Potential candidate cells for constructing tissue-engineered lacrimal duct epithelium: a histological and cytological study in rabbits

Objective： Injury and deficiency of the lacrimal duct epithelium （LDE） can lead to a variety of lacrimal diseases. The purpose of this study was to characterize potential candidate cells for constructing a tissue-engineered LDE. Methods： Different areas of the conjunctiva and lacrimal duct tissue were removed from male adult New Zealand white rabbits for histological evaluation. Hematoxylin and eosin staining and immunohistochemical staining of cytokeratin AEI＋AE3, cytokeratin 4, Ki-67, and MUC5AC were observed by light microscopy. The surface morphologies of different epithelial tissues and cellular structures were examined using field-emission scanning electron microscopy and transmission electron microscopy. Epithelial cells were isolated from tissues and identified by specific markers. In vitro, proliferative ability and Western blot analyses of the proliferating cell nuclear antigen （PCNA） of different epithelial cells cultured in identical environments were investigated and compared. Results： Histologically, the epithelial specific markers, cytokeratin AEI＋AE3 and cytokeratin 4, were expressed in the conjunctiva epithelium and the LDE. Notably, highly proliferative cells stained with Ki-67 were concentrated under the epithelium in a dome structure of the posterior palpebral conjunctiva. Differentiated goblet cells were also found to a lesser extent in this region. Primary palpebral and fornical conjunctival epithelial cells （PFCECs）, bulbar conjunctival epithelial cells （BCECs）, and lacrimal duct epithelial cells （LDECs） were successfully separated from tissues. In vitro, rabbit PFCECs and LDECs grew faster and expressed more PCNA than BCECs. Conclusions： PFCECs are anatomically similar to LDECs. They also have similar morphological characteristics, immune phenotypes, and proliferation features. PFCECs are therefore potential candidate cells to replace LDECs in tissue engineering to treat lacrimal duct diseases.

Induction of follicular luteinization by equine chorionic gonadotropin in cyclic guinea pigs

The effects of equine chorionic gonadotropin （eCG） on follicular development and ovulation in cyclic guinea pigs were investigated by histological and immunohistochemical analyses. Three groups of guinea pigs （n=12） were administrated subcutaneously with saline, 20 or 50 IU of eCG, respectively, on cyclic Day 12 （Day 1=vaginal openings）. Ovaries were collected at 4 and 8 d after administration （6 animals per group each time）. The eCG administration induced significant and distinct morphological changes in the ovaries, as it promoted the luteinization of granulosa cells, but not follicular development. In addition, proliferating cell nuclear antigen （PCNA） and steroidogenic acute regulatory protein （STAR） were immunolocalized specifically in luteinized follicles. Our experiments together indicate that eCG administration can induce follicular luteinization but not superovulation in guinea pigs. The eCG in cyclic guinea pigs functions similar to that of luteinizing hormone （LH）, but not follicle-stimulating hormone （FSH）.