Michail Davidoff

The guinea-pig placenta.

1. Introduction.- 2. Historical Survey.- 3. Development of the Guinea-Pig Placenta.- 3.1. Breeding and Age Determination.- 3.2. Early Development and Formal Genesis.- 3.3. Morphogenesis.- 4. Rough Structure of the Mature Placenta.- 5. Vascular Supply of the Mature Placenta.- 5.1. Maternal Arterial Blood Supply.- 5.2. Maternal Venous Drainage.- 5.3. Fetal Arterial Blood Supply.- 5.4. Fetal Venous Drainage.- 5.5. Intralobar Circulatory Conditions.- 6. Ultrastructure and Functional Morphology.- 6.1. Physiological, Technical and Morphometrical Data.- 6.1.1. Physiological Data and Perfusion Technique.- 6.1.2. Influence of Fixation on the Structure of the Placenta.- 6.1.3. Morphometry of the Main Placenta.- 6.2. Ultrastructural and Histochemical Development of the Main Placenta.- 6.2.1. 6th to 14th Day.- 6.2.2. 15th to 20th Day.- 6.2.3. 21st to 35th Day.- 6.2.4. 36th to 50th Day.- 6.3. Functional Morphology of the Different Regions in the Mature Main Placenta.- 6.3.1. Interlobium.- 6.3.2. Transitional Zone.- 6.3.3. Periphery of the Lobe.- 6.3.4. Middle of the Lobe.- 6.3.5. Centre of the Lobe.- 6.4. Subplacenta and Junctional Zone.- 6.4.1. Development and Regression of the Subplacenta.- 6.4.2. Functional Significance.- 6.5. Yolk Sac and Margin of the Placenta.- 6.5.1. Section 1 of the Yolk Sac.- 6.5.2. Section 2 of the Yolk Sac.- 6.5.3. Section 3 of the Yolk Sac.- 6.5.4. Section 4 of the Yolk Sac.- 6.5.5. Section 5 of the Yolk Sac.- 7. Possibilities of Comparison with the Human Placenta.- Acknowledgements.- 8. References.- 9. Subject Index.

Age-related morphological and morphometrical changes in parvalbumin- and calbindin-immunoreactive neurons in the rat hippocampal formation

Parvalbumin (PV)- and calbindin (CaBP)-immunostaining in the hippocampal formation of 3-, 11- and 28-month-old Wistar rats was studied using monoclonal antibodies. A quantitative analysis of the densities, cross-sectional areas, length and number of processes of PV-immunoreactive neurons in the hippocampal dentata and CA1 areas of the three age groups was employed. Marked age-related changes in the morphological appearance and in the quantitative parameters characterizing the PV-immunoreactive neurons in both hippocampal regions were observed. The intensity of CaBP-immunostaining of the hippocampal principle cells and interneurons remained the same but the immunoreactive fibers were structurally altered in aging.

SUBSTANCE P- AND NEURON-SPECIFIC ENOLASE-LIKE IMMUNOREACTIVITY OF RODENT LEYDIG CELLS IN TISSUE SECTION AND CELL CULTURE

Comparative immunocytochemical studies concerning the presence of a neurotransmitter (substance P), and a marker of neuroendocrine cells (neuron-specific enolase), in the Leydig cells of 3 mammalian species (golden hamster, guinea pig, and rat) were carried out on tissue sections and cell cultures. Substance P(SP)-like immunoreactivity (-LI) was found to be present in both fetal and adult generation of Leydig cells in hamster and guinea pig, while neuron-specific enolase (NSE)-LI was detected in Leydig cells of the 3 species at all stages studied: fetal, neonatal and adult. In primary cultures of Leydig cells isolated from adult hamster testes, SP- and NSE-LI was also established. This result was considered as an indirect evidence for the synthesis of the substances under study by the steroidogenic cells of the testis. A comparison of these results with data obtained in vivo suggests that Leydig cells may be related to the APUD- or the diffuse neuroendocrine system.

Age-related changes in serotonin-immunoreactive neurons in the rat nucleus raphe dorsalis and nucleus centralis superior : a light microscope study

Comparison of serotonin-immunoreactive (SER-IR) neurons in the nucleus raphe dorsalis (NRD) and the nucleus centralis superior (NCS) of 3-month-old and 28-month-old rats was made using qualitative and quantitative immunohistochemical analysis. Significant age-related changes in size and density of the SER-IR somata as well as in the length and number of their processes were demonstrated. A different vulnerability of the SER-IR neurons in both raphe nuclei to aging was observed that may be related to their different structural and functional features.

Reinvestigation of the transitional epithelium (urothelium) of the human ureter

The transitional epithelia (urothelia) of the ureters of 30 patients of different ages were studied by means of light and electron microscopical, histochemical and immunocytochemical methods. A great variability of the normal structural appearance of the urothelium was established. Structural features and the uptake of exogenous peroxidase by the surface epithelial cells provided high endocytotic activity. Urothelial cells take up many low and high molecular weight substances from the urine and further metabolize and transport these toward the subepithelial connective tissue. Lymphocytes, macrophages, monocytes, plasma cells and rarely polymorphonuclear leukocytes are distributed intra- and extraepithelially and are involved in the immunological response to agents which enter the intercellular spaces of the epithelium. These cells are also responsible for the elimination of aged and degenerating superficial squamous cells. The present investigation establishes the existence of immunological defence mechanisms in the adult human urothelium. The results obtained suggest that the human ureter contains three functional barriers directed against aggressive components of the urine: the first represented by structures of the superficial squamous cells, the second by the upper cells of the ureteric intermediate layer and the third comprising epithelial and immunological cells involved in immune defence mechanisms.

Localization and partial characterization of a rat ovarian granulose cell protein with a monoclonal antibody

Summry— Hybridoma cell lines were obtained from mouse splenocytes sensitized to granulosa cells collected from rat ovaries after gonadotropin stimulation. A monoclonal antibody (5G5) was obtained which reacted with granulosa cells and showed a positive reaction with serum‐free conditioned medium containing granulosa cell secreted proteins. Immoblotting of the conditioned medium and light‐ and electron‐microscopic immunocytochemistry of rat ovary show that mAb 5G5 is directed against a 59‐kDa protein which is located on the plasma membrane of granulosa cells. Furthermore, the immunoreactivity of the granulosa cells depends both on the degree of follicle development and on the position of the granulosa cells within the follicles. Strong immunoreactivity was observed in the innermost granulosa cell layers, close to the oocyte and the antral cavity. The results obtained show that mAb 5G5 is a useful marker of a 59‐kDa granulosa cell protein which might be of importance for the follicle and the occyte maturation.

Electron microscopical localization of guanylate cyclase activity in the neocortex of the guinea pig

The localization of the guanylate cyclase (GC) activity has been established in the neocortex of adult guinea pigs by means of electron microscopical histochemistry [the DMSO-method of Fujimoto et al. (1981)]. Reaction product was deposited within a population of large- and medium-sized cortical neurons as well as in the cytoplasm of a part of the dendrites of variable size and in the cytoplasm and the nuclear membrane of a number of protoplasmic astrocytes. In the perikarya of the positive neurons, the reaction precipitate was mainly located within the cisterns of the rough endoplasmic reticulum and on the nuclear membrane. In the dendrites, the reaction product was usually distributed in close contact with microtubules, microfilaments, and beneath the postsynaptic membranes of a number of axodendritic synaptic contacts. The axons and all presynaptic boutons were negative. Thus, the localization of the GC could be determined as exclusively postsynaptic. The results obtained support the view for the probable participation of cyclic GMP in the cholinergic, glutaminergic or GABAergic, or peptidergic transmitter mechanisms in the central nervous system.

Age-related changes in cholinergic and noradrenergic transmission in the rat cerebellum. A histochemical and immunocytochemical study

The histochemical and immunocytochemical distribution of some cholinergic and noradrenergic markers was compared in the cerebellum of young adult (3-month old) and aged (24-month old) Wistar rats. A decrease in the density and staining of acetyl cholinesterase (AChE) positive fibers, puncta and Golgi cells was found in both the cerebellar cortex and nuclei of aged rats. The age-related changes in choline acetyltransferase immunoreactivity were less pronounced than the changes in AChE activity. A reduction in the density of catecholamine fluorescent fibers and puncta was observed in the cerebellar cortex during aging. In aged rats the increase in monoamine oxidase (MAO)-A activity was more pronounced than the increase in MAO-B activity.

Cytochemical localization of acid phosphatase and adenosine triphosphatase in some avian mechanoreceptors

Ultrastructural distribution of acid phosphatase and adenosine triphosphatase was studied in the receptor elements of HERBST and GRANDRY sensory corpuscles. Acid phosphatase activity was established in the elements of smooth and rough endoplasmic reticulum of perineural capsule cells, as well as in the secondary lysosomes of all cell types. Particular interest was paid on the activity of myelin-like dense bodies and some clear core vesicles belonging to the axoplasm of receptor nerve fibres. Adenosine triphosphatase activity was established on the membranes of receptor structures and pinocytotic vesicles. More deposits of electron dense material were localized on the axolemma of the non-myelinated portions of the receptor nerve fibres. The functional significance and importance of the both enzymes in the receptor structures was discussed.

Ultrastructure and Functional Morphology

Description and evaluation of morphometrical and ultrastructural conditions in the guinea-pig placenta are influenced decisively by the fixation technique chosen. Studies in this field (Kaiser and Kaufmann, 1976) have revealed that perfusion fixation only provides reliable results for both ultrastructure and morphometry (cp. Fig. 13a-f). The most practicable techniques will therefore be presented briefly: Pregnant guinea-pigs are anaesthesized with 60 mg Nembutal per kg. bodyweight, injected in two por tions into the muscular system of both hind legs. To avoid reflex movements and dis turbance during preparation, local anaesthesia of the abdominal wall has proved to be useful. Moreover, we drip 1 to 2 ml of local anaesthetic into the opened abdominal ca vity. Both uterus horns are lifted out of the abdomen and laid laterally so that mesometrium and vessels are tense. To avoid desiccation of the uterus wall, it is covered by gauze soaked in Ringer’s solution.