parrots, owls, pigeons and some others. These were also rapid and brief and accompanied nictitating membrane blinks. (3) Lower lid blinks were slow and sustained (tonic) and occurred with drowsiness and preening. Nictitating membrane blinks and lower lid blinks were seen in crocodiles but not upper lid blinks. Globe retraction, where the eyeball is pulled into the orbit of the skull during a blink, was seen in crocodiles but not birds. Phasic blinks remove debris and moisten the cornea, essential for allowing oxygen to diffuse into the cornea, which has no blood supply. Tonic blinks are probably mainly protective. The orders of birds which have upper lid blinking are not closely related and this feature is probably the result of convergent evolution.

Follicular conjunctivitis in dogs: A retrospective study (2007-2022).

To evaluate the incidence, clinical features, treatment, and outcome of canine follicular conjunctivitis (CFC). Medical records of dogs diagnosed with CFC were reviewed. Data recorded included signalment, duration of clinical signs and treatment details prior to presentation, concurrent ocular/systemic diseases, ocular clinical signs, cytology, treatment, follow-up, and outcome. Blepharospasm, signs of self-trauma, hyperemia, chemosis, ocular discharge, and follicle location and severity (0.5-4) were retrospectively evaluated. Based on severity, treatment consisted of topical 0.1% diclofenac or 0.1% dexamethasone sodium eyedrops. Dogs were classified into young (YD < 18 months) and adult (AD ≥ 18 months). One hundred and fifty-three dogs (276 eyes) were included in the study: 83YD (54%) and 70AD (46%). Males and bilateral disease were over-represented in both groups. Severity was associated with young age (p = .032) and bilaterality (p = .025), and not with dermatological diseases (p > .05). No differences in follicular location were observed except for more frequent involvement of the nictitating membrane (MN) in YD (p = .02). Response to treatment was faster in AD (p = .001), with complete resolution in 80.6% of the eyes (100/124) at 1 month. YD treated with diclofenac showed faster resolution than those treated with 0.1% dexamethasone (p = .009). Although CFC is a bilateral ocular disease occurring at any age, the clinical presentation is influenced by age. Follicular conjunctivitis in adult dogs is less sever, less commonly affects the NM, and responds more quickly to topical treatment. One month of topical diclofenac may be adequate for mild cases, and 1 month of topical 0.1% dexamethasone is recommended as initial therapy for moderate to severely affected cases.

Treatment of descemetocele with deep keratotomy combined with a nictitating membrane flap in a dog

A 10-year-old, spayed female, Maltese dog presented with a 2-day history of severe left eye squint. Slit-lamp biomicroscopy showed a deep corneal defect stained into a doughnut shape together with hypopyon in the anterior chamber. Based on these results, a diagnosis of descemetocele and uveitis in the left eye was made. Deep keratotomy combined with a nictitating membrane flap effectively resolved the descemetocele without complications. The surgical procedures performed on this patient were easy and effective, and could be used as an alternative to graft surgery for descemetocele treatment.

Microdissection of the Rodent Eye.

The ocular micro-dissection of the rodent eye involves the segmentation of the enucleated eyeball with the attached nictitating membrane, or third eyelid, to obtain the anterior and posterior eyecups. With this technique, the sub-parts of the eye, including the corneal tissue, neural tissue, retinal pigment epithelial (RPE) tissue, and lens, can be obtained for wholemounts, cryo-sectioning, and/or single-cell suspensions of a specific ocular tissue. The presence of the third eyelid presents unique and significant advantages, as it benefits the maintenance of the orientation of the eye, which is important for understanding eye physiology following any localized intervention or in studies involving ocular analysis relating to the eye's spatial topography. In this method, we enucleated the eyeball at the socket along with the third eyelid by carefully and slowly cutting through the extraocular muscles and severing the optic nerve. The eyeball was pierced through the corneal limbus using a microblade.The incision was used as the point of entry, allowing for cutting along the corneal-scleral junction by inserting micro-scissors through the incision point. Small and continuous cuts along the circumference were made until the cups separated. These could be further dissected by gently peeling the translucent layer of the neural retina using Colibri suturing forceps to obtain the neural retina and RPE layers. Further, three/four equidistant cuts were made from the periphery perpendicularly to the optic center until the optic nerve was reached. This opened the hemispherical cups into a floret shape so that they fell flat and could be easily mounted. This technique has been used in our lab for corneal wholemounts and retinal sections. The presence of the third eyelid delineates the nasal-temporal orientation, which allows for the study of various cell therapy interventions post-transplantation and, thus, the targeted physiological validation vital for visualization and accurate representation in such studies.

Anatomy, Physiology, and Disorders of the Spectacle, Subspectacular Space, and Its Lacrimal Drainage System in Squamates.

Various squamate species have completely fused eyelids that make up a transparent spectacle. The spectacle is a continuation of the integument that is renewed with each shedding cycle and creates a narrow subspectacular or corneospectacular space that is filled with lacrimal fluid. The latter is considered as the analogue of the conjunctival sac in other vertebrates. Almost all reptiles that have a spectacle lack a nictitating membrane, bursalis muscle, and lacrimal glands. The lacrimal fluid in the subspectacular space is secreted by the Harderian gland. The features of the spectacle and its lacrimal drainage system are an illustration of the enormous variation of the morphological adaptations that are seen in reptiles and one of the most distinguishable traits of snakes and most gecko species. Whereas ocular disease in squamates with a spectacle is infrequently seen in practice, disorders of the spectacle and the subspectacular space are commonly encountered. In order to apply an adequate diagnostic and therapeutic approach for these conditions, a sound knowledge and understanding of the anatomical and physiological peculiarities of the spectacle, subspectacular space, and lacrimal drainage system are fundamental.

Systemic oxalosis in a free-ranging green turtle (Chelonia mydas)

A female juvenile green turtle (Chelonia mydas), found alive in Guanabara Bay, Rio de Janeiro, Brazil, was weak, dehydrated and cachectic, with a healed fracture in the caudal portion of the carapace. Despite supportive treatment, the animal died after 9 days. At necropsy the main lesions were pallor of visceral organs, arthritis and deposits of whitish granular material in the wall of large arteries and the trachea. Histopathological analysis revealed mild to severe deposition of crystals, consistent with calcium oxalate, in both kidneys and the spleen, heart, small intestine, pancreas, thymus and salt gland, as well as bacterial meningitis, septic arthritis, spirorchidiasis and a fibropapilloma on the nictitating membrane. The main pathological findings were suggestive of septic shock, mainly due to the bacterial meningitis and septic arthritis, with systemic oxalosis and spirorchidiasis as contributing lesions. Although renal oxalosis has been described in green turtles as an incidental finding, presumably due to ingestion of oxalate-containing plants, this turtle had an unusual systemic deposition of oxalate crystals.

Colonic Anisakiasis.

A 75-year-old man with hypertension, who was otherwise healthy, underwent a surveillance colonoscopy 1 year after a polypectomy. He had no specific symptoms, and his vital signs were normal. The examination showed an Anisakis larva invading the mucosa of the proximal ascending colon, where a semilunar fold was edematous and thickened with a small erosion on the inserted site (Figure A). Magnifying endoscopy with narrow-band imaging revealed a small whitish elongated spot (the ventricle, an organ located between the esophagus and the intestine of Anisakis larva), which was more clearly visible than with conventional white-light endoscopy (Figure B).

Офтальмологические проявления эндокринных заболеваний

The review provides a detailed description of ophthalmic disorders associated with the most common endocrine diseases — diabetes mellitus, hypo- and hyperthyroidism, chronic adrenal insufficiency, Cushing syndrome, and obesity. Specific characteristics of ocular disorders co-occurring with these diseases are highlighted in the article. In diabetes mellitus, there is a lesion of both the periorbital region — inflammatory processes of the eyelids and conjunctiva, xanthelasm of the eyelids, and intraocular structures — the retina, macula, lens and cornea. Ophthalmological changes in thyroid pathology are manifested by a combination of various "ocular" symptoms, the most famous of which are exophthalmos, dilation of the ocular slit, eye shine, convergence disorder. However, the first complaints of patients may be unstable diplopia, swelling of the eyelids (mainly in the morning), a feeling of "clogging", dryness, lacrimation and/or photophobia, spontaneous retrobulbar pain, pain when moving the eyes, redness of the eyelids, conjunctival injection, redness and swelling of the semilunar fold and lacrimal meat, hyperpigmentation of the eyelids — a symptom Jellineka, swelling and meniscus-like drooping of the eyelids are a symptom of a Singer. Some endocrine diseases may cause symptomatic arterial hypertension, e.g. Cushing disease (syndrome), primary hyperaldosteronism (Conn's disease), acromegaly, and pheochromocytoma. Early signs of the above diseases may include eye disorders which develop prior to other manifestations due to the onset of hypertensive retinopathy. The adequate assessment of the disorders of eyes and paraorbital tissues in patients with endocrine diseases may facilitate more accurate diagnosis and timely treatment. The publication could potentially benefit ophthalmologists, therapists, endocrinologists, pediatricians and general practitioners. Keywords: ophthalmic manifestations, diabetes mellitus, hyperthyroidism, hypothyroidism, adrenal insufficiency, endocrine diseases. For citation: Gazdanova A.A., Knyazeva S.A., Marakhovskaya A.A., Protopopova Yu.V., Sedova A.A., Rakhimov J.B., Salmanov A.F., Magomedova S.A. Ophthalmic manifestations of endocrine diseases. Russian Medical Inquiry. 2023;7(9) (in Russ.). DOI: 10.32364/2587-6821-2023-7-9-4.

Manajemen Bedah Prolaps Membran Niktitan pada Anjing Beagle di DNA Animal ClinicBogor

An 11-year-old female Beagle dog weighing 18 Kg was brought to the clinic with redness discoloration in her right eye, a cherry like lump, and ocular discharge. Based on the clinical signs, the diagnosis was a prolaps of the nictitating membrane or “Cherry Eye” with a fausta prognosis. The treatment was a surgery using the Morgan Pocket method to maintain the mobility of the nictitating membrane and lymphoid tissue. The postoperative therapy given was the anti-inflammatory drug meloxicam 0.2 mg/kg once a day orally and gentamicin eye ointment (Genoint 0.3% Eye Oint) topically twice a day. Five days after the surgery and treatment, the dog's eyes had improved, and there was no lump observable

Surgical Treatment of Nictitans Membrane Eversion in Dogs

The presented study is the first retrospective evaluation of the scrolling of the third eyelid in a total of 44 dogs referred to the Istanbul University-Cerrahpaşa, Faculty of Veterinary, Department of Surgery between 2012 and 2021 with a sudden onset of an ocular mass in the medial canthus with epiphora and conjunctival hyperemia. The clinical appearance of the patients, the treatment procedures applied, and the results were examined. A complete ophthalmological inspection revealed the cartilage eversion of the nictitating membrane in sixteen patients (24 eyes) due to the scrolling of the third eyelid and cartilage eversion accompanied by a prolapsed gland in twenty-eight patients (32 eyes). Cartilage eversion was treated by the resection of the defected cartilage portion. In cases with prolapse of the nictitans gland accompanying cartilage eversion, the Morgan pocket method was applied to reposition the prolapsed gland by resectioning the rotating cartilage. In conclusion, -taking into account the potential effect of breed, age, and gender predispositions- the therapeutic approach followed revealed satisfactory results in maintaining the functional capacity of the third eyelid in dogs with cartilage eversion of the nictitating membrane and hyperplasia of the nictitans gland.

Conventional versus hybrid knife endoscopic submucosal dissection in large colorectal laterally spreading tumors: A propensity score analysis.

Colorectal endoscopic submucosal dissection (CR-ESD) has become a promising treatment for laterally spreading tumors (LSTs), but is accompanied by great challenges. This study aimed to evaluate the efficacy and safety of CR-ESD with a hybrid knife, versus the conventional technique for LSTs ≥30 mm in diameter, and analyze the risk factors for piecemeal resection and perforation. Patients eligible for CR-ESD were divided into two groups according to the use of the hybrid knife (HK group) or the use of the conventional technique, with an interchange of injection and hook knife (C-group). We performed propensity score matching (PSM) to compare the HK group and the C-group. Risk predictors for perforation and piecemeal resection were identified. PSM identified 61 (132 patients) and 61 (129 patients) patients in the C-group and the HK group, respectively. Resection speed was significantly faster in the HK group than in the C-group (18.86 vs. 13.33 mm2/min, P < 0.001). The rate of knife exchange was significantly lower in the HK group than in the C-group (1.6% vs. 49.2%, P < 0.001). Multivariate analysis revealed that unfavorable locations, including the splenic flexure, hepatic flexure, or cecum, were predictive of piecemeal resection. The presence of severe fibrosis and a semilunar fold were independent risk factors for perforation. : The use of a hybrid knife appears to increase CR-ESD resection speed. The indicators for piecemeal resection or perforation in CR-ESD identified herein might help to assess the technical difficulties of CR-ESD.

Orbital soft tissues, bones, and allometry: Implications for the size and position of crocodylian eyes.

Although the visual system of crocodylians has attracted interest regarding optical parameters and retinal anatomy, fundamental questions remain about the allometry of the eyeball and whether such scaling is the same across all crown groups of crocodylians. In addition, anatomy and identities of adnexal soft tissues that interact with the visual system are not well understood in many cases. We used contrast-enhancing iodine stain and high-resolution micro-computed tomography to assess the anatomy of orbital soft tissues, including extraocular muscles and glands, in crocodylians. We also used regression analysis to estimate the allometric relationship between the bony orbit and eyeball across Alligator mississippiensis and Crocodylus niloticus for the first time. Results revealed tight, negatively allometric relationships between the bony orbit and eyeball. Notably, the eyes of C. niloticus were larger for a given orbit size than the eyes of A. mississippiensis, although the slope of the relationship was no different between these two crown crocodylian groups. Among the findings from our anatomical study, new details were uncovered about the homologies of muscles of the abducens complex. In particular, M. rectus lateralis of crocodylians is revealed to have a more complex form than previously appreciated, being adhered to the tendon of the nictitating membrane, which may be apomorphic for Crocodylia. Our calculation of the orbit-eyeball allometric relationship and study of the adnexal soft tissues of the crocodylian visual system, in combination with previous work by other teams in other crown saurian clades, is a critical, formerly missing, piece in the Extant Phylogenetic Bracket for restoring the visual apparatus of extinct crocodyliforms and other archosauriform groups.

Anatomical, scanning electron microscopy, histological and histochemical studies of the orbital glands of the Egyptian agama Trapelus mutabilis

BackgroundThe orbital gland of the group agama (Agamidae) is not well-studied. Here is a first description of anatomical and histological studies on the orbital gland of the Egyptian agama Trapelus mutabilis.ResultsThe Harderian gland (HG) of the Egyptian agama is well-developed, with a tongue shape, appearing whitish in color, and reaching approximately 1.47 mm in length. The gland can be divided into head and tail regions and lies at the medial corner of the orbit ventral to the ventralis oblique muscle and dorsal to the medialis rectus muscle. Secretory product of the HG is released into the conjunctival fornix, which is deep into the nictitating membrane. The HG is a compound tubuloacinar type, consisting of columnar and pyramidal glandular cells with rounded nuclei and lumina that are variable in size and containing pigments in the connective tissue capsule that envelops the tail portion of this gland. The glandular cells of the HG react positively to periodic acid-Schiff (PAS) and alcian blue staining at pH 2.5. In contrast, lacrimal gland (LG) of Egyptian agama is a reduced mucous gland that appears whitish in color, opens on the surface by numerous orifices at the base of nictitating membrane, and reaches approximately 0.1 mm in length. The lacrimal gland is composed of a simple tubulo-acini of columnar cells with narrow lumen and basal oval-shaped nuclei and exhibits a weak response to PAS but a strong response to alcian blue at pH 2.5.ConclusionsMorphology of LG and HG isn't impacted by features of the orbit, such as the existence or absence of nictitating membrane and/or fixed or movable eyelid. The small size of the LG of the Egyptian agama does not affect the performance of its main function in lubricating the surface of the cornea. The pigmentation envelope of the HG of the Egyptian agama allows heat to be absorbed in order to increase its secretion activity, thereby increasing the protection of the eyes against mechanical damage. Finally, both orbital glands may play a secondary function in digestion via indirect connection with the oral cavity.