The meibomian glands of the marmoset (<i>Callithrix jacchu</i><i>s</i>)

Characterization of Meibomian gland innervation in the cynomolgus monkey (Macaca fascicularis)

“…The terminals contain abundant small agranular vesicles and several large granular vesicles. Since small agranular vesicles are characteristic storage sites of acetylcholine (Gordon-Weeks 1988), this findings is consistent with histochemical observations of a dense acetylcholinesterase-positive nervous network around monkey Meibomian glands (Montagna and Ellis 1959;Miraglia and Gomes 1969). Small granular vesicles that are usually regarded as diagnostic for adrenergic nerves (Gordon-Weeks 1988) have not been observed, although enzymes involved in catecholamine synthesis, TH and DBH, have been identified in some varicose axons associated with Meibomian acini.…”

“…In several species, electron microscopy has demonstrated nerve terminals near Meibomian acini (Leeson 1963;Jester et al 1981). Many of these terminals stain for acetylcholinesterase and may be cholinergic in nature (Montagna and Ellis 1959;Miraglia -specific, cytoplasmic, al. (1979), 3 Grunditz et al (1986), 4 Larsen et al (1992, 5 Gul-ubiquitin carboxyl-terminal hydrolase (Wilkinson et al 1989) and Gomes 1969), but varicose axons immunoreactive for vasoactive intestinal polypeptide (VIP) have also been observed in close vicinity to Meibomian glands in a considerable number of species (Uddman et al 1980;Hartschuh et al 1984;Fan and Smith 1993).…”

Cell size and nucleo‐cytoplasmic ratios of meibocytes in the anterior acini of the upper eyelid Meibomian glands in rabbits

“…Over a few days, labeled cells could be seen toward the center of the acini, a migration that was considered to reflect mitoses and multiplication of the cells associated with differentiation of the acini. From studies on primate meibomian glands, it was noted that the peripheral cells in the acini were smaller and had an elliptical‐shaped nucleus while more centrally located differentiated (mature) cells were larger and had a round nucleus, and this perspective is also given, along with a schematic diagram with the nuclei having similar sizes . It has, however, also been noted that in the largest hypermature meibocytes, the cell nuclei change to a ‘pyknotic’ appearance, perhaps with those cells with pyknotic nuclei being found close to the ductules of the gland .…”

“…From studies on primate meibomian glands, it was noted that the peripheral cells in the acini were smaller and had an elliptical‐shaped nucleus while more centrally located differentiated (mature) cells were larger and had a round nucleus, and this perspective is also given, along with a schematic diagram with the nuclei having similar sizes . It has, however, also been noted that in the largest hypermature meibocytes, the cell nuclei change to a ‘pyknotic’ appearance, perhaps with those cells with pyknotic nuclei being found close to the ductules of the gland . This change could reflect the last aspect of the acinar function in that the contents change into the meibum secretion, a transformation referred to as ‘degenerating cells’, ‘decomposition’, or ‘disintegration’, with it being implied that this process starts at the center of the acini .…”

“…The actual secretory nature is not evident in such clumps with the units seen to have a relatively amorphous content such that the individual cells (meibocytes) are not uniformly evident. In other sections, perhaps at slightly higher magnification, some meibocyte nuclei can be visible, and just sometimes the individual meibocytes with their cell borders can be seen . The cells seen, however, do not have any obvious organization and so better sectioning and viewing methods as well as objective assessments are needed to underpin histopathological diagnoses of gland dysfunction.…”