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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 143-151 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Methyl methacrylate corrosion casts were made of the blood-vascular system of the lingual salt glands of the estuarine crocodile, Crocodylus porosus, and examined with light and scanning electron microscopy. The 28-40 individual salt glands, each opening separately via a single pore onto the dorsal surface of the tongue, are supplied by a pair of lingual arteries. Each gland is richly vascularized and is composed of 14-20 lobular sub-units, each having a dense network of capillaries. The blood flow in each gland is from the centre to its periphery, opposite to the direction of the flow of secretions in the ducts of the gland. The main collecting duct leading from the gland to the external pore was well vascularized. The blood supply to the glands of juvenile crocodiles raised in 20‰ salt water was more dense than in freshwater and, from cast masses, had a three-fold greater vascular volume. This study provides the first evidence which shows that the salt glands of crocodiles are morphologically labile and can adapt to the environmental salinity. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 2
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Ova were removed from donors 63-68 hours after ovulation and placed in the uteri of pseudopregnant recipients of the same pregnancy age. In transfers of ova from young (2 1/2-6 month) to old (14-18 month) golden hamsters, only 8.3% developed into term fetuses. From old donors to young recipients, 4.5% of ova developed to term fetuses. In transfers of ova from young donors to young recipients, 49.2% of ova developed into term fetuses. There was no significant difference in percentage of fetal development between the two groups containing old females. The difference between these and the control (young to young) group was highly significant.There was a significantly lower number of ova recovered from old donors. At time of transfer, over one-sixth of the ova from old donors consisted of only one to four cells. At seven and one-half days, embryos developing from ova of old donors in uteri of young recipients were retarded and malformed.It is concluded that while the uterine environment in old hamsters appears inadequate to foster normal fetal development, there are also fewer ova ovulated in old females and these ova more frequently develop abnormally.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The first statistically significant decline in the mean number of young born to female golden hamsters occurred in the fourth litters. The decreased size of fifth litters was highly significant and few females bore six litters.Hamsters unilaterally ovariectomized at 30 days of age had a significantly lower number of litters containing live young during their lifetime. Despite increased unilateral ovulaton, they bore less than half as many total young per female as intact controls and fetal resorptions and stillbirths occurred at an earlier age.The results of matings during the period of reproductive decline were observed in females from the age of ten months until death or sacrifice at an advanced age. Final litters contained few young, some born dead. One or two subsequent pregnancies were of term length but all conceptuses were resorbed. Few females beyond 15 months of age had implantation sites and most of these resorbed. Regular four day estrous cycles continued until a terminal illness and matings resulted in pseudopregnancy. Blastocysts were found at four and one-half days of gestation in some old females but not at 6 to 8 days. Failure of implantation appeared to be due to an inadequate uterine decidual reaction in the old animals.It appeared from the above observations that decreasing uterine adaptability limited reproductive capacity in aging hamsters.
    Additional Material: 3 Ill.
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  • 4
    ISSN: 0730-2312
    Keywords: avian embryo ; peripheral nervous system ; neural crest ; cell-adhesion ; cell migration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The peripheral nervous system derives mainly from the neural crest both in the head and trunk. Using markers such as fibronectin (FN), neural cell-adhesion molecule (NCAM), the nuclcolar marker for quail cells in chimaeric embryos, and NC-1, a monoclonal antibody specific to crest cells and their neural derivatives, we have attempted to reconstruct the processes that lead to the formation of peripheral ganglia. Our observations allow us to propose a model of the formation of ganglia based on morphogenetic movements and on variations of crest cell adhesiveness. In most cases, crest cells migrate in morphologically defined and transient pathways that lead them to their final site of arrest; these pathways are always associated with FN, which appears necessary for crest cell attachment and movement in vitro. The directionality of crest cell migration is probably dictated by the cells' motile properties and population pressure in restricted areas suitable for cell movement. The disappearance of the pathways and of the substrate necessary for migration while the population is rapidly dividing may be responsible for the aggregation of crest cells in the case of the sensory ganglia. To the contrary, the aggregation of crest cells into autonomic ganglia (sympathetic, enteric, aid ciliary ganglia) does not seem to obey the same rules, no disappearance of the substratum or of the pathways being obvious; rather, their formation seems correlated with the de novo synthesis of adhesive molecules such as NCAM.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 68 (1998), S. 427-435 
    ISSN: 0730-2312
    Keywords: α2-macroglobulin ; albumin ; placenta ; zinc ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have investigated the binding and internalization of α2-macroglobulin and serum albumin by human placental syncytiotrophoblast cells in vitro. The time course (obtained at 4°C) of α2-macroglobulin binding indicated that an equilibrium was reached after 4 h. The binding of 125I-labelled α2-macroglobulin to syncytiotrophoblast cells was competitively reduced in the presence of excess unlabelled α2-macroglobulin. When the concentration-dependence of binding was examined over a wide concentration range, non-linear regression analysis yielded a Kd of 6.4 nM. In the case of albumin, binding was weak and ligand dissociated from the cell surface during aqueous washing making it impractical to analyze the binding reaction. In other experiments, syncytiotrophoblast cells were incubated with 125I-labelled α2-macroglobulin at 37°C. Under these conditions, trypsin-resistant cell-associated radioactivity increased with time consistent with ligand internalization. 125I-Labelled-ligand was internalized with a t1/2 of about 5 min. After a lag period some radioactivity was released back into the incubation medium. When measured at times up to 210 min, this was found to consist of mostly TCA-precipitable material that had been lost from the cell surface. However, when the incubation was extended to 24 h, almost 15% of the initial cell-associated radioactivity was released to the extracellular medium as TCA-soluble material, consistent with a slow rate of ligand degradation. The specific binding of 65Zn-labelled α2M was similar to that of the 125I-labelled ligand and trypsin-resistance measurements provided evidence of α2M-mediated 65Zn uptake. These results support a role for syncytiotrophoblast in the metabolism of α2-macroglobulin during pregnancy and are also consistent with a role for α2-macroglobulin in the maternal-fetal transport of zinc. J. Cell. Biochem. 68:427-435, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 65 (1997), S. 460-468 
    ISSN: 0730-2312
    Keywords: placenta ; planar-polar compounds ; hCG ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Dimethyl sulfoxide (DMSO) exerts a number of biological effects, the most frequently cited being induction of cell differentiation. The compound also increases invasiveness and metastatic potential. In contrast to the many reports of DMSO-induced cell differentiation, we report here that DMSO inhibits the morphological differentiation of human cytotrophoblast cells to syncytiotrophoblast, as revealed by immunofluorescence staining for desmosomal protein and nuclei. Cytotrophoblast cells treated with DMSO under differentiation-inducing conditions remained mononucleated with intense desmosomal staining. The effect was dose dependent, with a maximal effect seen at 1.5% DMSO. Concentrations of ≤0.5% had no effect and concentrations 〉2% were cytotoxic. In addition to these morphological changes, DMSO inhibited secretion of human chorionic gonadotropin in a dose-dependent manner. At a concentration of 1.5%, DMSO inhibited secretion by 70%. If cytotrophoblast cells were cultured in the presence of DMSO and then switched to DMSO-free medium, they proceeded to differentiate normally. While the precise mechanism of action remains unknown, judicious use of DMSO may be a useful tool for studying and manipulating the differentiation of human trophoblast cells in vitro. The findings also indicate that care should be used in interpreting results obtained using DMSO as a carrier in drug and inhibitor studies. J. Cell Biochem. 65:460-468. © 1997 Wiley-Liss Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 76 (1940), S. 499-521 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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