Localization of integrin subunits alpha 6 and beta 1 during somitogenesis in the long-tailed macaque (M. fascicularis).

The distribution of integrin subunits alpha 6 and beta 1, and the alpha 6 beta 1 integrin ligand, laminin, was examined during somitogenesis in developmental stages 11, 13, and 16 in the long-tailed macaque, using peroxidase immunocytochemistry. Within differentiating somites in stage 11, alpha 6 expression was observed in the sclerotome, basal surface of dermamyotomal cells adjacent to the basal lamina and on scattered cells throughout the dermamyotome. In further advanced somites in stages 13 and 16, alpha 6 immunoreactivity became restricted to the myotome. alpha 6 was expressed on mesenchymal core cells within the myocele of undifferentiated epithelioid somites and the ventromedial wall of somites commencing differentiation at each stage. beta 1 distribution resembled that of alpha 6 in stage 11 somitic tissue, however, it remained present on myotome and sclerotome cells in the later stages, and was also expressed on dermatomal cells in stage 16. Laminin immunoreactivity, while more intense and prevalent than alpha 6 and beta 1 in each stage examined, occurred on the same somite cell populations as the 2 integrin subunits. These results show a defined distribution of alpha 6 on somitic tissue, and suggest this integrin is involved in somite differentiation. They also support a possible role for alpha 6 in myoblast formation and migration. Overlapping of beta 1 and laminin immunoreactivity with that of alpha 6 further suggests that alpha 6 pairs with beta 1 as a functional heterodimer for laminin in defined somitic regions.

Ovarian and uterine lymphatic drainage in Australian flying-foxes (genus Pteropus, suborder Megachiroptera).

Ovarian lymphatics of flying-foxes were traced to determine if they could transport hormones directly from ovary to ipsilateral uterine horn, thereby stimulating the localised endometrial growth which is characteristic of these animals. Intra-ovarian injections of ink and serial histological sections did not reveal any such connection. All major ovarian lymphatics and those from the cranial tip of each uterine horn drain cranially, terminating in 1 or 2 lymph nodes lying caudal to the ipsilateral kidney. For much of their course, the major ovarian lymphatics run in the adventitia of the ovarian venous sinus. This sinus encloses the coiled ovarian artery, which provides the major blood supply to the cranial end of the ipsilateral uterine horn. Some fine ovarian lymphatics run in the adventitia of the coiled ovarian artery. The enclosure of the coiled ovarian artery by the ovarian venous drainage is thought to provide the main route for transfer of steroids from ovarian vein to ovarian artery and thence to ipsilateral uterine horn. The ovarian lymphatics described here do not bypass the vascular pathway but provide an additional route for counter- or cross-current transfer of ovarian steroids to the ovarian arterial supply to the uterus.

Localisation of glycoproteins and glycosaminoglycans during early eye development in the macaque.

The composition of the extracellular matrix (ECM) was examined in the developing lens and optic cup (stages 11-16) of the long-tailed monkey (Macaca fascicularis) using peroxidase immunocytochemistry. The glycoproteins, fibronectin, laminin, and collagen types I and IV, were consistently associated with basement membranes (BM) of ocular epithelia at all stages examined. Discontinuity of the optic cup BM was observed during the early stages of evagination (stages 11 and 12); the even distribution of all 4 components was reestablished by stage 13 when the optic vesicle is closely apposed to the thickened lens placode. While fibronectin was most predominant in the mesenchymal matrix, all 4 glycoproteins were observed to variable degrees in the periocular mesenchyme. Particularly strong glycoprotein reactivity was observed in the interspace between the invaginating lens vesicle and optic cup whereas no significant reactivity occurred within the lens, developing retina or future corneal epithelium. Two glycosaminoglycans, hyaluronic acid and chondroitin sulphate, had virtually identical widespread staining patterns in all ocular BM and throughout the periocular mesenchyme and adjacent epithelial tissues, including the lens and retina. The observed temporal and regional staining patterns suggest that these ECM components are morphogenetic factors in the macaque eye, facilitating the complex series of integrated tissue interactions, movements and shape changes during the earliest stages of lens and optic vesicle morphogenesis. The macaque offers a valuable model to study these interactions due to the prolonged period of ocular development which is morphologically identical to humans.

The ovarian-uterine vasculature in relation to unilateral endometrial growth in flying foxes (genus Pteropus, suborder Megachiroptera, order Chiroptera).

The ovarian-uterine vasculature was examined in three Australian species of flying fox (Pteropus scapulatus, P. poliocephalus and P. alecto). Vascular casts and histological sections were used to determine the relationship between the blood supply and the localized endometrial reaction, which occurs ipsilateral to the ovulating ovary. The ovarian artery coils extensively just cranial to the ovary, gives off a branch to the ovary and continues caudally as the major vessel supplying the cranial tip of the uterus, where it anastomoses with the smaller uterine artery. The coil of the ovarian artery is completely enclosed by a venous sinus that drains the cranial pole of the ovary. The ovary is heavily encapsulated, with primordial follicles restricted to the caudal pole; thus, the corpus luteum is completely internal and placed cranially, close to the coil of the ovarian artery. This arrangement would allow countercurrent or crosscurrent transfer of ovarian steroids from ovarian vein to ovarian artery and on to the cranial tip of the ipsilateral uterine horn. The steroids could thus reach high concentrations locally and generate localized endometrial growth. Cranial to the coil, the ovarian artery is enclosed in a venous sinus that derives from uterine as well as ovarian veins. This would allow countercurrent transfer of bioactive substances from uterus to ovary.

Characterization of the extracellular matrix during somitogenesis in the long-tailed monkey (Macaca fascicularis).

The composition of the extracellular matrix (ECM) associated with somitogenesis (stages 10-14) in the long-tailed monkey (Macaca fascicularis) was examined using peroxidase immunocytochemistry. A distinct temporal and spatial staining pattern was demonstrated for each component examined. Fibronectin (FN), laminin (LM) and hyaluronic acid (HA) were associated with the somite at each developmental stage, while no chondroitin sulfate (CS) staining was evident until stages 13/14. The basement membrane and matrix fibers linking the somites to the surrounding epithelia stained for FN, LM and HA. Localization of LM and HA between somite cells was observed at each stage, whereas FN and CS reactivity within the somitic tissue was only observed between sclerotome cells at stages 13/14. Whereas FN- and HA-positive fibers surrounded the unsegmented mesoderm, HA, and to a lesser extent LM, were located within the presomitic tissue. Comparisons are made with earlier studies conducted in rodent and avian embryos which indicate that these ECM components may play a regulatory role in primate somitogenesis.

Distribution of extracellular matrix components during early embryonic development in the macaque.

The distribution of fibronectin (FN), laminin (LM), hyaluronic acid (HA) and chondroitin sulfate (CS) were examined by peroxidase immunocytochemistry in long-tailed monkey embryos during the period of neural tube and notochord formation (stages 8-11). Reactivity for each component in the neuroepithelial basement membrane (BM) increased with advancing development. Discontinuous staining was observed in areas of epithelial-to-mesenchymal transformation, i.e. in dorsolateral sites of neural crest emigration and in the axial region of the primitive streak. The BM forming around the developing notochord also showed increased reactivity for FN, LM, HA and CS between stages 8 and 11. No staining occurred within the notochord. Stage-related increases in reactivity in the mesenchymal matrix was particularly notable for FN and HA which were ubiquitous throughout the mesoderm by stage 11. The results of this study are consistent with the proposed role of these components in maintaining epithelial integrity and providing a permissive substrate for cell migration during development. The observed temporal and regional staining patterns suggest that these glycoproteins and glycosaminoglycans are important morphogenetic factors in the macaque.