G. O Owiti

The Origin and Development of the Upper Lateral Incisor and Premaxilla in Normal and Cleft Lip/Palate Monkeys Induced With Cyclophosphamide

OBJECTIVE Cleft lip/palate (CLP) is a common human congenital defect in which the maxillary lateral incisors are often absent, malformed, and malpositioned. The present study was designed to examine the origin of the upper primary lateral incisor relative to the medial nasal process (MNP) and maxillary process (MP) fusion area and to the premaxillary/maxillary (incisive) suture in monkeys. METHOD Scanning electron microscopy, histology, skeletal staining, and drying techniques were used to study facial development in embryo and fetal monkey specimens. A teratogenic dose of cyclophosphamide was administered to pregnant monkeys prior to fusion of the MNP and MP and fetuses were examined for CLP. RESULTS Formation of the anterior maxilla involved fusion of the MNP and MP at stages 14-18. At stages 18-20, the palatal portion of the MNP had formed the medial and lateral incisive mounds. By stage 22, the upper primary lateral incisor has formed within the MP, lateral to the MNP/MP fusion area and to the ossifying premaxilla. Ossification of the premaxilla begins in the MNP and subsequently spreads laterally across the MNP/MP fusion area into the MP. Accordingly, the lateral incisor undergoes a complex positional shift (mainly medial) relative to the incisive suture both prenatally and postnatally and is finally located medial to the suture. Examination of the cyclophosphamide-induced CLP fetuses showed that the lateral incisor is located lateral to the alveolar cleft and does not shift medial to the incisive suture. CONCLUSION Understanding the origin of the lateral incisor (the tooth closest to the cleft) and the shift after its formation provides clues to high incidence of malformations and ectopia of this incisor in cleft patients.

Early placentation in the African green monkey (Cercopithecus aethiops).

Placentation in the green monkey (Cercopithecus aethiops) from gestational ages of 18-30 days was studied by light and electron microscopy. The placentae show many features in common with that of the rhesus monkey and other related macaques. Implantation is superficial and bidiscoid, and the placenta is classified as villous and hemomonochorial. Epithelial plaque formation and a moderate stromal reaction occur. Plaque cells are large, with massive deposits of glycogen and marginal pleomorphic dense bodies. Observations further support the concept that chorionic blood vessels, angioblastic and mesenchymal cells are not derived by delamination from cytotrophoblast. Capillary formation is by attachment of one or more mesenchymal cells and/or their processes. Embryonic blood was not observed in the villi until after day 22.

The effect of the anti-progestin RU 486 on early pregnancy in the long-tailed macaque (Macaca fascicularis)

The efficacy of various doses of RU 486 in terminating pregnancy before and after the luteal-placental shift (LPS) in the long-tailed macaque (Macaca fascicularis) was assessed through sonographic examination and measurements of steroid hormones and their metabolites. Intramuscular injection of 1.0, 2.5, 12.5, or 25.0 mg/kg was administered either from gestational day (GD) 15-18 (Group 1; N = 11) or GD 23-26 (Group 2; N = 9). The timing of treatment was determined by the detection of the preovulatory estrogen peak via daily urinary estrone conjugate (E1C) measurements. In Group 1, a 90.9% pregnancy loss was observed (10/11); seven animals aborted during GD 15-20, two animals indicated early embryonic death with retained gestational sacs, one animal aborted on GD 56, and one pregnancy was maintained. In Group 2, an 88.9% pregnancy loss was observed (8/9); eight animals aborted between GD 26-29, and one pregnancy was unaffected. Hormone profiles appeared to fall secondarily to the loss of trophoblast function. These results indicate: (a) RU 486 was more effective after the LPS; and (b) the primary effect of RU 486 appeared to be at the level of the products of conception.

Fetal membranes and placenta of the african green monkey (Cercopithecus aethiops)

SummaryThis study examined developmental changes in fetal membranes and placenta of Cercopithecus aethiops from a Carnegie developmental stage 12 embryo to nearterm fetuses. Ultrastructurally, yolk sac cells (endoderm and mesothelium) were similar to comparable stages in other primates. Endodermal cells had few apical microvilli, abundant rough-endoplasmic reticulum, electron dense mitochondria and dense bodies. In contrast, mesothelial cells were squamous with numerous microvilli, small mitochondria and a few short strands of rough endoplasmic reticulum. Amnion cells early in gestation were squamous with few microvilli, large glycogen deposits and poorly developed cytoplasmic components. Tight junctions and desmosomes held adjacent cells together. The basal surface was smooth and the basal lamina was distinct. As development proceeded the amniotic cells became cuboidal and possessed numerous microvilli. Cytoplasmic organelles were better developed and glycogen deposits increased by mid-gestation. A thick layer of microfibrils and collagen fibers was prominent below the basal lamina. Near-term, the glycogen had virtually disappeared and the amount of lipid droplets increased. Basal infoldings and podocytic processes and the extracellular matrix had increased. The smooth chorion consisted of pseudostratified columnar cells. Cells had short microvilli, numerous granules and vesicles of variable size and electron density in early gestation. With increasing age, amounts of granules and vesicles decreased, as the endoplasmic reticulum became prominent. The chorionic trophoblast was a continuous layer in mid-pregnancy and its cells had well-developed organelles and inclusions. Late in gestation, the trophoblastic layer became discontinuous and wide intercellular spaces and channels were present. In the placenta, the trophoblastic elements showed features characteristic of primate placenta.

Characterization of antigens expressed in normal baboon trophoblast and cross-reactive with HIV/SIV antibodies.

Electron microscopic studies have revealed the presence of endogenous retroviral (ERV) particles in normal primate placental tissues. These particles have ultrastructural similarities to type C retroviral particles and are mainly associated with the trophoblast. In normal human placental tissues, they have antigenic similarity with exogenous retroviruses, such as the human immunodeficiency virus (HIV), and may have a role to play in the regulation of cellular gene expression, syncytiotrophoblast formation or pregnancy-related immunosuppression. In this study, a panel of antibodies (polyclonal and monoclonal antibodies) against viral proteins (anti-HIV and anti-SIV) and endogenous retroviral (ERV) proteins were assessed by immunohistochemistry and immunoblotting, for their cross-reactivity with ERV particles isolated from normal baboon placental tissues. The antibodies (anti-HERV-K RT, anti-ERV3 env, anti-HIV-1 p17, anti-HIV-2 gp120) reacted positively with the syncytiotrophoblast and each antibody recognized one or two proteins of molecular weights (MW) 38, 58 or 64 kDa present in the baboon placental villous tissues and SIV-infected molt-4 Cl8 cells, but not in uninfected cells. The results of this study confirm the specific expression of retroviral cross-reactive antigens in normal baboon placental tissues and suggest placental cellular proteins may have antigenic similarity with those recognized by anti-HIV/SIV antibodies. The role of these retroviral-related proteins expressed at the maternal-fetal interface remain unclear.

Uterine gland microstructure in the pregnant and the non-pregnant lesser galago (galago senegalensis)

La histologia y ultraestructura de las glandulas uterinas de la galago menor (Galago senegalensis) fueron estudiadas en seis ejemplares (5 prenadas y 1 no prenada). Una parte de las glandula se fijo con Bouin y otra con glutaraldehido al 2,5% en tampon cacodilato 0,1 M. Una vision general de los principales resultados revelo que las glandulas uterinas en el utero no gestante son rudimentarias y escasas dentro de la mucosa. Al principio de la prenez (primer trimestre) las glandulas uterinas aparecen en racimos. En la ultima etapa de la prenez (tercer trimestre) las glandulas uterinas aparecen opuestas a las vesiculas corionicas. En las ultimas etapas de gestacion el epitelio glandular materno consiste principalmente en epitelio cilindrico simple. Las celulas tenian abundantes cisternas aplanadas en el reticulo endoplasmico rugoso, por lo general con una orientacion apico-basal. Sus nucleos tenian abundante eucromatina en relacion con la cantidad de heterocromatina. Tambien tenian un aparato de Golgi prominente bastante caracteristico de celulas que sintetizan proteinas. El plasmalema basal fue rechazado en repliegues que psoeen el efecto de aumentar el area de superficie a traves del cual los nutrientes podrian pasar desde la circulacion materna y son secretadas por las celula como histiotrofo. Hipertrofia fisiologica e hiperplasia de las glandulas uterinas se observaron con el avance de la prenez.

IMMUNOHISTOCHEMICAL LOCALIZATION OF RETROVIRAL-RELATED ANTIGENS EXPRESSED IN NORMAL BABOON PLACENTAL VILLOUS TISSUE

Abstract: Endogenous retroviral particles (ERVs) have been detected in the genome of all eukaryotes. They are generally non‐pathogenic except in mice where they have been found to induce tumors and immunological disorders. The ERVs have morphological features consistent with type‐C retroviral particles and are commonly expressed in normal placental villous tissues. ERVs may have a role in the regulation of placental gene expression, syncytiotrophoblast formation, or pregnancy‐related immunosuppression. In this study, well‐characterized antibodies (monoclonal and polyclonal antibodies) raised against retroviral proteins (anti‐HIV and anti‐SIV) and endogenous retroviral (ERV) particles were assessed for their cross‐reactivity (by using immunohistochemistry) with normal baboon placental and other adult tissues. The monoclonal antibodies to exogenous retroviral proteins (anti‐HIV‐2 gp120, anti‐HIV‐1 gp41, anti‐SIVmac p27, anti‐HIV‐1 RT, and anti‐HIV‐2 core protein) showed specific immunohistochemical reactivity with the syncytiotrophoblast. Antibodies to endogenous retroviral gene products (anti‐ERV3 env, anti‐HERV‐K RT, and anti‐HERV‐K env) also reacted in a similar manner and did not cross‐react with other adult tissues. These studies have shown that retroviral‐cross‐reactive proteins are expressed in baboon placental syncytiotrophoblast and may have a role to play at the feto‐maternal interface.