Unusual features in the conjunctiva and cornea of the normal guinea-pig: clinical and histological studies.

Abstract

SUMMARY Clinical and histological studies of the outer eyes of newborn and adult female guineapigs were carried out together with histological studies of fetal eyes. Fine superficial corneal vessels, extending from the limbus, were seen in most newborn and adult eyes and were also present in histological preparations of fetal eyes. These vessels were therefore considered to be features of the normal guinea-pig eye. Masses of tissue composed of lymphoid cells, which were often organised into germinal centres, were found in the fornices of newborn and adult eyes. Smaller accumulations of lymphoid cells were found in fetal eyes, and this lymphoid tissue was therefore also considered to be a normal feature of the guinea-pig eye. In adult eyes mild but short-lived oedema or hyperaemia of the palpebral conjunctiva was quite common. There were no differences in the amounts of conjunctival cellular infiltration in these eyes compared with normal eyes, and these inflammatory changes were therefore not considered to be significant.

Investigations on the conjunctival goblet cells and the characteristics of the glands associated with the eye in chinchillas (Chinchilla Laniger)

“…Because of its histological appearance, the conjunctiva was divided into four zones. Several authors graded the conjunctiva of guinea pigs, 13–18 rats, 19 and mice 20 in a different way to ours; however, in the study by Gasser et al. , 9 the zoning system in guinea pigs was reported similar to ours.…”

The role of eye‐associated lymphoid tissue in corneal immune protection

“…The regular occurrence of follicles, most of which are secondary ones with a bright germinal centre indicating lymphoid cell proliferation after antigen contact, were found in the conjunctiva of species such as the guinea‐pig (McMaster et al. 1967; Dwyer et al. 1983), rabbit (Axelrod & Chandler, 1979; Franklin & Remus, 1984; Knop & Knop, 1996a), turkey (Fix & Arp, 1989), chicken (Fix & Arp, 1991) and monkey (Ruskell, 1995b).…”

Ocular Surface Disease in Rodents (Guinea Pigs, Mice, Rats, Chinchillas)

“…Guinea pigs have a remarkably low corneal sensitivity (or a high pressure threshold is needed to elicit a blink), replicated in 3 studies. 1,3,4 In these studies, the guinea pig was observed to have limited to no reflex tearing, which may be a component of the lack of corneal sensitivity ( Fig. 1, Table 1).…”

“…Fine superficial corneal neovascularization (usually extending from limbus axially to the first or second third of the cornea) has been reported as a normal finding in fetal, newborn, and adult guinea pigs. 1 However, a later confocal microscopy study did not confirm this. 2 Small palpebral conjunctival outpouchings were noted in the upper and lower fornices in almost all examined animals according to Dwyer and colleagues (1983), and were determined via histology to be masses of lymphoid tissue.…”

“…11 This had also been seen in a previous survey of guinea pigs. 1 It has been theorized that the corneal vessels and lymphoid tissue unique to guinea pigs eyes were an evolved strategy over increased blinking and discomfort seen in other animals. That being said, foreign bodies should still be taken seriously and treated promptly.…”