The Orbitofacial Glands of Bats: An Investigation of the Potential Correlation of Gland Structure with Social Organization

Abstract

The facial glands of bats are modified skin glands, whereas there are up to three different orbital glands: Harderian, lacrimal, and Meibomian glands. Scattered studies have described the lacrimal and Meibomian glands in a handful of bat species, but there is as yet no description of a Harderian gland in bats. In this study we examined serial sections of orbitofacial glands in eight families of bats. Much variation amongst species was observed, with few phylogenetic patterns emerging. Enlarged facial glands, either sudoriparous (five genera) or sebaceous (vespertilionids only) were observed. Meibomian and lacrimal glands were present in most species examined (except Antrozous), though the relative level of development varied. Two types of anterior orbital glands were distinguished: the Harderian gland (tubulo-acinar: observed in Rousettus, Atribeus, Desmodus and Miniopterus) and caruncular (sebaceous: observed in Eptesicus and Dieamus). The relative development of the nasolacrimal duct and the vomeronasal organ did not appear to be correlated with the development of any of the exocrine glands examined. There does, however, appear to be a correlation between the presence of at least one well developed exocrine gland and the level of communality and known olfactory acuity, best documented in Artibeus, Desmodus, and Miniopterus.

The Lack of Nasolacrimal Ducts in Plethodontid Salamanders?

“…Less reliance on pheromonal communication could potentially be a convergent feature because of similar environmental variables, but this hypothesis requires testing. To our knowledge, only primates (Rehorek and Smith, ) and bats (Rehorek et al, ) also variably possess nasolacrimal ducts, and turtles lack nasolacrimal ducts altogether (Hillenius and Rehorek, ).…”

Development of the nasolacrimal apparatus in the Mongolian gerbil (Meriones unguiculatus), with notes on network topology and function

“…Embryologically, there are two potential precursors for the AOG (at day 18) in the Mongolian gerbil, both of which originate from the anterior part of the orbit. Multiple prenatal anterior orbital glandular cords have been described in humans (Arends and Schramm, ), Antillean fruit‐eating bats (Rehorek et al, ), deer (Rehorek et al, ), squamate reptiles (Rehorek, ), and alligators (Rehorek et al, ). Although the fate of these cords is unknown in the bats (Rehorek et al, ), a different fate is reserved for each of the other three groups of animals described.…”

A re‐examination and re‐evaluation of salamander orbital glands

“…It is usually only a mucous secreting gland, although in turtles it appears to have some salt‐secreting ability (Chieffi Baccari et al, ). Although the lacrimal gland may occur in several different locations in the posterior orbital (outer canthus) region in tetrapods (e.g., Saint Girons, ; Rehorek et al, ), there is never more than one such gland at a time. Because there are no other glands that can confuse the situation, the lacrimal gland passes the test for conjunction (cf.…”