Vaginal histological changes of the baboon during the normal menstrual cycle and pregnancy.

BACKGROUND: A baboon, a non-human primate, is phylogenetically close to human and has been used to study in detail aspects of reproductive physiology that cannot be studied in humans for ethical reasons. OBJECTIVE: To determine the histological changes in baboon vagina associated with cyclic variations during normal menstrual cycle. SETTING: The experiments were carried out at Institute of Primate Research (IPR), Karen, Nairobi, Kenya. SUBJECTS: Nine adult healthy female olive baboons were used in this study. These baboons were monitored over a period of one year and found to have regular menstrual cycles. The vaginal biopsies were taken at different menstrual stages, fixed in 10% formalin and processed to evaluate histological changes. RESULTS: Observation of the histological sections of the biopsies by light microscopy showed that there were histological changes associated with cyclic variations in female olive baboon. During the luteal phase, menstrual phase and pregnancy the squamous epithelium was very thin. The layer gradually thickens throughout the proliferative phase and was thickest during the ovulation period. CONCLUSION: The changes in squamous epithelium suggest that the baboon vagina undergoes histological changes throughout the menstrual cycle which may be associated with hormonal variations. The data from this study also suggest that olive baboon is a good model for investigating possible effects of hormonal contraceptives on vaginal epithelium and the mechanism of female heterosexual transmission of HIV.

Evidence for expression of endogenous retroviral sequences on primate reproductive tissues and detection of cross-reactive ERVS antigens in the baboon ovary: a review.

OBJECTIVE: To review recent research findings on the specific expression of endogenous retroviral sequences (ERVS) in reproductive tissues and their possible physiological roles. ERVS have been implicated in several biological events such as induction of resistance to exogenous retrovirus invasion, involvement in placental trophoblast formation, sperm maturation and differentiation; and stimulation of local immunosuppression to protect the foetus from immunological attack. DATA SOURCES: Critical review of relevant articles and abstracts cited in international and local journals, literature searches on Medline and Medchem up to 2005. DATA SYNTHESIS: Retroviruses have been implicated in the induction of tumour and immunological disorders. Over the years, endogenous retroviruses (ERVs) and retroviral elements have been detected in the genome of many vertebrate species, including primates. The evidence for the presence of retroviruses in the primate tissues such as the placenta, ovary, breast, testis and epididymis has been documented using electron microscopic studies. Retrovirus-like particles were found budding from the basal membrane of syncytiotrophoblasts, as well as in tumour cell lines in embryonic carcinoma or teratocarcinomas. Apart from their pathological effects, recent evidence suggests that these ERVs may play useful roles in normal physiological events. RESULTS: Recent studies indicate the expression of endogenous retroviruses in the testis, epididymis, placenta and breast. However, limited data exist on the detection of ERVs in the ovary. Overall, the precise functions for ERVs in these tissues are not well understood. In the testis and epididymis, speculative functions may include among others spermatogenesis and/or sperm maturation (differentiation) whereas in placenta they are possibly associated with trophoblast fusion and locally induced immunosuppression to protect the foetus from immunological attack. Experiments in our laboratory have indicated restricted expression of retroviral antigens including baboon endogenous retroviral proteins (BERV), ERV-3, HIV-1 gp41 and HERV-K env in the baboon ovary. CONCLUSION: ERVs are specifically expressed in different mammalian reproductive tissues and may have unique physiological roles.

Effects of khat (Catha edulis) consumption on reproductive functions: a review.

OBJECTIVE: To review research findings on the effects of khat (Catha edulis) chewing on reproductive functions. DATA SOURCES: Retrieval and critical review of relevant articles and abstracts cited in international and local journals, literature searches on Medline and Medchem from 1961 to 2002. DATA SYNTHESIS: Analysis of published data and limited interviews of regular khat users revealed that khat chewing lowers libido in humans and may also lead to sexual impotence following long term use. In pregnant women, consumption of khat affects growth of foetus by inhibiting utero-placental blood flow and as a consequence, impairs foetal growth. CONCLUSION: Detailed studies on the effects of khat on reproduction are lacking. However, the limited available data reveal that chewing of khat has a negative impact on human reproductive health. Khat is genotoxic and has teratogenic effects on the foetus if regularly consumed by pregnant mothers. Since low birth weight is a well-established risk factor for both perinatal and young infant death, khat chewing during pregnancy may be one of the factors contributing to infant mortality in communities where khat is commonly chewed. Khat consumption affects the potency of male sexuality by affecting spermatogenesis and plasma testosterone concentration. However, the precise mechanisms by which khat may affect the male reproductive physiology have not been elucidated.